Topic hub — 2026-10-22
Does the way olive oil is extracted or stored change its bitterness?
To be clear from the start, this page is about bitterness tasted on the tongue, read separately from the peppery throat irritation (pungency) and from the fruity aroma (fruitiness). The bitterness of extra virgin olive oil is commonly attributed not only to cultivar and ripeness but also to the steps of extraction and to filtration and storage after milling. So what do studies say that changed only the process or storage for the same fruit or oil and had people rate bitterness? This page collects comparisons that changed the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container). Which compounds set the bitterness is covered on the page Which compounds set the bitterness of extra virgin olive oil?, and explanations based on compound levels are left to that page. In the included studies the direction differed by process and, even within one process, split by study or cultivar: there are rises, falls and comparisons with no significant difference. Many studies show values only in figures or give no sensory test result, so please check the test in each row. Fruit, scales, raters and aggregation differ by study, so it cannot be said across studies after how many months or by how many points. This page lines up the included studies together with their conditions: the fruit and oil, what was changed, and who rated them on what scale. It then separates what was established within one experiment, what differences might explain, and what this comparison alone cannot separate. It is about perceived taste, not advice on choosing, buying or storing olive oil.
On this page (10 sections)
- What this page establishes
- What the included studies allow us to say
- Bitterness ratings at a glance
- Conditions and results, study by study
- What was established within an experiment
- Candidate explanations for the differences
- What is not known — what this comparison alone cannot separate
- How studies and rows were counted
- What we looked at
- Read in the encyclopedia
What this page establishes
- That with a pulsed electric field the bitterness score rose in some industrial and pilot trials while it fell in the industrial trial of one of those studies, and none of these comes with a sensory test result.
- That the authors write that adding oxygen at crushing tended to lower bitterness and that destoning tended to raise it (values are in figures we did not check).
- That the difference between press and three-phase decanter split by cultivar, with only some cultivars differing significantly.
- That filtration significantly lowered bitterness in one cultivar while in another study the filtered oil was more bitter, so the direction is not one way; and that oil left to settle under nitrogen with racking fell.
- That comparisons holding the fruit before milling, putting it in a hopper or freezing it showed a mix of downward tendencies, differences by date and no significant difference.
- That in oil storage there were falls, rises and no significant change, and scales and aggregation differ by study, so values cannot be compared across studies.
- That several studies come from the same assessment body or research group and are not counted as independent replications, and that no significant difference does not mean the same.
What the included studies allow us to say
- In comparisons of extraction methods, the direction depended on the process. With a pulsed electric field, bitterness scores rose from 3.2 to 3.9 at a Picholine mill (Leone et al. 2022) and from 3.3 to 4.5 in pilot trial 2 with Manzanilla (Navarro et al. 2022), but fell from 4.85 to 4.10 in the industrial trial of the same study. None of these values comes with a sensory test result. The authors write that bitterness tended to fall when oxygen was added at crushing in Coratina (Veneziani et al. 2023), and that destoned Peranzana and Coratina were more bitter (Nucciarelli et al. 2024), as tendencies across processes (values for individual pairs are in figures and unconfirmed). [rows: Leone 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Picholine, industrial); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, pilot); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, industrial); Veneziani 2023 Malaxation and extraction: no oxygen vs added oxygen at crushing (Coratina) [direction from text; significance across processes]; Nucciarelli 2024 Malaxation and extraction: normal crushing vs destoning (Peranzana, both without oxygen) [direction of this pair unconfirmed]; Nucciarelli 2024 Malaxation and extraction: normal crushing vs destoning (Coratina, both without oxygen) [direction of this pair unconfirmed]]
- Filtration, too, split by cultivar and time point. In Istarska bjelica (Brkić Bubola et al. 2019) filtration was reported to lower bitterness significantly, while in Frantoio (Guerrini et al. 2020) the filtered oil was more bitter after 15 days (3 and 5). In Picual (Díez-Betriu et al. 2023) the unfiltered oil scored 4.4 and the filtered oil 4.9, with no test result shown. Coratina left to settle under nitrogen with monthly racking (Ciafardini et al. 2022) fell significantly from 4.8 at 0 days to 3.2 at 90 days. Studies that held fruit for 7 days before milling, put it in a hopper, or froze it showed a mix of downward tendencies, differences by date, and no significant difference. [rows: Brkić Bubola 2019 Filtration and racking: unfiltered vs filtered (Istarska bjelica, fresh) [significance from text; filtered value unconfirmed]; Guerrini 2020 Filtration and racking: unfiltered vs filtered (Frantoio, after 15 days, no high pressure) [significance of this pair unconfirmed]; Díez-Betriu 2023 Filtration and racking: unfiltered vs filtered (Picual, start of storage); Ciafardini 2022 Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking); Brkić Bubola 2020 Fruit storage and handling: immediately after harvest vs fruit kept 7 days (Rosinjola) [direction from text]; Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (December, ripe) [direction differs by position]; Antonelli 2024 Fruit storage and handling: fresh fruit vs frozen fruit (Arbequina)]
- Storage comparisons did not point one way either. Bitterness fell from 15 days to 6 months in one study (Guerrini et al. 2020, filtered oil from 5 to 2) and a significant fall was reported over a 40-day storage test with daily opening and withdrawal in another (Sordini et al. 2026; the individual 0 vs 40 day comparison unconfirmed), while it rose from immediately after production to 12 months in a third (Breschi et al. 2025, 2 oils from 3.9 to 6.0 and 6.3 and from 2.9 to 4.3 and 6.1, no test described), and a fourth reports no significant change 125 days after packaging (Sanmartin et al. 2018, values not published). Scales and aggregation differ by study, so it cannot be said across studies after how many months or by how many points. [rows: Guerrini 2020 Oil storage: 15 days vs 6 months (Frantoio, filtered oil) [significance is the time main effect]; Sordini 2026 Oil storage: change over storage, 0–40 days (Moraiolo, opened and drawn daily; PET, bag-in-box, tin) [direction from text; significance of 0 vs 40 days unconfirmed]; Breschi 2025 Oil storage: immediately after production vs 12 months (oil B, 250 mL bottle); Breschi 2025 Oil storage: immediately after production vs 12 months (oil B, 500 mL bottle); Breschi 2025 Oil storage: immediately after production vs 12 months (oil P, 250 mL bottle); Breschi 2025 Oil storage: immediately after production vs 12 months (oil P, 500 mL bottle); Sanmartin 2018 Oil storage: at packaging vs after 125 days (greenish glass and tin, 6 °C and 26 °C)]
Bitterness ratings at a glance
Human bitterness ratings only. Fruit, scales and aggregation differ by study, so values are not compared across studies. The two conditions compared are set out as the condition before and the condition after "vs" in the label. Before "vs" we put the side without the new treatment, before treatment, at the start of storage, or not passed through the hopper. The "Direction" column shows which condition was more bitter ("... more bitter"). The direction shows which published value is larger or, when values are only in figures, what the text states, and is not necessarily the result of an individual test between the two conditions shown. Whether the difference is significant is shown by the test in the same "Direction / test" column; even in rows with no significant difference, the direction shows which value is larger. Rows with no test result shown are not described as not significant. Rows whose values are only in figures we did not obtain, and rows whose values were not published, are kept as they are. A tag at the start of each label shows the kind of process: "Malaxation and extraction" for crushing, oxygen, destoning, extraction system and outlet; "Pulsed electric fields and ultrasound" for new treatments added before, after or instead of malaxation; "Filtration and racking" for clarification after milling; "Fruit storage and handling" for how the fruit was kept before milling; and "Oil storage" for time, temperature and container after milling. Where a new treatment changed together with malaxation time or flow, the label or the conditions say so. Where the direction comes from the text, where the test concerns all processes or a main effect, or where the same value is included, a short note in [ ] at the end of the label says so. Where the unit column says the source gives a value ± SD, only the central value (mean or median) is shown. Select a study name to jump to its detailed table.
Results in which people rated bitterness only. Where each value comes from (a table or a reading from a figure) is shown in its row; scales and methods differ between studies, so compare within a row, not across rows.
| Study | Comparison and condition | Measured as | Condition before "vs" | Condition after "vs" | Direction / test |
|---|---|---|---|---|---|
| Peralta 2024 | Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (15 min malaxation trial) 1 industrial trial with early-harvest Royal fruit (malaxation 15 min at 32.6 °C); oil from the same batch sampled at the decanter outlet and at the subsequent vertical centrifuge outlet | the source gives median ± asymptotic robust SD; the median is shown here (8 expert assessors in Granada; scale range not stated in the text) | 2.7 | 2.6 | Condition before "vs" more bitter Tested, not significant |
| Peralta 2024 | Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (30 min malaxation trial) 1 industrial trial with early-harvest Royal fruit (malaxation 30 min at 31.6 °C); oil from the same batch sampled at the decanter outlet and at the subsequent vertical centrifuge outlet | the source gives median ± asymptotic robust SD; the median is shown here (8 expert assessors in Granada; scale range not stated in the text) | 3.4 | 3.2 | Condition before "vs" more bitter Tested, not significant |
| Veneziani 2023 | Malaxation and extraction: no oxygen vs added oxygen at crushing (Coratina) [direction from text; significance across processes] Coratina fruit milled in the same pilot plant with oxygen supplied to the crusher at 0, 0.2, 0.4 and 0.8 L/min | QDA line scale (9 expert panellists; the description of the scale structure is inconsistent and its range unclear) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Veneziani 2023 | Malaxation and extraction: no oxygen vs added oxygen at crushing (Ogliarola) Ogliarola fruit milled in the same pilot plant with oxygen supplied to the crusher at 0, 0.2, 0.4 and 0.8 L/min | QDA line scale (9 expert panellists; the description of the scale structure is inconsistent and its range unclear) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Test method described; result for this comparison not reported |
| Nucciarelli 2024 | Malaxation and extraction: normal crushing vs destoning (Peranzana, both without oxygen) [direction of this pair unconfirmed] Peranzana fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | unstructured QDA scale (trained panel; size and range not stated in the text) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Tested; significance reported, but which pair differs is unclear |
| Nucciarelli 2024 | Malaxation and extraction: no oxygen vs oxygen 0.2 L/min (Peranzana, both with normal crushing) [direction of this pair unconfirmed] Peranzana fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | unstructured QDA scale (trained panel; size and range not stated in the text) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Tested; significance reported, but which pair differs is unclear |
| Nucciarelli 2024 | Malaxation and extraction: normal crushing vs destoning (Coratina, both without oxygen) [direction of this pair unconfirmed] Coratina fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | unstructured QDA scale (trained panel; size and range not stated in the text) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Tested; significance reported, but which pair differs is unclear |
| Nucciarelli 2024 | Malaxation and extraction: no oxygen vs oxygen 0.2 L/min (Coratina, both with normal crushing) [direction of this pair unconfirmed] Coratina fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | unstructured QDA scale (trained panel; size and range not stated in the text) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Tested; significance reported, but which pair differs is unclear |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Arbequina) Arbequina: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 1.70 | 1.50 | Condition before "vs" more bitter Tested, not significant |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Chemchali) Chemchali: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 3.56 | 2.53 | Condition before "vs" more bitter Tested, not significant |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Chemlali) Chemlali: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 1.00 | 1.80 | Condition after "vs" more bitter Tested, not significant |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Chetoui) Chetoui: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 0.00 | 3.83 | Condition after "vs" more bitter Tested, significant |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Coratina) Coratina: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 3.50 | 4.40 | Condition after "vs" more bitter Tested, not significant |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Leguim) Leguim: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 0.00 | 2.43 | Condition after "vs" more bitter Tested, significant |
| Ben-Hassine 2022 | Malaxation and extraction: press vs three-phase decanter (Zalmati) Zalmati: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | 2.30 | 1.80 | Condition before "vs" more bitter Tested, not significant |
| Leone 2022 | Pulsed electric fields and ultrasound: without vs with pulsed electric field (Picholine, industrial) Homogeneous Picholine lots (ripeness index 2.9) processed alternately with the pulsed electric field (2.4 kV/cm, 4 kJ/kg) on or off, 5 trials per condition; malaxation 30 min at 26 °C in both | median (IOC method; panel size and scale range not given) | 3.2 | 3.9 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Navarro 2022 | Pulsed electric fields and ultrasound: no pulsed electric field with 90 min malaxation vs pulsed electric field with 45 min malaxation (Manzanilla, pilot) Pilot trial 1; Manzanilla (turning stage), pulsed electric field 2 kV/cm and 5 kJ/kg; malaxation time also differs, 90 vs 45 min; decanter flow 384 kg/h in both | IOC-method score (accredited Instituto de la Grasa panel; panel size, scale range and median or mean not given) | 3.8 | 4.4 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Navarro 2022 | Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, pilot) Pilot trial 2; Manzanilla, pulsed electric field 2 kV/cm and 5 kJ/kg; malaxation 30 min and decanter flow 310 kg/h in both | IOC-method score (accredited Instituto de la Grasa panel; panel size, scale range and median or mean not given) | 3.3 | 4.5 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Navarro 2022 | Pulsed electric fields and ultrasound: without vs with pulsed electric field (Hojiblanca, pilot; flow also differs) Pilot trial 3; Hojiblanca, pulsed electric field 2 kV/cm and 5 kJ/kg, malaxation 30 min in both; decanter flow differs, 318 vs 384 kg/h, and temperature before the pulsed electric field, 21.2 vs 18.3 °C | IOC-method score (accredited Instituto de la Grasa panel; panel size, scale range and median or mean not given) | 2.6 | 3.1 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Navarro 2022 | Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, industrial) Industrial trial (2021, a line with a capacity of 4000 kg/h; decanter flow 2400 kg/h in both during the trial); Manzanilla, pulsed electric field 2 kV/cm and 5 kJ/kg, malaxation 30 min in both | IOC-method score (accredited Instituto de la Grasa panel; panel size, scale range and median or mean not given) | 4.85 | 4.10 | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Boffa 2024 | Pulsed electric fields and ultrasound: conventional 30 min malaxation vs ultrasound instead of malaxation (Coratina, industrial) [authors state significance; test details not reported] Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; conventional malaxation 30 min at 30 °C, ultrasound (25 kHz) replaced malaxation | median (external trained panel; panel size and scale range not given) | 3.5 | 3.9 | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Boffa 2024 | Pulsed electric fields and ultrasound: conventional 30 min malaxation vs malaxation followed by pulsed electric field (positive) (Coratina, industrial) [authors state significance; test details not reported] Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; both with malaxation 30 min at 30 °C, one followed by a pulsed electric field (positive) | median (external trained panel; panel size and scale range not given) | 3.5 | 3.9 | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Boffa 2024 | Pulsed electric fields and ultrasound: ultrasound alone vs ultrasound plus pulsed electric field (positive) (Coratina, industrial) Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; both with ultrasound (25 kHz) instead of malaxation | median (external trained panel; panel size and scale range not given) | 3.9 | 3.8 | Condition before "vs" more bitter No test reported |
| Boffa 2024 | Pulsed electric fields and ultrasound: ultrasound alone vs ultrasound plus pulsed electric field (bipolar) (Coratina, industrial) Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; both with ultrasound (25 kHz) instead of malaxation | median (external trained panel; panel size and scale range not given) | 3.9 | 4.0 | Condition after "vs" more bitter No test reported |
| Cecchi 2019 | Pulsed electric fields and ultrasound: conventional (30 min malaxation) vs sono-heat-exchanger (0 min malaxation) [direction from text; sensory figure of 2 samples] Homogeneous fruit lots divided into 800 kg portions, processed alternately with the sono-heat-exchanger and 0 min malaxation or without it and 30 min malaxation (the text gives the temperature as both 24 °C and 25 °C) | IOC method (11 tasters of the University of Bari; scale range and mean or median not stated) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Manganiello 2021 | Pulsed electric fields and ultrasound: without vs with ultrasound (Peranzana, Canino, Coratina) [direction from text; significance across processes] About 200 kg of fruit per process trial, milled by normal crushing with or without ultrasound (3 replicates each per cultivar; malaxation at 25 °C, two-phase decanter) | 0.0–10.0 scale (CREA Pescara panel, size not given; mean of 3 replicates) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Manganiello 2021 | Pulsed electric fields and ultrasound: normal crushing vs destoning plus ultrasound (Coratina) [direction from text; significance across processes] Coratina fruit, about 200 kg per process trial, milled by normal crushing, or destoned and then ultrasonicated (3 replicates each; malaxation at 25 °C, two-phase decanter) | 0.0–10.0 scale (CREA Pescara panel, size not given; mean of 3 replicates) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Brkić Bubola 2019 | Filtration and racking: unfiltered vs filtered (Istarska bjelica, fresh) [significance from text; filtered value unconfirmed] Istarska bjelica; The same freshly produced oil filtered through a cellulose filter press or left unfiltered (3 times each) | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | 5.2 | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Tested, significant |
| Brkić Bubola 2019 | Filtration and racking: unfiltered vs filtered (Buža, fresh) Buža; The same freshly produced oil filtered through a cellulose filter press or left unfiltered (3 times each) | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | 2.5 | Figure not obtained, so values unconfirmed | Direction not given Test method described; result for this comparison not reported |
| Brkić Bubola 2019 | Filtration and racking: filtered vs natural sedimentation and decanting (Istarska bjelica, after 6 months) [direction from text] Istarska bjelica; Filtered oil and oil left to settle naturally for 45 days at 16 °C and decanted from the sediment, compared after 6 months of storage at 16 °C | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Brkić Bubola 2019 | Filtration and racking: filtered vs natural sedimentation and decanting (Buža, after 6 months) Buža; Filtered oil and oil left to settle naturally for 45 days at 16 °C and decanted from the sediment, compared after 6 months of storage at 16 °C | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Test method described; result for this comparison not reported |
| Guerrini 2020 | Filtration and racking: unfiltered vs filtered (Frantoio, after 15 days, no high pressure) [significance of this pair unconfirmed] Oil from the decanter split immediately in half, one half filtered through a filter press; both without high-pressure treatment, 15 days in transparent PET at 20 °C and 1900 lux | the source gives mean ± SD of 4 trials; the mean (integer) is shown here (8 trained panellists, IOC method, scale range not stated) | 3 | 5 | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Díez-Betriu 2023 | Filtration and racking: unfiltered vs filtered (Picual, start of storage) Produced on the same day from the same fruit batch, one filtered by the producer through cellulose; sampled 7 days after production; moisture and volatile matter 0.376% unfiltered, 0.036% filtered | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | 4.4 | 4.9 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Ciafardini 2022 | Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking) The same freshly produced Coratina oil held under nitrogen in 3 stainless steel tanks of 200 L and sampled at 0, 30, 60 and 90 days; sludge drained and headspace replaced with nitrogen at each sampling | median on a 0 (absent) to 5 (highest) scale (recognised panel, size not given) | 4.8 | 3.2 | Condition before "vs" more bitter Tested, significant |
| Brkić Bubola 2020 | Fruit storage and handling: immediately after harvest vs fruit kept 7 days (Istarska bjelica) [direction from text] Istarska bjelica fruit milled immediately after harvest or after 7 days at room temperature (22 ± 4 °C), +4 °C or −20 °C (batches of 3 kg) | mean of the medians of 3 technical replicates (8 trained assessors; scale range not stated in the text) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Depends on the combination Test method described; result for this comparison not reported |
| Brkić Bubola 2020 | Fruit storage and handling: immediately after harvest vs fruit kept 7 days (Rosinjola) [direction from text] Rosinjola fruit milled immediately after harvest or after 7 days at room temperature (22 ± 4 °C), +4 °C or −20 °C (batches of 3 kg) | mean of the medians of 3 technical replicates (8 trained assessors; scale range not stated in the text) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Boudebouz 2023 | Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (November, green) [2 pairs higher before vs; T20 the same value] About 22,000 kg of Arbequina harvested and delivered on the same day and held in a large hopper for about 3 hours; fruit taken 1, 10 and 20 minutes after unloading began (T1, T10, T20) and fruit kept in small boxes without the hopper (Ref) milled at laboratory scale (malaxation 30 min at 24 °C); November experiment (the methods say the 26th, the results the 27th) | 10 cm scale (8 tasters of the Official Tasting Panel of Catalonia; the methods give medians and the table footnote means, inconsistent) | 3.6 | 2.7 (T1), 3.4 (T10), 3.6 (T20) | Depends on the combination Tested, only some pairs significant |
| Boudebouz 2023 | Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (December, ripe) [direction differs by position] About 22,000 kg of Arbequina harvested and delivered on the same day and held in a large hopper for about 3 hours; fruit taken 1, 10 and 20 minutes after unloading began (T1, T10, T20) and fruit kept in small boxes without the hopper (Ref) milled at laboratory scale (malaxation 30 min at 24 °C); experiment of 12 December | 10 cm scale (8 tasters of the Official Tasting Panel of Catalonia; the methods give medians and the table footnote means, inconsistent) | 4.2 | 4.2 (T1), 4.3 (T10), 2.1 (T20) | Depends on the combination Tested, only some pairs significant |
| Boudebouz 2023 | Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (January, overripe) About 22,000 kg of Arbequina harvested and delivered on the same day and held in a large hopper for about 3 hours; fruit taken 1, 10 and 20 minutes after unloading began (T1, T10, T20) and fruit kept in small boxes without the hopper (Ref) milled at laboratory scale (malaxation 30 min at 24 °C); experiment of 7 January (overripe, frost-damaged fruit) | 10 cm scale (8 tasters of the Official Tasting Panel of Catalonia; the methods give medians and the table footnote means, inconsistent) | 2.1 | 3.2 (T1), 2.7 (T10), 2.6 (T20) | Condition after "vs" more bitter Tested, only some pairs significant |
| Antonelli 2024 | Fruit storage and handling: fresh fruit vs frozen fruit (Arbequina) Chilean Arbequina; for 15 cultivation treatments × 3 harvest months, fruit from each tree split in 2, one portion kept at −3 ± 1 °C for 12 hours, thawed at room temperature for 2–4 hours and then milled | IOC-method score (9 trained tasters; the methods give the mean of tasters and the results the average of panel medians, inconsistent) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Tested, not significant |
| Guerrini 2020 | Oil storage: 15 days vs 6 months (Frantoio, filtered oil) [significance is the time main effect] Filtered Frantoio oil; Transparent 250 mL PET bottles at 20 °C under 1900 lux for 8 h a day; no high-pressure treatment; rated at 15 days, 1 month and 6 months | the source gives mean ± SD of 4 trials; the mean (integer) is shown here (8 trained panellists, IOC method, scale range not stated) | 5 | 2 | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Guerrini 2020 | Oil storage: 15 days vs 6 months (Frantoio, unfiltered oil) [significance is the time main effect] Unfiltered Frantoio oil; Transparent 250 mL PET bottles at 20 °C under 1900 lux for 8 h a day; no high-pressure treatment; rated at 15 days, 1 month and 6 months | the source gives mean ± SD of 4 trials; the mean (integer) is shown here (8 trained panellists, IOC method, scale range not stated) | 3 | 1 | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Díez-Betriu 2023 | Oil storage: start vs 6 months at room temperature (Picual, unfiltered oil) Unfiltered Picual oil; glass bottles in the dark at room temperature for 6 months (the non-frozen control in Table 2) | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | 4.4 | 3.6 | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Díez-Betriu 2023 | Oil storage: start vs 6 months at room temperature (Picual, filtered oil) Filtered Picual oil; glass bottles in the dark at room temperature for 6 months (the non-frozen control in Table 2) | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | 4.9 | 5.2 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Díez-Betriu 2023 | Oil storage: −20 °C vs room temperature or 4 °C for 24 months (Picual, unfiltered oil) [direction from text; significance is the interaction] Unfiltered Picual oil kept in the dark at −20 °C (slow and fast freezing) or at room temperature or 4 °C for 24 months | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Abuhabib 2025 | Oil storage: 0 vs 12 months (Corbella, bag-in-box) Corbella oil (fruit harvested on 2 dates in October 2022; filtered) stored at 22–23 °C; bag-in-box | the source gives mean of medians ± SD (Table 3 footnote); the mean is shown here (the methods say the mean of 8 tasters, inconsistent; Official Tasting Panel of Catalonia, 10 cm) | 4.60 | 4.72 | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Abuhabib 2025 | Oil storage: 0 vs 12 months (Corbella, stainless steel with nitrogen) Corbella oil (fruit harvested on 2 dates in October 2022; filtered) stored at 22–23 °C; stainless steel container with a nitrogen headspace | the source gives mean of medians ± SD (Table 3 footnote); the mean is shown here (the methods say the mean of 8 tasters, inconsistent; Official Tasting Panel of Catalonia, 10 cm) | 4.60 | 4.32 | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Abuhabib 2025 | Oil storage: bag-in-box vs stainless steel with nitrogen (Corbella, 12 months) Corbella oil (fruit harvested on 2 dates in October 2022; filtered) stored at 22–23 °C; containers compared at 12 months | the source gives mean of medians ± SD (Table 3 footnote); the mean is shown here (the methods say the mean of 8 tasters, inconsistent; Official Tasting Panel of Catalonia, 10 cm) | 4.72 | 4.32 | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Breschi 2025 | Oil storage: immediately after production vs 12 months (oil B, 250 mL bottle) Oil B in 250 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | 3.9 | 6.0 | Condition after "vs" more bitter No test reported |
| Breschi 2025 | Oil storage: immediately after production vs 12 months (oil B, 500 mL bottle) Oil B in 500 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | 3.9 | 6.3 | Condition after "vs" more bitter No test reported |
| Breschi 2025 | Oil storage: immediately after production vs 12 months (oil P, 250 mL bottle) Oil P in 250 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | 2.9 | 4.3 | Condition after "vs" more bitter No test reported |
| Breschi 2025 | Oil storage: immediately after production vs 12 months (oil P, 500 mL bottle) Oil P in 500 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | 2.9 | 6.1 | Condition after "vs" more bitter No test reported |
| Sanmartin 2018 | Oil storage: at packaging vs after 125 days (greenish glass and tin, 6 °C and 26 °C) The same oil, kept 63 days in silos under nitrogen, packed in greenish glass bottles (100 mL) and tins (175 mL) and stored at 6 °C and 26 °C for 125 days | QDA, 0–10, means (10 trained assessors of the University of Pisa) | Values not published (data not shown) | Values not published (data not shown) | Direction not given Tested, not significant |
| Sordini 2026 | Oil storage: change over storage, 0–40 days (Moraiolo, opened and drawn daily; PET, bag-in-box, tin) [direction from text; significance of 0 vs 40 days unconfirmed] The same Moraiolo oil filled into 3 L PET, bag-in-box and tin containers at 25 °C under 500 lux for 12 h a day; opened daily with 75 mL withdrawn; sensory ratings used a composite sample of about 160 mL pooling chemical-analysis residues, the sensory sample and the previous sampling day, not oil taken on day 40 alone | 9 cm line scale from 0 to 9, mean of 10 panellists (10 experienced judges of the University of Perugia) | 4.31 | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| De Santis 2024 | Oil storage: −20 °C vs room temperature for 12 months (Biancolilla and Cerasuola) [direction from text] Filtered and unfiltered Biancolilla and Cerasuola oils in nitrogen-saturated green glass bottles kept in the dark at −20 ± 3 °C or 20 ± 2 °C for 12 months (the abstract says 18 °C) | 10 cm scale (8 trained judges; mean or median not stated) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Tucci 2025 | Oil storage: 0 vs 12 months (Nostrana di Brisighella) [direction from text] Nostrana di Brisighella oils from one area (2 cultivation systems × 4 harvest weeks) kept in a room with natural light at about 25 °C for 0, 6 and 12 months | median on a 10 cm scale (official DISTAL panel of the University of Bologna, size not given) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Condition before "vs" more bitter No test reported |
| Mousavi 2021 | Oil storage: −18 °C vs 4 °C for 18 months (3 oils with different phenol levels) [the text summarises all periods; direction at this point unconfirmed] 3 oils with low, medium and high phenols kept in 250 mL amber glass bottles in the dark at −18 °C or 4 °C for 18 months | 0–10; Fig. 6 gives the median of 15 evaluations (3 replicates × 5 tasters) (Slow Food panel, 5 tasters and a leader; modified IOC method) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | Direction not given Test method described; result for this comparison not reported |
Conditions and results, study by study
For each study, the conditions for the fruit and oil, the extraction, the treatment or storage, how samples were served and who rated them, and the results. Each row is one study × one measured result, so different comparisons in the same study are separate rows. Under each row we give where it is in the paper and whether it can be used to judge whether changing the extraction, filtration or racking, the handling of the fruit before milling, or the storage of the oil, for the same fruit or the same oil, changes the intensity of bitterness people perceive, with the reason. Where other conditions changed together, the reason says the row is usable only as a comparison of combined processes. Authors' explanations in terms of phenol levels or breakdown mechanisms are only touched on as candidates, and the correspondence between compounds and bitterness is left to the olive oil bitterness page. Nothing is left blank: "not given", "not read" and "not applicable" are kept apart, and values from figures we did not obtain are marked as such. Where a study's methods and tables disagree on whether medians or means were used, the disagreement is kept.
Peralta 2024 sensory only
Olive Oil (Royal Cultivar) from Mill Obtained by Short Time Malaxation and Early Ripening Stage. Foods 13(16):2588 — doi:10.3390/foods13162588
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 3.3, 3.5; Tables 4 and 6) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-21.
- Samples
- Early-harvest Royal oil (ripeness index about 1.05) from a Spanish mill; 1 industrial run per condition
- Processing and cooking
- 2 industrial runs with 15 and 30 minutes of malaxation (on different days and batches, also differing in temperature and fruit oil content)
- How it was served or eaten
- Not applicable (oils assessed as produced)
- Who rated, on what scale
- 8 experts at an accredited laboratory, rating bitterness, pungency and fruitiness separately; compounds by HPLC in the same oils
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (15 min malaxation trial) 1 industrial trial with early-harvest Royal fruit (malaxation 15 min at 32.6 °C); oil from the same batch sampled at the decanter outlet and at the subsequent vertical centrifuge outlet | 2.7 | 2.6 | the source gives median ± asymptotic robust SD; the median is shown here (8 expert assessors in Granada; scale range not stated in the text) | Condition before "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 6, 2.7 (ab) and 2.6 (a) share a letter: not significant (which does not mean the same). A different comparison (outlet) from the malaxation-time comparison (pr-malax) on the existing olive oil bitterness page. The letters in Table 6 compare 4 groups (2 outlets × 2 malaxation trials) at once by Fisher LSD (0.54), overall p=0.0243. The 15 vs 30 min malaxation comparison was on different days and batches, with temperature and fruit oil content also differing, so it is not a row here (it is covered on the existing olive oil bitterness page) Where: Sections 2.1, 2.6, 2.7 and 3.5; Tables 1 and 6 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Oil from the same batch sampled at 2 outlets, rated by the same panel, with a test; one industrial run | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (30 min malaxation trial) 1 industrial trial with early-harvest Royal fruit (malaxation 30 min at 31.6 °C); oil from the same batch sampled at the decanter outlet and at the subsequent vertical centrifuge outlet | 3.4 | 3.2 | the source gives median ± asymptotic robust SD; the median is shown here (8 expert assessors in Granada; scale range not stated in the text) | Condition before "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 6, 3.4 (c) and 3.2 (bc) share a letter: not significant (which does not mean the same). A different comparison (outlet) from the malaxation-time comparison (pr-malax) on the existing olive oil bitterness page. The letters in Table 6 compare 4 groups (2 outlets × 2 malaxation trials) at once by Fisher LSD (0.54), overall p=0.0243. The 15 vs 30 min malaxation comparison was on different days and batches, with temperature and fruit oil content also differing, so it is not a row here (it is covered on the existing olive oil bitterness page) Where: Sections 2.1, 2.6, 2.7 and 3.5; Tables 1 and 6 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Oil from the same batch sampled at 2 outlets, rated by the same panel, with a test; one industrial run | |||||
Leone 2022 sensory only
Investigation on the Effects of a Pulsed Electric Field (PEF) Continuous System Implemented in an Industrial Olive Oil Plant. Foods 11(18):2758 — doi:10.3390/foods11182758
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1–2.4, 2.8.4, 2.9, 3.3 and 3.5; Table 6) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Picholine fruit (ripeness index 2.9) at an industrial mill in Apulia (capacity 1500 kg/h)
- Processing and cooking
- Homogeneous fruit lots processed alternately with the pulsed electric field between crusher and malaxer switched on or off (2.4 kV/cm, 4 kJ/kg), 5 trials per condition; malaxation 30 min at 26 °C in both, three-phase decanter
- How it was served or eaten
- Not given (stated only as following the IOC method)
- Who rated, on what scale
- IOC method; panel size and scale range not given; Table 6 gives medians; the statistics section mentions t tests, but no test result for the sensory values is given
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: without vs with pulsed electric field (Picholine, industrial) Homogeneous Picholine lots (ripeness index 2.9) processed alternately with the pulsed electric field (2.4 kV/cm, 4 kJ/kg) on or off, 5 trials per condition; malaxation 30 min at 26 °C in both | 3.2 | 3.9 | median (IOC method; panel size and scale range not given) | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. The medians in Table 6 carry no significance marks. The statistics section mentions t tests, but no test result for the sensory values is given. The text says the pulsed electric field raised the bitterness score Where: Sections 2.1, 2.4, 2.8.4, 2.9 and 3.5; Table 6 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Homogeneous lots processed alternately with only the pulsed electric field changed (same malaxation); however, there is no sensory test result and panel size is not given | |||||
Boffa 2024 sensory only
Industrial Production of Bioactive Nutrient-Enhanced Extra Virgin Olive Oil under Continuous-Flow Ultrasound and Pulsed Electric Field Treatment. Foods 13(16):2613 — doi:10.3390/foods13162613
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.3–2.4 and 3.1–3.2; Table 2; the Fig. 1 legend); the storage sensory data (Fig. 6) and supplementary tables were not read Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Green Coratina from the same batch on the same day (1800 kg per condition)
- Processing and cooking
- Conventional (malaxation 30 min at 30 °C), ultrasound (25 kHz) instead of malaxation, ultrasound plus pulsed electric field (positive or bipolar), and malaxation plus pulsed electric field (positive); all with a three-phase decanter and 250 L/h of added water
- How it was served or eaten
- Not given
- Who rated, on what scale
- A selected, trained external panel; panel size and scale range not given; Table 2 gives medians; the statistics section covers ANOVA with Tukey for tocopherols and phenols only, with no sensory test described
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: conventional 30 min malaxation vs ultrasound instead of malaxation (Coratina, industrial) [authors state significance; test details not reported] Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; conventional malaxation 30 min at 30 °C, ultrasound (25 kHz) replaced malaxation | 3.5 | 3.9 | median (external trained panel; panel size and scale range not given) | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction shows which published value is larger. Ultrasound replaced malaxation, so its effect cannot be separated from that of dropping malaxation. The authors state that the bitterness medians of the new processes (3.8–4.0) were significantly higher than conventional (3.5), but the sensory test method and individual statistics are not reported (the statistics section covers compounds only) Where: Sections 2.3, 2.4 and 3.2; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same batch, but ultrasound replaced malaxation, so its effect and that of dropping malaxation change together; the authors state significance, but the sensory test method is not reported | |||||
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: conventional 30 min malaxation vs malaxation followed by pulsed electric field (positive) (Coratina, industrial) [authors state significance; test details not reported] Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; both with malaxation 30 min at 30 °C, one followed by a pulsed electric field (positive) | 3.5 | 3.9 | median (external trained panel; panel size and scale range not given) | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction shows which published value is larger. The authors state that the bitterness medians of the new processes (3.8–4.0) were significantly higher than conventional (3.5), but the sensory test method and individual statistics are not reported (the statistics section covers compounds only) Where: Sections 2.3, 2.4 and 3.2; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Same batch with malaxation matched and only the pulsed electric field changed; the authors state it was significantly higher, but the sensory test method and individual statistics are not reported | |||||
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: ultrasound alone vs ultrasound plus pulsed electric field (positive) (Coratina, industrial) Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; both with ultrasound (25 kHz) instead of malaxation | 3.9 | 3.8 | median (external trained panel; panel size and scale range not given) | Condition before "vs" more bitter No test reported |
| Direction shows which published value is larger. No test of adding a pulsed electric field to ultrasound is reported Where: Sections 2.3, 2.4 and 3.2; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Same batch, both with ultrasound instead of malaxation and only the pulsed electric field changed; however, there is no sensory test | |||||
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: ultrasound alone vs ultrasound plus pulsed electric field (bipolar) (Coratina, industrial) Green Coratina from the same batch on the same day (1800 kg per condition) processed at industrial scale; three-phase decanter with 250 L/h of water; both with ultrasound (25 kHz) instead of malaxation | 3.9 | 4.0 | median (external trained panel; panel size and scale range not given) | Condition after "vs" more bitter No test reported |
| Direction shows which published value is larger. No test of adding a pulsed electric field to ultrasound is reported Where: Sections 2.3, 2.4 and 3.2; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Same batch, both with ultrasound instead of malaxation and only the pulsed electric field changed; however, there is no sensory test | |||||
Veneziani 2023 sensory only
Effect of Controlled Oxygen Supply during Crushing on Volatile and Phenol Compounds and Sensory Characteristics in Coratina and Ogliarola Virgin Olive Oils. Foods 12(3):612 — doi:10.3390/foods12030612
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1, 2.5, 2.6 and 3.4; the legends of Figs 1–4); figures not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Coratina and Ogliarola fruit; University of Perugia pilot plant
- Processing and cooking
- Oxygen supplied to the crusher at 0 (control), 0.2, 0.4 and 0.8 L/min (fruit flow about 640 kg/h)
- How it was served or eaten
- White plastic cups coded with 3-digit numbers
- Who rated, on what scale
- 9 expert panellists from the University of Perugia, QDA; the methods describe a structured geometric scale and the results an unstructured scale, inconsistent; scale range unclear; one-way ANOVA with Tukey
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Malaxation and extraction: no oxygen vs added oxygen at crushing (Coratina) [direction from text; significance across processes] Coratina fruit milled in the same pilot plant with oxygen supplied to the crusher at 0, 0.2, 0.4 and 0.8 L/min | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | QDA line scale (9 expert panellists; the description of the scale structure is inconsistent and its range unclear) | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction from the text (bitterness and pungency tend to fall as the oxygen supply increases). The text reports a significant difference between processes for Coratina bitterness (p<0.05), but which pairs differ is in a figure and unconfirmed. The text says the bitterness median exceeded 4 in all samples Where: Sections 2.5, 2.6 and 3.4; Figs 1 and 2 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with only the oxygen supply changed, but values are in a figure and unconfirmed and which pairs differ is unknown | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: no oxygen vs added oxygen at crushing (Ogliarola) Ogliarola fruit milled in the same pilot plant with oxygen supplied to the crusher at 0, 0.2, 0.4 and 0.8 L/min | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | QDA line scale (9 expert panellists; the description of the scale structure is inconsistent and its range unclear) | Direction not given Test method described; result for this comparison not reported |
| The text says only pungency differed significantly in Ogliarola and gives no test result for bitterness (nor does it say there was no significant difference). The sentence on bitterness tending to fall with more oxygen does not separate cultivars Where: Sections 2.5, 2.6 and 3.4; Figs 1 and 2 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with only the oxygen supply changed, but neither the test result nor the values for bitterness can be confirmed | |||||
Nucciarelli 2024 sensory only
Extra Virgin Olive Oil from Stoned Olives with Oxygen Supply during Processing: Impact on Volatile and Phenolic Fraction and Sensory Characteristics. Foods 13(19):3073 — doi:10.3390/foods13193073
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1, 2.6, 2.7 and 3.4; the legends of Figs 1–4); figures not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Peranzana and Coratina fruit; University of Perugia industrial pilot plant (300 kg/h)
- Processing and cooking
- Hammer crushing or destoning, each with oxygen at 0 or 0.2 L/min; malaxation fixed at 25 °C for 30 min; 2 replicate trials each
- How it was served or eaten
- Not given (stated as following Veneziani et al.)
- Who rated, on what scale
- Trained panel, QDA; panel size, scale range and final aggregation not stated in the text (following Veneziani et al.); ANOVA with Tukey
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Malaxation and extraction: normal crushing vs destoning (Peranzana, both without oxygen) [direction of this pair unconfirmed] Peranzana fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | unstructured QDA scale (trained panel; size and range not stated in the text) | Direction not given Tested; significance reported, but which pair differs is unclear |
| As a tendency across processes, the text says Peranzana bitterness and pungency were higher with destoning and related negatively to oxygen addition. Which value is larger for this pair, both without oxygen, was not checked because the figure was not obtained. The figure legend states only that processes differed significantly (p<0.05); which pairs differ is unconfirmed Where: Sections 2.1, 2.6, 2.7 and 3.4; Figs 1–4 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with only the breaking method changed (both without oxygen) and malaxation fixed, but the direction in the text is a tendency across processes, and the values, direction and significance for this pair are in a figure and unconfirmed | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: no oxygen vs oxygen 0.2 L/min (Peranzana, both with normal crushing) [direction of this pair unconfirmed] Peranzana fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | unstructured QDA scale (trained panel; size and range not stated in the text) | Direction not given Tested; significance reported, but which pair differs is unclear |
| As a tendency across processes, the text says Peranzana bitterness and pungency related negatively to oxygen addition. Which value is larger for this pair, both with normal crushing, was not checked because the figure was not obtained. The figure legend states only that processes differed significantly (p<0.05); which pairs differ is unconfirmed Where: Sections 2.1, 2.6, 2.7 and 3.4; Figs 1–4 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with only oxygen changed (both with normal crushing) and malaxation fixed, but the direction in the text is a tendency across processes, and the values, direction and significance for this pair are in a figure and unconfirmed | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: normal crushing vs destoning (Coratina, both without oxygen) [direction of this pair unconfirmed] Coratina fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | unstructured QDA scale (trained panel; size and range not stated in the text) | Direction not given Tested; significance reported, but which pair differs is unclear |
| In describing the principal component analysis, the text says bitterness and pungency were higher in oils from destoning (a tendency across processes). Which value is larger for this pair, both without oxygen, was not checked because the figure was not obtained. The figure legend states only that processes differed significantly (p<0.05); which pairs differ is unconfirmed Where: Sections 2.1, 2.6, 2.7 and 3.4; Figs 1–4 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with only the breaking method changed (both without oxygen) and malaxation fixed, but the direction in the text is a tendency across processes, and the values, direction and significance for this pair are in a figure and unconfirmed | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: no oxygen vs oxygen 0.2 L/min (Coratina, both with normal crushing) [direction of this pair unconfirmed] Coratina fruit milled in the same pilot plant (300 kg/h) with malaxation fixed at 25 °C for 30 min; of the 4 combinations of breaking method (normal crushing or destoning) and oxygen (0 or 0.2 L/min), the 2 in the label are compared | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | unstructured QDA scale (trained panel; size and range not stated in the text) | Direction not given Tested; significance reported, but which pair differs is unclear |
| The text does not say which way Coratina bitterness moved with oxygen. The figure legend states only that processes differed significantly (p<0.05); which pairs differ is unconfirmed Where: Sections 2.1, 2.6, 2.7 and 3.4; Figs 1–4 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with only oxygen changed (both with normal crushing) and malaxation fixed, but the direction in the text is a tendency across processes, and the values, direction and significance for this pair are in a figure and unconfirmed | |||||
Manganiello 2021 sensory only
Effects of Ultrasound Technology on the Qualitative Properties of Italian Extra Virgin Olive Oil. Foods 10(11):2884 — doi:10.3390/foods10112884
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1–2.3, 3.1 and 3.4; Table 1E; the Fig. 8 legend); Fig. 8 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Peranzana and Coratina (bought in Apulia) and Canino (Lazio) fruit, ripeness index 0.88–1.04; about 200 kg per trial
- Processing and cooking
- 4 processes, normal crushing, ultrasound, destoning and destoning plus ultrasound, 3 replicates each; malaxation at 25 °C, two-phase decanter
- How it was served or eaten
- Not given
- Who rated, on what scale
- CREA Pescara panel (size not given), 0.0–10.0 scale; two-way ANOVA of cultivar and process with Tukey (means of 3 replicates)
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: without vs with ultrasound (Peranzana, Canino, Coratina) [direction from text; significance across processes] About 200 kg of fruit per process trial, milled by normal crushing with or without ultrasound (3 replicates each per cultivar; malaxation at 25 °C, two-phase decanter) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | 0.0–10.0 scale (CREA Pescara panel, size not given; mean of 3 replicates) | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction from the text (ultrasound accentuated bitterness, pungency and artichoke). In the two-way ANOVA of Table 1E, both the process main effect and its interaction with cultivar were p<0.001 for bitterness. Pairwise test results per cultivar cannot be confirmed from the text and figure legend (the Fig. 8 image was not obtained). The cultivars also came from different regions Where: Sections 2.1–2.3, 3.1 and 3.4; Table 1E; Fig. 8 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Same fruit with and without ultrasound, but values are in a figure and unconfirmed and pairwise differences per cultivar are unknown | |||||
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: normal crushing vs destoning plus ultrasound (Coratina) [direction from text; significance across processes] Coratina fruit, about 200 kg per process trial, milled by normal crushing, or destoned and then ultrasonicated (3 replicates each; malaxation at 25 °C, two-phase decanter) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | 0.0–10.0 scale (CREA Pescara panel, size not given; mean of 3 replicates) | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction from the text (only for Coratina, destoning combined with ultrasound tended to lower bitterness compared with the other processes). The interaction in the ANOVA was p<0.001, but the test result for this pair cannot be confirmed from the text and figure legend (the Fig. 8 image was not obtained) Where: Sections 2.1–2.3, 3.1 and 3.4; Table 1E; Fig. 8 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Destoning and ultrasound change together, and values are in a figure and unconfirmed | |||||
Cecchi 2019 sensory only
Implementation of the Sono-Heat-Exchanger in the Extra Virgin Olive Oil Extraction Process: End-User Validation and Analytical Evaluation. Molecules 24(13):2379 — doi:10.3390/molecules24132379
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1, 2.4, 3.2, 3.3 and 3.7; the supplementary material description); the sensory supplementary Fig. S1 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Homogeneous fruit lots of Coratina, Peranzana, Ogliarola and Cellina di Nardò at 3 mills in Apulia (2017–2018, 23 oils in all)
- Processing and cooking
- Lots divided into 800 kg portions and processed alternately with the sono-heat-exchanger and 0 min malaxation, or without it and 30 min malaxation (the text gives the temperature as both 24 °C and 25 °C)
- How it was served or eaten
- Not given
- Who rated, on what scale
- 11 professional tasters of the University of Bari, IOC method; scale range and whether means or medians not stated; the statistics section gives one-way ANOVA with t tests
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Pulsed electric fields and ultrasound: conventional (30 min malaxation) vs sono-heat-exchanger (0 min malaxation) [direction from text; sensory figure of 2 samples] Homogeneous fruit lots divided into 800 kg portions, processed alternately with the sono-heat-exchanger and 0 min malaxation or without it and 30 min malaxation (the text gives the temperature as both 24 °C and 25 °C) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | IOC method (11 tasters of the University of Bari; scale range and mean or median not stated) | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Direction from the text (ultrasound samples 20% more bitter; conventional samples more pungent). The sensory supplementary Fig. S1 shows 2 samples from the same fruit lot and was not obtained; it cannot be confirmed as the sensory result for all 23 oils. The effects of ultrasound and of dropping malaxation cannot be separated Where: Sections 2.1, 2.4, 3.2, 3.3 and 3.7; supplementary material description For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same lot was split, but ultrasound and 0 vs 30 min malaxation change together; values are in a supplementary figure and unconfirmed, and which samples they represent cannot be confirmed from the text | |||||
Ben-Hassine 2022 sensory only
Effect of processing technology on chemical, sensory, and consumers' hedonic rating of seven olive oil varieties. Food Science & Nutrition 10(3):863 — doi:10.1002/fsn3.2717
- How deeply checked
- Checked in full text — Full text via Europe PMC (methods on samples, panel and statistics; Table 1; sensory discussion) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- 5 Tunisian and 2 foreign cultivars (Arbequina, Coratina); one orchard per cultivar, ripeness index 3.5 (2017/18)
- Processing and cooking
- Mixed fruit of each cultivar split into equal weights for a press (sp) and a three-phase decanter (3ph); the methods section swaps the continuous/discontinuous labels relative to the abstract
- How it was served or eaten
- IOC tasting glass
- Who rated, on what scale
- 11 trained judges of the Cap Bon panel (IOC recognised), IOC method; the meaning of ± and whether means or medians are not stated; the letters in Table 1 compare all 14 samples at once (Tukey)
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Arbequina) Arbequina: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 1.70 | 1.50 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition before "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 1, press 1.70 (cd) and three-phase 1.50 (cd) share a letter: not significant (which does not mean the same). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Chemchali) Chemchali: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 3.56 | 2.53 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition before "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 1, press 3.56 (ab) and three-phase 2.53 (bc) share a letter: not significant (which does not mean the same). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Chemlali) Chemlali: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 1.00 | 1.80 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition after "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 1, press 1.00 (de) and three-phase 1.80 (cd) share a letter: not significant (which does not mean the same). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Chetoui) Chetoui: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 0.00 | 3.83 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition after "vs" more bitter Tested, significant |
| In Table 1, press 0.00 (e) and three-phase 3.83 (a) carry different letters: significant (p<0.05). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone. The text gives no reason for the press bitterness of 0.00 Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Coratina) Coratina: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 3.50 | 4.40 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition after "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 1, press 3.50 (ab) and three-phase 4.40 (a) share a letter: not significant (which does not mean the same). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Leguim) Leguim: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 0.00 | 2.43 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition after "vs" more bitter Tested, significant |
| In Table 1, press 0.00 (e) and three-phase 2.43 (c) carry different letters: significant (p<0.05). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone. The press oil had a free acidity of 1.42%, and the text gives no reason for the press bitterness of 0.00 Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
| Bitterness intensity (sensory) | Malaxation and extraction: press vs three-phase decanter (Zalmati) Zalmati: Fruit from one orchard (ripeness index 3.5, 2017/18) mixed and split into equal weights for a press and a three-phase decanter (1 of 7 cultivars) | 2.30 | 1.80 | IOC-method score (11 trained judges of the Cap Bon panel; the meaning of ± and whether means or medians not stated) | Condition before "vs" more bitter Tested, not significant |
| Direction shows which published value is larger. In Table 1, press 2.30 (c) and three-phase 1.80 (cd) share a letter: not significant (which does not mean the same). The letters in Table 1 compare all 14 samples at once (Tukey), not a test of the 2 samples of one cultivar alone Where: Methods (samples, panel, statistics); Table 1; sensory discussion For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — Mixed fruit of each cultivar split into equal weights with only the extraction system changed, rated by the same panel, with a test; the letters, however, compare all 14 samples at once | |||||
Brkić Bubola 2019 sensory only
Effect of Different Clarification Methods on Volatile Aroma Compound Composition of Virgin Olive Oil. Food Technology and Biotechnology 57(4):503 — doi:10.17113/ftb.57.04.19.6401
- How deeply checked
- Checked in full text — Full text via Europe PMC (methods; results "The effect of oil filtration" and "Effect of six months of storage…"; Tables 4 and 5; legends of Figs 1–3); Fig. 1 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Freshly produced Buža and Istarska bjelica oils (October 2014, same orchard, ripeness RI=2, two-phase decanter, malaxation 35 min at 25 °C)
- Processing and cooking
- The same oil filtered through a cellulose filter press or left unfiltered (3 times each); unfiltered oil left to settle naturally for 45 days at 16 °C, decanted from the sediment, and stored for 6 months at 16 °C with the filtered oil
- How it was served or eaten
- Not given
- Who rated, on what scale
- 8 trained assessors (5 women, 3 men), IOC method with added descriptors; scale range for bitterness and whether means or medians unclear (the 9-point scale is for the overall score); one-way ANOVA with Tukey
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Filtration and racking: unfiltered vs filtered (Istarska bjelica, fresh) [significance from text; filtered value unconfirmed] Istarska bjelica; The same freshly produced oil filtered through a cellulose filter press or left unfiltered (3 times each) | 5.2 | Figure not obtained, so values unconfirmed | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | Condition before "vs" more bitter Tested, significant |
| From the text: filtration significantly lowered bitterness (Tukey, p<0.05). The size of the fall is given as "about 1.7% units of intensity", an odd unit, so it is not used as a value. The filtered value is in Fig. 1 and unconfirmed Where: Methods; results "The effect of oil filtration" and "Effect of six months of storage of filtered or naturally sedimented/decanted oil"; Fig. 1 (not obtained) and Fig. 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — The same fresh oil split into filtered and unfiltered, rated by the same panel, with a significant fall stated in the text; the filtered value, however, is in a figure and unconfirmed | |||||
| Bitterness intensity (sensory) | Filtration and racking: unfiltered vs filtered (Buža, fresh) Buža; The same freshly produced oil filtered through a cellulose filter press or left unfiltered (3 times each) | 2.5 | Figure not obtained, so values unconfirmed | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | Direction not given Test method described; result for this comparison not reported |
| The text gives no test result for Buža bitterness before and after filtration (only a sentence that changes in volatile indices matched the sensory changes; it does not say there was no significant difference) Where: Methods; results "The effect of oil filtration" and "Effect of six months of storage of filtered or naturally sedimented/decanted oil"; Fig. 1 (not obtained) and Fig. 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil was split, but neither the test result nor the filtered value for bitterness can be confirmed | |||||
| Bitterness intensity (sensory) | Filtration and racking: filtered vs natural sedimentation and decanting (Istarska bjelica, after 6 months) [direction from text] Istarska bjelica; Filtered oil and oil left to settle naturally for 45 days at 16 °C and decanted from the sediment, compared after 6 months of storage at 16 °C | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Direction from the text (bitterness and pungency higher in the sedimented and decanted oil, bitterness especially). No test result for bitterness is given for this pair Where: Methods; results "The effect of oil filtration" and "Effect of six months of storage of filtered or naturally sedimented/decanted oil"; Fig. 1 (not obtained) and Fig. 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil split between 2 clarification methods and stored under the same conditions, but values are in a figure and unconfirmed and there is no test result for bitterness | |||||
| Bitterness intensity (sensory) | Filtration and racking: filtered vs natural sedimentation and decanting (Buža, after 6 months) Buža; Filtered oil and oil left to settle naturally for 45 days at 16 °C and decanted from the sediment, compared after 6 months of storage at 16 °C | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | IOC method with added descriptors (8 trained assessors; scale range and mean or median for bitterness unclear) | Direction not given Test method described; result for this comparison not reported |
| The text says positive attributes were slightly higher in the sedimented and decanted oil, but also that bitterness and pungency intensities were similar. No test result for bitterness is given Where: Methods; results "The effect of oil filtration" and "Effect of six months of storage of filtered or naturally sedimented/decanted oil"; Fig. 1 (not obtained) and Fig. 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil split between 2 clarification methods and stored under the same conditions, but values are in a figure and unconfirmed and there is no test result for bitterness | |||||
Guerrini 2020 sensory only
Understanding Olive Oil Stability Using Filtration and High Hydrostatic Pressure. Molecules 25(2):420 — doi:10.3390/molecules25020420
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.2.1, 3 and 4.1–4.4; Table 2) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Frantoio fruit (Chianti, 4 trials in November 2017, about 300 kg each); malaxation 20 min at 18 °C, two-phase decanter
- Processing and cooking
- Oil from the decanter split immediately: half filtered (filter press), half left unfiltered; each split again with or without high-pressure treatment (608 MPa); stored in 250 mL transparent PET bottles at 20 °C under 1900 lux for 8 h a day, for 15 days, 1 month and 6 months
- How it was served or eaten
- Not given (IOC method)
- Who rated, on what scale
- 8 trained panellists (5 men, 3 women; Ministry taste commission), IOC method; Table 2 gives means ± SD of 4 trials (integers); scale range not stated; three-way ANOVA with Tukey
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Filtration and racking: unfiltered vs filtered (Frantoio, after 15 days, no high pressure) [significance of this pair unconfirmed] Oil from the decanter split immediately in half, one half filtered through a filter press; both without high-pressure treatment, 15 days in transparent PET at 20 °C and 1900 lux | 3 | 5 | the source gives mean ± SD of 4 trials; the mean (integer) is shown here (8 trained panellists, IOC method, scale range not stated) | Condition after "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction shows which published value is larger. The text says the filtered oil was more bitter after 15 days and that there were no significant differences after 1 and 6 months, but within a design that includes high pressure, the significance of this pair without high pressure (3 and 5) alone is not shown. In the three-way ANOVA, bitterness was significant for filtration (p<0.01), storage time (p<0.001) and their interaction (p<0.05), not for high pressure. The bitterness row of the table has no pairwise letters. With high pressure: unfiltered 3, filtered 4 Where: Section 2.2.1; section 3; sections 4.1–4.4; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Usable — The same oil split in half immediately with only filtration changed, rated by the same panel; the significance in the text concerns filtration at 15 days, and that of this pair without high pressure alone cannot be confirmed; values are rounded to integers | |||||
| Bitterness intensity (sensory) | Oil storage: 15 days vs 6 months (Frantoio, filtered oil) [significance is the time main effect] Filtered Frantoio oil; Transparent 250 mL PET bottles at 20 °C under 1900 lux for 8 h a day; no high-pressure treatment; rated at 15 days, 1 month and 6 months | 5 | 2 | the source gives mean ± SD of 4 trials; the mean (integer) is shown here (8 trained panellists, IOC method, scale range not stated) | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction shows which published value is larger. At 1 month: 2. The text says bitterness fell significantly with storage in all oils, but the storage-time main effect (p<0.001) is not taken as the p for these 2 time points alone. In the three-way ANOVA, bitterness was significant for filtration (p<0.01), storage time (p<0.001) and their interaction (p<0.05), not for high pressure. The bitterness row of the table has no pairwise letters Where: Section 2.2.1; section 3; sections 4.1–4.4; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no test for the pair of time points, and the bottles were transparent and lit | |||||
| Bitterness intensity (sensory) | Oil storage: 15 days vs 6 months (Frantoio, unfiltered oil) [significance is the time main effect] Unfiltered Frantoio oil; Transparent 250 mL PET bottles at 20 °C under 1900 lux for 8 h a day; no high-pressure treatment; rated at 15 days, 1 month and 6 months | 3 | 1 | the source gives mean ± SD of 4 trials; the mean (integer) is shown here (8 trained panellists, IOC method, scale range not stated) | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction shows which published value is larger. At 1 month: 2. Only this oil developed fusty and rancid defects during storage. The text says bitterness fell significantly with storage in all oils, but the storage-time main effect (p<0.001) is not taken as the p for these 2 time points alone. In the three-way ANOVA, bitterness was significant for filtration (p<0.01), storage time (p<0.001) and their interaction (p<0.05), not for high pressure. The bitterness row of the table has no pairwise letters Where: Section 2.2.1; section 3; sections 4.1–4.4; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no test for the pair of time points, and the bottles were transparent and lit | |||||
Díez-Betriu 2023 sensory only
Subzero Temperature Storage to Preserve the Quality Attributes of Veiled Virgin Olive Oil. Foods 12(6):1228 — doi:10.3390/foods12061228
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1, 2.3, 2.4, 3.4 and 3.5; Tables 1 and 2; the Fig. 5 legend); Fig. 5 and supplementary tables not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- 2 Picual oils produced on the same day from the same fruit batch (two-phase decanter); one filtered by the producer through cellulose (FO), the other unfiltered (UO)
- Processing and cooking
- Stored in the dark at room temperature, 4 °C and −20 °C (slow and fast freezing) for 24 months; a further comparison thawed oils after 12 months at −20 °C and kept them at room temperature for 6 months; the whole experiment was done twice
- How it was served or eaten
- Not given (EU method)
- Who rated, on what scale
- Official Tasting Panel of Catalonia, 0–10, panel medians; tables give means of 2 experimental replicates
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Filtration and racking: unfiltered vs filtered (Picual, start of storage) Produced on the same day from the same fruit batch, one filtered by the producer through cellulose; sampled 7 days after production; moisture and volatile matter 0.376% unfiltered, 0.036% filtered | 4.4 | 4.9 | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. In the initial characterisation of Table 1, no test result for this difference is given Where: Section 2.1; section 3.4; Table 1 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Oils from the same day and fruit batch, one filtered by the producer, but whether they were split at the same point is not stated, and there is no test result for this difference | |||||
| Bitterness intensity (sensory) | Oil storage: start vs 6 months at room temperature (Picual, unfiltered oil) Unfiltered Picual oil; glass bottles in the dark at room temperature for 6 months (the non-frozen control in Table 2) | 4.4 | 3.6 | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. The p in Table 2 (0.203) is for the interaction of thawing and time, not a test of time alone. Oil frozen for 12 months and thawed went from 4.4 to 4.1 Where: Sections 2.1–2.4, 3.4 and 3.5; Table 2; Fig. 5 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no test result for time alone | |||||
| Bitterness intensity (sensory) | Oil storage: start vs 6 months at room temperature (Picual, filtered oil) Filtered Picual oil; glass bottles in the dark at room temperature for 6 months (the non-frozen control in Table 2) | 4.9 | 5.2 | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. The p in Table 2 (0.109) is for the interaction of thawing and time, not a test of time alone. Oil frozen for 12 months and thawed was 4.9 and 4.9 Where: Sections 2.1–2.4, 3.4 and 3.5; Table 2; Fig. 5 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no test result for time alone | |||||
| Bitterness intensity (sensory) | Oil storage: −20 °C vs room temperature or 4 °C for 24 months (Picual, unfiltered oil) [direction from text; significance is the interaction] Unfiltered Picual oil kept in the dark at −20 °C (slow and fast freezing) or at room temperature or 4 °C for 24 months | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | mean of 2 experimental replicates of panel medians (Official Tasting Panel of Catalonia, 0–10) | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction from the text (positive attributes of the unfiltered oil fell most at room temperature, more gradually at 4 °C, and were preserved at −20 °C). Fig. 5 shows the interaction of storage condition and time (p≤0.05), but pairwise differences were not confirmed. For the filtered oil, bitterness is said to have been maintained or to have fallen slightly Where: Sections 2.1–2.4, 3.4 and 3.5; Table 2; Fig. 5 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil stored at different temperatures only, but values are in a figure and unconfirmed and pairwise differences are unknown | |||||
Ciafardini 2022 sensory only
Microbiological and Enzymatic Activity Modulates the Bitter Taste Reduction in Decanted Coratina Olive Oil. Foods 11(6):867 — doi:10.3390/foods11060867
- How deeply checked
- Checked in full text — Full text via Europe PMC (section 3.4; Tables 1, 6, 7) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-21.
- Samples
- New Coratina oil from Italy held in 3 tanks of 200 L under nitrogen
- Processing and cooking
- Left to settle for 3 months (racked monthly); the authors attribute breakdown of bitter compounds to enzymes and yeasts in the oil
- How it was served or eaten
- Not given (not read for this table)
- Who rated, on what scale
- A nationally recognised panel (size not given); bitterness on a 0–5 descriptive scale, pungency separately; total phenols (HPLC, tyrosol equivalents) and K225, an absorbance index at 225 nm
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking) The same freshly produced Coratina oil held under nitrogen in 3 stainless steel tanks of 200 L and sampled at 0, 30, 60 and 90 days; sludge drained and headspace replaced with nitrogen at each sampling | 4.8 | 3.2 | median on a 0 (absent) to 5 (highest) scale (recognised panel, size not given) | Condition before "vs" more bitter Tested, significant |
| In Table 6 (Duncan, p<0.05), 0 days (a) and 90 days (c) carry different letters. At 30 days (4.6) the letter is shared with 0 days; 60 days was 3.8 (b). There is no unracked control at the same times, so the passage of time and racking cannot be separated. Values after 7 months of storage, 4.0 to 3.0, are in a separate column (no test between the 2 columns is reported). This is the same pair as cz-settle on the existing olive oil bitterness page, shown in reverse order Where: Sections 2.1, 2.2, 2.10 and 3.4; Table 6 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, with a test, but there is no unracked control at the same times, so time and racking cannot be separated | |||||
Brkić Bubola 2020 sensory only
Olive Fruit Refrigeration during Prolonged Storage Preserves the Quality of Virgin Olive Oil Extracted Therefrom. Foods 9(10):1445 — doi:10.3390/foods9101445
- How deeply checked
- Checked in full text — Full text via Europe PMC (section 2; section 3.3; the Fig. 2 legend); Fig. 2 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Hand-picked Istarska bjelica and Rosinjola fruit (2016, same orchard); 12 batches of 3 kg per cultivar
- Processing and cooking
- Milled immediately after harvest (control) or after 7 days at room temperature (22 ± 4 °C), +4 °C or −20 °C; hammer crusher, malaxation 45 min at 25 °C
- How it was served or eaten
- Not given
- Who rated, on what scale
- 8 trained assessors of an accredited panel (5 women, 3 men); Fig. 2 gives means of the medians of 3 technical replicates; the statistics section gives ANOVA with Tukey for chemical and sensory data, but no test result for bitterness can be confirmed from the text and figure legend (figure image not obtained)
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Fruit storage and handling: immediately after harvest vs fruit kept 7 days (Istarska bjelica) [direction from text] Istarska bjelica fruit milled immediately after harvest or after 7 days at room temperature (22 ± 4 °C), +4 °C or −20 °C (batches of 3 kg) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | mean of the medians of 3 technical replicates (8 trained assessors; scale range not stated in the text) | Depends on the combination Test method described; result for this comparison not reported |
| Direction from the text (oil from fruit kept 7 days was in most cases slightly less bitter, but for this cultivar +4 °C was similar to the control). No individual test result for bitterness can be confirmed from the text and figure legend (the Fig. 2 image was not obtained). Oils from fruit kept at room temperature and at −20 °C had defects and did not qualify as extra virgin Where: Section 2; section 3.3; Fig. 2 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Fruit from the same harvest split with only the holding conditions changed, but values are in a figure and unconfirmed and there is no test result for bitterness | |||||
| Bitterness intensity (sensory) | Fruit storage and handling: immediately after harvest vs fruit kept 7 days (Rosinjola) [direction from text] Rosinjola fruit milled immediately after harvest or after 7 days at room temperature (22 ± 4 °C), +4 °C or −20 °C (batches of 3 kg) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | mean of the medians of 3 technical replicates (8 trained assessors; scale range not stated in the text) | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Direction from the text (oil from fruit kept 7 days was in most cases slightly less bitter; the only exception was +4 °C for the other cultivar). No individual test result for bitterness can be confirmed from the text and figure legend (the Fig. 2 image was not obtained). Oils from fruit kept at room temperature and at −20 °C had defects and did not qualify as extra virgin Where: Section 2; section 3.3; Fig. 2 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Fruit from the same harvest split with only the holding conditions changed, but values are in a figure and unconfirmed and there is no test result for bitterness | |||||
Boudebouz 2023 sensory only
Effect of Hopper Loading on the Formation of Alkyl Alcohols in Olive Fruits and Its Relationship with Sensory Quality Losses of Virgin Olive Oil. Foods 12(13):2633 — doi:10.3390/foods12132633
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1–2.5, 3.1 and 3.2; Tables 1 and 2) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Arbequina (La Granadella cooperative); about 22,000 kg harvested, delivered and processed on the same day, on 3 dates (green, ripe, overripe)
- Processing and cooking
- Fruit held in a large hopper for about 3 hours and sampled 1, 10 and 20 minutes after unloading began (T1, T10, T20); the reference (Ref) was fruit kept in small boxes without passing through the hopper; oils extracted at laboratory scale (Abencor, malaxation 30 min at 24 °C)
- How it was served or eaten
- Not given (EU method)
- Who rated, on what scale
- 8 trained tasters of the Official Tasting Panel of Catalonia, 10 cm scale; the methods give medians and the table footnote means, inconsistent; Duncan tests (within each date)
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (November, green) [2 pairs higher before vs; T20 the same value] About 22,000 kg of Arbequina harvested and delivered on the same day and held in a large hopper for about 3 hours; fruit taken 1, 10 and 20 minutes after unloading began (T1, T10, T20) and fruit kept in small boxes without the hopper (Ref) milled at laboratory scale (malaxation 30 min at 24 °C); November experiment (the methods say the 26th, the results the 27th) | 3.6 | 2.7 (T1), 3.4 (T10), 3.6 (T20) | 10 cm scale (8 tasters of the Official Tasting Panel of Catalonia; the methods give medians and the table footnote means, inconsistent) | Depends on the combination Tested, only some pairs significant |
| Published values: Ref is higher than T1 and T10, and Ref and T20 have the same value. Ref (a) and T1 (b) carry different letters: significant. T10 (ab) and T20 (a) share a letter with Ref: not significant (T20 has the same value as Ref). The Duncan tests in Table 2 (p<0.05) compare within each date block, not across dates. T marks the sampling time after unloading, not storage time, and position and load also differ; Ref is also fruit kept waiting in small boxes Where: Sections 2.1–2.5 and 3.2; Tables 1 and 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Fruit delivered on the same day, but hopper position, load and time after unloading change together, and Ref is also fruit kept waiting in small boxes; not a comparison of storage time alone | |||||
| Bitterness intensity (sensory) | Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (December, ripe) [direction differs by position] About 22,000 kg of Arbequina harvested and delivered on the same day and held in a large hopper for about 3 hours; fruit taken 1, 10 and 20 minutes after unloading began (T1, T10, T20) and fruit kept in small boxes without the hopper (Ref) milled at laboratory scale (malaxation 30 min at 24 °C); experiment of 12 December | 4.2 | 4.2 (T1), 4.3 (T10), 2.1 (T20) | 10 cm scale (8 tasters of the Official Tasting Panel of Catalonia; the methods give medians and the table footnote means, inconsistent) | Depends on the combination Tested, only some pairs significant |
| Only T20 (b) differs in letter from Ref (a): significantly lower. T1 and T10 share a letter with Ref. T20 had the most damaged fruit and also showed defects. The Duncan tests in Table 2 (p<0.05) compare within each date block, not across dates. T marks the sampling time after unloading, not storage time, and position and load also differ; Ref is also fruit kept waiting in small boxes Where: Sections 2.1–2.5 and 3.2; Tables 1 and 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Fruit delivered on the same day, but hopper position, load and time after unloading change together, and Ref is also fruit kept waiting in small boxes; not a comparison of storage time alone | |||||
| Bitterness intensity (sensory) | Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (January, overripe) About 22,000 kg of Arbequina harvested and delivered on the same day and held in a large hopper for about 3 hours; fruit taken 1, 10 and 20 minutes after unloading began (T1, T10, T20) and fruit kept in small boxes without the hopper (Ref) milled at laboratory scale (malaxation 30 min at 24 °C); experiment of 7 January (overripe, frost-damaged fruit) | 2.1 | 3.2 (T1), 2.7 (T10), 2.6 (T20) | 10 cm scale (8 tasters of the Official Tasting Panel of Catalonia; the methods give medians and the table footnote means, inconsistent) | Condition after "vs" more bitter Tested, only some pairs significant |
| Direction shows which published value is larger. Only T1 (a) differs in letter from Ref (b): significantly higher. T10 and T20 (ab) share a letter with Ref. The Duncan tests in Table 2 (p<0.05) compare within each date block, not across dates. T marks the sampling time after unloading, not storage time, and position and load also differ; Ref is also fruit kept waiting in small boxes Where: Sections 2.1–2.5 and 3.2; Tables 1 and 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Fruit delivered on the same day, but hopper position, load and time after unloading change together, and Ref is also fruit kept waiting in small boxes; not a comparison of storage time alone | |||||
Antonelli 2024 sensory only
The Management of Irrigation and Potassium Fertilization to Mitigate the Effect of Light Frosts on the Phenolic and Volatile Compounds in Virgin Olive Oils. Antioxidants 13(5), article 559 — doi:10.3390/antiox13050559
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 3.1.2, 3.1.5, 3.2.3, 3.3; Figs 1, 4, 7; Table 5) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-21.
- Samples
- Chilean Arbequina: 15 irrigation, potassium and copper treatments, 3 harvests, oils from fresh fruit and from fruit frozen at −3 °C for 12 h; 180 oils in all
- Processing and cooking
- Fruit frozen or not before milling
- How it was served or eaten
- 15 mL in a standard blue glass
- Who rated, on what scale
- 9 assessors trained in the IOC method rated bitterness and pungency separately (scale range not given); compounds by HPLC in the same oils
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Fruit storage and handling: fresh fruit vs frozen fruit (Arbequina) Chilean Arbequina; for 15 cultivation treatments × 3 harvest months, fruit from each tree split in 2, one portion kept at −3 ± 1 °C for 12 hours, thawed at room temperature for 2–4 hours and then milled | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | IOC-method score (9 trained tasters; the methods give the mean of tasters and the results the average of panel medians, inconsistent) | Direction not given Tested, not significant |
| The text says bitterness and pungency did not differ significantly between oils from fresh and frozen fruit (p>0.05, Fisher LSD); no significant difference does not mean the same. Values are in Fig. 4 and unconfirmed. Fruitiness fell significantly with freezing in May and June. Kept apart from comparisons across cultivation treatments or months. This is the same comparison as an-frost on the existing olive oil bitterness page, shown in reverse order Where: Sections 2.3 and 2.9; section 3.1.5; Fig. 4 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — Fruit from the same trees split with only freezing changed, with a test, but values are in a figure and unconfirmed; a short freeze at −3 °C | |||||
Abuhabib 2025 sensory only
Evaluation of Packaging Effects on the Phenolic Profile and Sensory Characteristics of Extra Virgin Olive Oil During Storage Using Liquid Chromatography Coupled with Mass Spectrometry. Foods 14(14):2532 — doi:10.3390/foods14142532
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1–2.6 and 3.3; Table 3); Figs 2 and 3 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Corbella oil (fruit harvested on 2 dates in October 2022; filtered)
- Processing and cooking
- Stored in bag-in-box or stainless steel containers with a nitrogen headspace at 22–23 °C for 0, 6 and 12 months
- How it was served or eaten
- Not given (EU and IOC methods)
- Who rated, on what scale
- 8 tasters of the Official Tasting Panel of Catalonia, 10 cm scale; the methods give the mean of 8 tasters and the Table 3 footnote the mean of medians ± SD, inconsistent; two-way ANOVA is described, but no test result for bitterness is shown
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: 0 vs 12 months (Corbella, bag-in-box) Corbella oil (fruit harvested on 2 dates in October 2022; filtered) stored at 22–23 °C; bag-in-box | 4.60 | 4.72 | the source gives mean of medians ± SD (Table 3 footnote); the mean is shown here (the methods say the mean of 8 tasters, inconsistent; Official Tasting Panel of Catalonia, 10 cm) | Condition after "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. At 6 months: 4.20. A two-way ANOVA is described, but no test result for bitterness is shown Where: Sections 2.2, 2.5, 2.6 and 3.3; Table 3 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no test result for bitterness and the aggregation is described differently in the methods and the table | |||||
| Bitterness intensity (sensory) | Oil storage: 0 vs 12 months (Corbella, stainless steel with nitrogen) Corbella oil (fruit harvested on 2 dates in October 2022; filtered) stored at 22–23 °C; stainless steel container with a nitrogen headspace | 4.60 | 4.32 | the source gives mean of medians ± SD (Table 3 footnote); the mean is shown here (the methods say the mean of 8 tasters, inconsistent; Official Tasting Panel of Catalonia, 10 cm) | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. At 6 months: 4.40. The text says all attributes fell significantly in the stainless steel oil, but no individual test result for bitterness is shown Where: Sections 2.2, 2.5, 2.6 and 3.3; Table 3 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no test result for bitterness and the aggregation is described differently in the methods and the table | |||||
| Bitterness intensity (sensory) | Oil storage: bag-in-box vs stainless steel with nitrogen (Corbella, 12 months) Corbella oil (fruit harvested on 2 dates in October 2022; filtered) stored at 22–23 °C; containers compared at 12 months | 4.72 | 4.32 | the source gives mean of medians ± SD (Table 3 footnote); the mean is shown here (the methods say the mean of 8 tasters, inconsistent; Official Tasting Panel of Catalonia, 10 cm) | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Direction shows which published value is larger. At 6 months the values were 4.20 and 4.40, the opposite direction between containers. A two-way ANOVA is described, but no test result for bitterness is shown Where: Sections 2.2, 2.5, 2.6 and 3.3; Table 3 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil split between 2 containers, but there is no test result for bitterness and the direction is reversed at 6 months | |||||
Breschi 2025 sensory only
Chemical, Sensory, and Nutraceutical Profiling, and Shelf-Life Assessment of High-Quality Extra Virgin Olive Oil Produced in a Local Area near Florence (Italy). Molecules 30(13):2811 — doi:10.3390/molecules30132811
- How deeply checked
- Checked in full text — Full text via Europe PMC (the sensory paragraph in section 2.3.2; storage and sensory methods in sections 3.3 and 3.5; Table 10) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- 2 oils (B and P) selected from those of 12 producers near Florence
- Processing and cooking
- Stored in 250 mL or 500 mL bottles without light at room temperature below 25 °C for 0 (immediately after production), 2, 5 and 12 months; each tasting used freshly opened bottles
- How it was served or eaten
- From bottles just opened
- Who rated, on what scale
- A Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given; three-way ANOVA applied to compounds only, with no sensory test
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: immediately after production vs 12 months (oil B, 250 mL bottle) Oil B in 250 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | 3.9 | 6.0 | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | Condition after "vs" more bitter No test reported |
| Direction shows which published value is larger. At 2 months: 5.4; at 5 months: 6.2. Values from Table 10; no sensory test is reported (the three-way ANOVA covers compounds only). The text says bitterness stayed more pronounced than at the start throughout storage. The authors' suggestion that the rise in pungency may reflect sensory stabilisation typical of fresh oils is not confirmed Where: Section 2.3.2 (sensory paragraph); sections 3.3 and 3.5 (storage and sensory methods); Table 10 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no sensory test and the scale is not given | |||||
| Bitterness intensity (sensory) | Oil storage: immediately after production vs 12 months (oil B, 500 mL bottle) Oil B in 500 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | 3.9 | 6.3 | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | Condition after "vs" more bitter No test reported |
| Direction shows which published value is larger. At 2 months: 6.2; at 5 months: 5.8. Values from Table 10; no sensory test is reported (the three-way ANOVA covers compounds only). The text says bitterness stayed more pronounced than at the start throughout storage. The authors' suggestion that the rise in pungency may reflect sensory stabilisation typical of fresh oils is not confirmed Where: Section 2.3.2 (sensory paragraph); sections 3.3 and 3.5 (storage and sensory methods); Table 10 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no sensory test and the scale is not given | |||||
| Bitterness intensity (sensory) | Oil storage: immediately after production vs 12 months (oil P, 250 mL bottle) Oil P in 250 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | 2.9 | 4.3 | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | Condition after "vs" more bitter No test reported |
| Direction shows which published value is larger. At 2 months: 5.5; at 5 months: 5.6. Values from Table 10; no sensory test is reported (the three-way ANOVA covers compounds only). The text says bitterness stayed more pronounced than at the start throughout storage. The authors' suggestion that the rise in pungency may reflect sensory stabilisation typical of fresh oils is not confirmed Where: Section 2.3.2 (sensory paragraph); sections 3.3 and 3.5 (storage and sensory methods); Table 10 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no sensory test and the scale is not given | |||||
| Bitterness intensity (sensory) | Oil storage: immediately after production vs 12 months (oil P, 500 mL bottle) Oil P in 500 mL bottles, stored without light at room temperature below 25 °C; T0 is immediately after production, and each tasting used freshly opened bottles | 2.9 | 6.1 | rating by a Ministry-recognised panel (a leader and 8–12 trained assessors); scale range and whether means or medians not given | Condition after "vs" more bitter No test reported |
| Direction shows which published value is larger. At 2 months: 7.4; at 5 months: 6.4. Values from Table 10; no sensory test is reported (the three-way ANOVA covers compounds only). The text says bitterness stayed more pronounced than at the start throughout storage. The authors' suggestion that the rise in pungency may reflect sensory stabilisation typical of fresh oils is not confirmed Where: Section 2.3.2 (sensory paragraph); sections 3.3 and 3.5 (storage and sensory methods); Table 10 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time, but there is no sensory test and the scale is not given | |||||
Sanmartin 2018 sensory only
The effects of packaging and storage temperature on the shelf-life of extra virgin olive oil. Heliyon 4(11):e00888 — doi:10.1016/j.heliyon.2018.e00888
- How deeply checked
- Checked in full text — Full text via Europe PMC (methods on samples, sensory analysis and statistics; the sensory paragraph of the results; Table 2) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- The same oil kept for 63 days in stainless steel silos under nitrogen (12–18 °C)
- Processing and cooking
- Packed in greenish glass bottles (100 mL) and tinplate tins (175 mL) and stored at 6 °C and 26 °C for 125 days
- How it was served or eaten
- Not given
- Who rated, on what scale
- 10 trained assessors of the University of Pisa, QDA, 0–10, means; one-way ANOVA with LSD; bitterness values not published
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: at packaging vs after 125 days (greenish glass and tin, 6 °C and 26 °C) The same oil, kept 63 days in silos under nitrogen, packed in greenish glass bottles (100 mL) and tins (175 mL) and stored at 6 °C and 26 °C for 125 days | Values not published (data not shown) | Values not published (data not shown) | QDA, 0–10, means (10 trained assessors of the University of Pisa) | Direction not given Tested, not significant |
| The text says that under every storage condition bitterness after 125 days showed no significant change from packaging (one-way ANOVA with LSD). Values are not published. No significant difference does not mean the same, and this is not a test that the containers are equivalent. The bitterness index (BI) in Table 2 is absorbance at 225 nm, not a human rating, and is not used Where: Methods (samples, sensory, statistics); the sensory paragraph of the results; Table 2 For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time with a test, but values are not published | |||||
Sordini 2026 sensory only
Evaluating the Effect of Packaging Materials on Extra Virgin Olive Oil Quality Under Simulated Household Use and Storage Conditions. Foods 15(11):1948 — doi:10.3390/foods15111948
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1–2.4 and 3.6; Table 1; the Fig. 7 legend); Fig. 7 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Oil from a single batch of organic Moraiolo olives (Umbria, 2019/2020)
- Processing and cooking
- The same oil filled into 3 L PET, bag-in-box and tin containers at 25 °C under 500 lux for 12 h a day; opened daily with 75 mL withdrawn, for 40 days; sensory ratings on composite samples of about 160 mL pooling chemical-analysis residues, the sensory sample and the previous sampling day
- How it was served or eaten
- Samples kept at 12 °C in the dark until analysis
- Who rated, on what scale
- 10 experienced judges of the University of Perugia (4 men, 6 women), QDA, 9 cm line scale from 0 to 9, mean of 10 panellists
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: change over storage, 0–40 days (Moraiolo, opened and drawn daily; PET, bag-in-box, tin) [direction from text; significance of 0 vs 40 days unconfirmed] The same Moraiolo oil filled into 3 L PET, bag-in-box and tin containers at 25 °C under 500 lux for 12 h a day; opened daily with 75 mL withdrawn; sensory ratings used a composite sample of about 160 mL pooling chemical-analysis residues, the sensory sample and the previous sampling day, not oil taken on day 40 alone | 4.31 | Figure not obtained, so values unconfirmed | 9 cm line scale from 0 to 9, mean of 10 panellists (10 experienced judges of the University of Perugia) | Condition before "vs" more bitter Tested; significance reported, but which pair differs is unclear |
| Direction from the text. Over the 40-day storage test, a significant fall in bitterness (p<0.05) was reported for every container. The letters in Fig. 7 compare several time points within one container; as the figure was not obtained, the individual 0 vs 40 day comparison for each container was not checked. This is not a test between containers. The text says bitterness was higher in bag-in-box and tin than in PET. Sensory samples came from repeating the procedure with the same batch Where: Sections 2.1–2.4 and 3.6; Table 1; Fig. 7 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oil followed over time with a significant fall during storage reported, but the individual 0 vs 40 day comparison and the 40-day values are in a figure and unconfirmed; daily opening and withdrawal; sensory ratings on composite samples | |||||
De Santis 2024 sensory only
Stability of monovarietal Sicilian olive oils under different storage condition: Chemical composition, sensory characteristics, and consumer preference. Heliyon 10(9):e29833 — doi:10.1016/j.heliyon.2024.e29833
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1–2.2, 2.6, 2.8 and 3.5; legends of Figs 3 and 4); Figs 3 and 4 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Biancolilla and Cerasuola oils (Sicily, organic), filtered and unfiltered
- Processing and cooking
- Green glass bottles of 0.5 L saturated with nitrogen, stored in the dark at −20 ± 3 °C or 20 ± 2 °C for 0, 3, 6 and 12 months (the abstract says 18 °C)
- How it was served or eaten
- 15 mL in a blue glass warmed to 28 ± 2 °C
- Who rated, on what scale
- 8 trained judges, IOC method with minor adjustments, 10 cm scale; whether means or medians not stated; the statistics section gives two-way ANOVA with Tukey, but no test result for bitterness is shown
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: −20 °C vs room temperature for 12 months (Biancolilla and Cerasuola) [direction from text] Filtered and unfiltered Biancolilla and Cerasuola oils in nitrogen-saturated green glass bottles kept in the dark at −20 ± 3 °C or 20 ± 2 °C for 12 months (the abstract says 18 °C) | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | 10 cm scale (8 trained judges; mean or median not stated) | Condition before "vs" more bitter Test method described; result for this comparison not reported |
| Direction from the text (bitterness and pungency fell during storage, especially at room temperature and unfiltered; room temperature lowered bitterness more than freezing). Values are in Figs 3 and 4 and unconfirmed. The statistics section gives two-way ANOVA with Tukey, but no pairwise result for bitterness is given Where: Sections 2.1–2.2, 2.6, 2.8 and 3.5; Figs 3 and 4 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oils stored at different temperatures only, but values are in figures and unconfirmed and there is no pairwise test result for bitterness | |||||
Tucci 2025 sensory only
Changes in the Volatile Profile, Fruity Flavor, and Rancidity in Virgin Olive Oils During Storage by Targeted and Untargeted Analytical Approaches. Foods 14(11):1884 — doi:10.3390/foods14111884
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.2, 2.3, 2.8 and 3.1; legends of Figs 2 and 3); Fig. 3 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- Nostrana di Brisighella oils (2022/2023; integrated pest management and organic groves; 4 harvest weeks); 32 samples in all
- Processing and cooking
- Kept in a room with natural light at about 25 °C for 0, 6 and 12 months; only oils from the 1st and 4th weeks in 2 kinds of 0.75 L bottles, the rest in dark glass bottles
- How it was served or eaten
- Not given
- Who rated, on what scale
- Official DISTAL panel of the University of Bologna, 10 cm scale, medians; panel size not given; ANOVA with Tukey applied to fruitiness only
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: 0 vs 12 months (Nostrana di Brisighella) [direction from text] Nostrana di Brisighella oils from one area (2 cultivation systems × 4 harvest weeks) kept in a room with natural light at about 25 °C for 0, 6 and 12 months | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | median on a 10 cm scale (official DISTAL panel of the University of Bologna, size not given) | Condition before "vs" more bitter No test reported |
| Direction from the text (fresh olive, grass and artichoke notes and bitterness and pungency fell over time). Values are in Fig. 3 and unconfirmed. The sensory ANOVA was applied to fruitiness only, with no test for bitterness reported; the fruitiness test of Fig. 2 is not carried over to bitterness Where: Sections 2.2, 2.3, 2.8 and 3.1; Figs 2 and 3 (Fig. 3 not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oils followed over time, but values are in a figure and unconfirmed and there is no test for bitterness | |||||
Mousavi 2021 sensory only
Evolution of Extra Virgin Olive Oil Quality under Different Storage Conditions. Foods 10(8):1945 — doi:10.3390/foods10081945
- How deeply checked
- Checked in full text — Full text via Europe PMC (sections 2.1, 2.10, 2.11 and 3.8; the Fig. 6 legend); Fig. 6 not obtained Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-22.
- Samples
- 3 oils with low, medium and high phenols (same mill, filtered)
- Processing and cooking
- 250 mL amber glass bottles in the dark; ambient temperature, ambient with argon, 4 °C and −18 °C for 18 and 36 months; also rated 72 hours, 1 month and 8 months after opening
- How it was served or eaten
- Not given
- Who rated, on what scale
- Slow Food panel (5 tasters and a leader), modified IOC method, 0–10; Fig. 6 gives the median of 15 evaluations (3 replicates × 5 tasters); the statistics section gives one-way ANOVA with Tukey, but no sensory test result is given
| Measured | Comparison and condition | Condition before "vs" | Condition after "vs" | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Oil storage: −18 °C vs 4 °C for 18 months (3 oils with different phenol levels) [the text summarises all periods; direction at this point unconfirmed] 3 oils with low, medium and high phenols kept in 250 mL amber glass bottles in the dark at −18 °C or 4 °C for 18 months | Figure not obtained, so values unconfirmed | Figure not obtained, so values unconfirmed | 0–10; Fig. 6 gives the median of 15 evaluations (3 replicates × 5 tasters) (Slow Food panel, 5 tasters and a leader; modified IOC method) | Direction not given Test method described; result for this comparison not reported |
| After describing 18 months, after opening and 36 months in turn, the text summarises that of the low temperatures −18 °C preserved persistence, fruitiness, bitterness and other attributes a bit better than 4 °C. Which was more bitter for each oil at 18 months is not stated and was not checked because the figure was not obtained. Values are in radar charts (Fig. 6) and unconfirmed. The statistics section gives ANOVA with Tukey, but no sensory test result is given. The text says oils at ambient temperature deteriorated in flavour by 18 months Where: Sections 2.1, 2.10, 2.11 and 3.8; Fig. 6 (not obtained) For whether changing the extraction (crushing, malaxation, oxygen, pulsed electric fields, ultrasound, destoning, extraction system), filtration or racking, the handling of the fruit before milling, or the storage of the oil (time, temperature, container), for the same fruit (same cultivar and harvest lot) or the same oil, changes the intensity of bitterness people perceive: Limited — The same oils stored at different temperatures only, but the text summarises all periods, the 18-month values are in figures and unconfirmed, there is no test result, and the panel used a modified IOC method | |||||
What was established within an experiment
Only results observed in comparisons within one study. Results with no test shown are stated as such.
- In Navarro et al., bitterness scores of pulsed-electric-field oils were higher in the pilot trials (trial 1, 3.8 and 4.4; trial 2, 3.3 and 4.5; trial 3, 2.6 and 3.1) and lower in the industrial trial (4.85 and 4.10). In trial 1 malaxation time also differed, 90 vs 45 min, and in trial 3 decanter flow and other conditions also differed. No sensory test result is shown. [rows: Navarro 2022 Pulsed electric fields and ultrasound: no pulsed electric field with 90 min malaxation vs pulsed electric field with 45 min malaxation (Manzanilla, pilot); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, pilot); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Hojiblanca, pilot; flow also differs); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, industrial)]
- In Boffa et al. with Coratina, medians were higher with ultrasound instead of malaxation (3.9) and with a pulsed electric field after malaxation (3.9) than with conventional malaxation (3.5). Adding a pulsed electric field to ultrasound gave 3.8 (positive) and 4.0 (bipolar), not a uniform rise from ultrasound alone (3.9). The authors say bitterness was significantly higher with the new processes, but no sensory test method is given. [rows: Boffa 2024 Pulsed electric fields and ultrasound: conventional 30 min malaxation vs ultrasound instead of malaxation (Coratina, industrial) [authors state significance; test details not reported]; Boffa 2024 Pulsed electric fields and ultrasound: conventional 30 min malaxation vs malaxation followed by pulsed electric field (positive) (Coratina, industrial) [authors state significance; test details not reported]; Boffa 2024 Pulsed electric fields and ultrasound: ultrasound alone vs ultrasound plus pulsed electric field (positive) (Coratina, industrial); Boffa 2024 Pulsed electric fields and ultrasound: ultrasound alone vs ultrasound plus pulsed electric field (bipolar) (Coratina, industrial)]
- In Ben-Hassine et al. with 7 cultivars, only Chetoui (0.00 and 3.83) and Leguim (0.00 and 2.43) differed in letter between press and three-phase decanter, both higher with the three-phase decanter. The other cultivars shared letters, and among them Arbequina, Chemchali and Zalmati had higher press values. The letters compare all 14 samples at once. [rows: Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Arbequina); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Chemchali); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Chemlali); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Chetoui); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Coratina); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Leguim); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Zalmati)]
- In Brkić Bubola et al., unfiltered Istarska bjelica scored 5.2 and filtration is reported to have lowered bitterness significantly (the size of the fall is not used, as its unit in the text is odd). For Buža (2.5) no test result for bitterness before and after filtration is given. After 6 months of storage, the authors write that the sedimented and decanted Istarska bjelica oil was more bitter. [rows: Brkić Bubola 2019 Filtration and racking: unfiltered vs filtered (Istarska bjelica, fresh) [significance from text; filtered value unconfirmed]; Brkić Bubola 2019 Filtration and racking: unfiltered vs filtered (Buža, fresh); Brkić Bubola 2019 Filtration and racking: filtered vs natural sedimentation and decanting (Istarska bjelica, after 6 months) [direction from text]]
- In Ciafardini et al., 30 days (4.6) did not differ significantly from 0 days, and bitterness fell significantly at 60 days (3.8) and 90 days (3.2). Sludge was drained and nitrogen replaced at each sampling, with no unracked control. [rows: Ciafardini 2022 Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking)]
- In Boudebouz et al., compared with fruit not passed through the hopper (Ref), T1 was significantly lower at 2.7 in November, T20 significantly lower at 2.1 in December, and T1 significantly higher at 3.2 in January (Ref 3.6, 4.2 and 2.1). Comparisons are within each date only, not across dates. [rows: Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (November, green) [2 pairs higher before vs; T20 the same value]; Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (December, ripe) [direction differs by position]; Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (January, overripe)]
- In comparisons storing the same oil in different containers or at different temperatures, Abuhabib et al. with Corbella found 4.72 in bag-in-box and 4.32 in stainless steel with nitrogen at 12 months, the opposite direction between containers from 6 months (4.20 and 4.40). In Díez-Betriu et al. with Picual, 6 months at room temperature took the unfiltered oil from 4.4 to 3.6 and the filtered oil from 4.9 to 5.2. Neither shows a test result for bitterness. [rows: Abuhabib 2025 Oil storage: bag-in-box vs stainless steel with nitrogen (Corbella, 12 months); Abuhabib 2025 Oil storage: 0 vs 12 months (Corbella, bag-in-box); Abuhabib 2025 Oil storage: 0 vs 12 months (Corbella, stainless steel with nitrogen); Díez-Betriu 2023 Oil storage: start vs 6 months at room temperature (Picual, unfiltered oil); Díez-Betriu 2023 Oil storage: start vs 6 months at room temperature (Picual, filtered oil)]
- Some comparisons showed no significant difference: decanter vs vertical centrifuge outlet (Peralta et al., 2.7 and 2.6; 3.4 and 3.2), fresh vs frozen fruit (Antonelli et al.), and 125 days after packaging (Sanmartin et al.). No significant difference does not mean the same. [rows: Peralta 2024 Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (15 min malaxation trial); Peralta 2024 Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (30 min malaxation trial); Antonelli 2024 Fruit storage and handling: fresh fruit vs frozen fruit (Arbequina); Sanmartin 2018 Oil storage: at packaging vs after 125 days (greenish glass and tin, 6 °C and 26 °C)]
Candidate explanations for the differences
Conditions that differ between studies and could explain the differences in bitterness results, and the authors' interpretations. Several conditions differ at once, so which one mattered is unknown. These are candidates, not causes.
- Many authors explain changes in bitterness by rises or falls in phenolic compounds. This page does not deal with compound levels or breakdown mechanisms, and leaves the correspondence between compounds and bitterness to the olive oil bitterness comparison page; here it is only listed as the authors' interpretation, as a candidate. [rows: Leone 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Picholine, industrial); Nucciarelli 2024 Malaxation and extraction: normal crushing vs destoning (Peranzana, both without oxygen) [direction of this pair unconfirmed]; Veneziani 2023 Malaxation and extraction: no oxygen vs added oxygen at crushing (Coratina) [direction from text; significance across processes]; Brkić Bubola 2019 Filtration and racking: unfiltered vs filtered (Istarska bjelica, fresh) [significance from text; filtered value unconfirmed]]
- Filtration changes how much water and other matter remains in the oil. In Díez-Betriu et al. the unfiltered oil had more moisture and volatile matter (0.376%) than the filtered oil (0.036%). The authors consider such differences relevant to changes during storage or settling, but this page does not check that. In Guerrini et al. the filtered oil was more bitter after 15 days, and in Díez-Betriu et al. the filtered oil scored higher at the start, so unfiltered oil is not always the more bitter. [rows: Díez-Betriu 2023 Filtration and racking: unfiltered vs filtered (Picual, start of storage); Guerrini 2020 Filtration and racking: unfiltered vs filtered (Frantoio, after 15 days, no high pressure) [significance of this pair unconfirmed]; Ciafardini 2022 Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking)]
- Even with the same treatment, the direction of published values differed by cultivar or fruit condition. For press vs three-phase decanter (Ben-Hassine et al.), the three-phase decanter was higher for Chetoui and Leguim, while the press value was higher for Arbequina, Chemchali and Zalmati. For the hopper (Boudebouz et al.), the direction differed between dates with different ripeness and damage. Cultivar and fruit condition are candidate explanations for the differences. Comparisons that were significant in one cultivar but had no reported test result in another are not used as evidence of a difference by cultivar. [rows: Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Chetoui); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Leguim); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Arbequina); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Chemchali); Ben-Hassine 2022 Malaxation and extraction: press vs three-phase decanter (Zalmati); Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (November, green) [2 pairs higher before vs; T20 the same value]; Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (December, ripe) [direction differs by position]; Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (January, overripe)]
- Why the pulsed electric field went in opposite directions at pilot and industrial scale (Navarro et al.) may relate to throughput, temperature and fruit condition differing between trials, but the authors do not explain it. [rows: Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, pilot); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Manzanilla, industrial)]
What is not known — what this comparison alone cannot separate
- New technologies often change together with other conditions such as malaxation time and temperature or decanter flow (Navarro et al. trials 1 and 3; in Boffa et al. and Cecchi et al. ultrasound replaced malaxation). This comparison alone cannot separate the effect of the pulsed electric field or ultrasound itself from that of shortening or dropping malaxation. [rows: Navarro 2022 Pulsed electric fields and ultrasound: no pulsed electric field with 90 min malaxation vs pulsed electric field with 45 min malaxation (Manzanilla, pilot); Navarro 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Hojiblanca, pilot; flow also differs); Boffa 2024 Pulsed electric fields and ultrasound: conventional 30 min malaxation vs ultrasound instead of malaxation (Coratina, industrial) [authors state significance; test details not reported]; Cecchi 2019 Pulsed electric fields and ultrasound: conventional (30 min malaxation) vs sono-heat-exchanger (0 min malaxation) [direction from text; sensory figure of 2 samples]]
- In storage and settling comparisons, the passage of time overlaps with racking, opening, light and container. Ciafardini et al. had no unracked control at the same times, Sordini et al. opened and drew from containers daily, and Guerrini et al. used transparent bottles under light. Each study's storage conditions cannot be applied to storage at home or in shops in general. [rows: Ciafardini 2022 Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking); Sordini 2026 Oil storage: change over storage, 0–40 days (Moraiolo, opened and drawn daily; PET, bag-in-box, tin) [direction from text; significance of 0 vs 40 days unconfirmed]; Guerrini 2020 Oil storage: 15 days vs 6 months (Frantoio, filtered oil) [significance is the time main effect]]
- Several studies come from the same assessment body or research group: the Official Tasting Panel of Catalonia (Díez-Betriu et al., Boudebouz et al., Abuhabib et al.), the same Croatian institute (the Brkić Bubola et al. studies), the University of Perugia (Veneziani et al., Nucciarelli et al., Sordini et al., with co-authors also on Leone et al. and Manganiello et al.), and the University of Florence (Guerrini et al., Breschi et al., Cecchi et al.). Whether the raters were the same people was not checked, but these are not counted as independent replications. Peralta et al., Ciafardini et al. and Antonelli et al. are the same studies as on the existing olive oil bitterness page and are not counted again as new evidence. [rows: Díez-Betriu 2023 Filtration and racking: unfiltered vs filtered (Picual, start of storage); Boudebouz 2023 Fruit storage and handling: fruit not passed through the hopper vs fruit from the hopper (November, green) [2 pairs higher before vs; T20 the same value]; Abuhabib 2025 Oil storage: bag-in-box vs stainless steel with nitrogen (Corbella, 12 months); Brkić Bubola 2019 Filtration and racking: unfiltered vs filtered (Istarska bjelica, fresh) [significance from text; filtered value unconfirmed]; Brkić Bubola 2020 Fruit storage and handling: immediately after harvest vs fruit kept 7 days (Istarska bjelica) [direction from text]; Veneziani 2023 Malaxation and extraction: no oxygen vs added oxygen at crushing (Coratina) [direction from text; significance across processes]; Nucciarelli 2024 Malaxation and extraction: normal crushing vs destoning (Peranzana, both without oxygen) [direction of this pair unconfirmed]; Sordini 2026 Oil storage: change over storage, 0–40 days (Moraiolo, opened and drawn daily; PET, bag-in-box, tin) [direction from text; significance of 0 vs 40 days unconfirmed]; Guerrini 2020 Filtration and racking: unfiltered vs filtered (Frantoio, after 15 days, no high pressure) [significance of this pair unconfirmed]; Breschi 2025 Oil storage: immediately after production vs 12 months (oil B, 250 mL bottle); Cecchi 2019 Pulsed electric fields and ultrasound: conventional (30 min malaxation) vs sono-heat-exchanger (0 min malaxation) [direction from text; sensory figure of 2 samples]; Peralta 2024 Malaxation and extraction: decanter outlet vs vertical centrifuge outlet (15 min malaxation trial); Ciafardini 2022 Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking); Antonelli 2024 Fruit storage and handling: fresh fruit vs frozen fruit (Arbequina)]
- Scales (0–10 lines, 0–5 categories, the IOC method and others) and whether medians or means are used differ by study, and some studies do not give panel size or scale range. Values are not compared across studies. Bitterness is a separate attribute from pungency (throat irritation) and fruitiness, and this page lines up bitterness only. [rows: Ciafardini 2022 Filtration and racking: 0 vs 90 days of settling (Coratina, under nitrogen with monthly racking); Díez-Betriu 2023 Filtration and racking: unfiltered vs filtered (Picual, start of storage); Leone 2022 Pulsed electric fields and ultrasound: without vs with pulsed electric field (Picholine, industrial)]
- This page lines up the bitterness people perceived in studies of extraction and storage; it is not advice on choosing, buying or storing olive oil. [rows: Sanmartin 2018 Oil storage: at packaging vs after 125 days (greenish glass and tin, 6 °C and 26 °C); Breschi 2025 Oil storage: immediately after production vs 12 months (oil B, 250 mL bottle)]
How studies and rows were counted
The number of evidence rows is not the number of studies. Table rows, ledger evidence rows, papers and research groups are counted separately. Studies assessed by the same body (the Official Tasting Panel of Catalonia) or from the same institute or university (the Croatian institute, the University of Perugia, the University of Florence) are each counted as one research group. Studies that also appear on the existing olive oil bitterness page use the same study records and are not counted again as new evidence. The number of research groups shown in the table below is the number of categories in the ledger, not the number of independent replications; co-authors and assessment bodies overlap across some studies, so it does not guarantee independence.
- Sources in the table: 23, of which 23 have results on people's bitterness ratings in this table; for the others, only results on something else (compounds, smell) are shown, or they are used only for context.
- Rows in the table (study × measured result): 57. Rows on perceived bitterness: 57.
- Evidence rows in the lab's ledger these rows rest on: 0. One paper can supply several rows. Rows without a ledger evidence row come from other tables of the same papers, or from sources newly read for this question.
- Research groups among the studies with bitterness results in this table, as grouped in the ledger: 14 (reports from the same lab count as 1; co-authors and affiliations can overlap, so this is not a count of independent replications).
What we looked at
The sources examined for this question and why each was included or excluded. We searched Europe PMC for studies combining olive oil malaxation, crushing, destoning, pulsed electric fields, ultrasound, oxygen, filtration, racking, storage, containers or fruit storage with human ratings of bitterness, searched J-STAGE for Japanese- and English-language studies, and added the sources already in the lab's ledger. Comparisons in which the trees or ripeness of the fruit changed with the condition, observational studies grouping separate batches by days, and studies whose scale cannot be read as bitterness intensity without caution were kept as references outside the main table. Studies with no human bitterness rating (only chemical analysis, electronic nose or absorbance indices, for example), studies that rated the bitterness of the fruit rather than the oil, and comparisons outside the scope such as fruit washing were excluded. The search described here is a record, not a claim that nothing was missed.
| Source | Decision | Why |
|---|---|---|
| Olive Oil (Royal Cultivar) from Mill Obtained by Short Time Malaxation and Early Ripening Stage (2024) doi | Included in the table | The comparison of decanter and vertical centrifuge outlets for the same batch is included; the 15 vs 30 min malaxation comparison was on different days and batches with temperature and fruit oil content also differing, so it is not a row here (it is covered on the existing olive oil bitterness page); read in full |
| Investigation on the Effects of a Pulsed Electric Field (PEF) Continuous System Implemented in an Industrial Olive Oil Plant (2022) doi | Included in the table | Pulsed electric field on or off with homogeneous lots at an industrial mill; read in full |
| Application of Pulsed Electric Fields to Pilot and Industrial Scale Virgin Olive Oil Extraction: Impact on Organoleptic and Functional Quality (2022) doi | Included in the table | Pulsed electric field on or off at pilot and industrial scale; the rows state that other conditions also differed in trials 1 and 3; read in full |
| Industrial Production of Bioactive Nutrient-Enhanced Extra Virgin Olive Oil under Continuous-Flow Ultrasound and Pulsed Electric Field Treatment (2024) doi | Included in the table | Combinations of malaxation, ultrasound and pulsed electric field with the same batch; the storage sensory data (Fig. 6) were not read; read in full |
| Effect of Controlled Oxygen Supply during Crushing on Volatile and Phenol Compounds and Sensory Characteristics in Coratina and Ogliarola Virgin Olive Oils (2023) doi | Included in the table | Oxygen supply at crushing compared; values in figures, not obtained; read in full |
| Extra Virgin Olive Oil from Stoned Olives with Oxygen Supply during Processing: Impact on Volatile and Phenolic Fraction and Sensory Characteristics (2024) doi | Included in the table | Crushing vs destoning and with or without oxygen; values in figures, not obtained; read in full |
| Effects of Ultrasound Technology on the Qualitative Properties of Italian Extra Virgin Olive Oil (2021) doi | Included in the table | Ultrasound and destoning compared; values in Fig. 8, not obtained; cultivars from different regions do not invalidate within-cultivar process comparisons, so rows were made; read in full |
| Implementation of the Sono-Heat-Exchanger in the Extra Virgin Olive Oil Extraction Process: End-User Validation and Analytical Evaluation (2019) doi | Included in the table | Sono-heat-exchanger (0 min malaxation) vs conventional (30 min); sensory values in a supplementary figure, not obtained; read in full |
| Effect of processing technology on chemical, sensory, and consumers' hedonic rating of seven olive oil varieties (2022) doi | Included in the table | Press vs three-phase decanter for 7 cultivars; consumer liking results not used; read in full |
| Effect of Different Clarification Methods on Volatile Aroma Compound Composition of Virgin Olive Oil (2019) doi | Included in the table | Filtered vs unfiltered, and filtration vs sedimentation and decanting after 6 months; Fig. 1 not obtained; read in full |
| Understanding Olive Oil Stability Using Filtration and High Hydrostatic Pressure (2020) doi | Included in the table | Filtration and storage time compared; high-pressure (hydrostatic) treatment is outside the scope of processes in this question (extraction, filtration and racking, fruit handling, oil storage), so it is not a row, and the pairs without high pressure were used; read in full |
| Subzero Temperature Storage to Preserve the Quality Attributes of Veiled Virgin Olive Oil (2023) doi | Included in the table | Filtration and storage temperature compared; 24-month values in Fig. 5, not obtained; read in full |
| Microbiological and Enzymatic Activity Modulates the Bitter Taste Reduction in Decanted Coratina Olive Oil (2022) doi | Included in the table | Settling under nitrogen with monthly racking; the same study as on the existing olive oil bitterness page; read in full |
| Olive Fruit Refrigeration during Prolonged Storage Preserves the Quality of Virgin Olive Oil Extracted Therefrom (2020) doi | Included in the table | Fruit held for 7 days at different temperatures before milling; values in Fig. 2, not obtained; read in full |
| Effect of Hopper Loading on the Formation of Alkyl Alcohols in Olive Fruits and Its Relationship with Sensory Quality Losses of Virgin Olive Oil (2023) doi | Included in the table | Fruit from a large hopper vs fruit not passed through it on 3 dates; no comparison across dates; read in full |
| The Management of Irrigation and Potassium Fertilization to Mitigate the Effect of Light Frosts on the Phenolic and Volatile Compounds in Virgin Olive Oils (2024) doi | Included in the table | Fresh vs frozen fruit; cultivation treatment comparisons not used; the same study as on the existing olive oil bitterness page; read in full |
| Evaluation of Packaging Effects on the Phenolic Profile and Sensory Characteristics of Extra Virgin Olive Oil During Storage Using Liquid Chromatography Coupled with Mass Spectrometry (2025) doi | Included in the table | The same oil stored in 2 containers for 12 months; read in full |
| Chemical, Sensory, and Nutraceutical Profiling, and Shelf-Life Assessment of High-Quality Extra Virgin Olive Oil Produced in a Local Area near Florence (Italy) (2025) doi | Included in the table | 2 oils stored in 2 bottle sizes for 12 months; read in full |
| The effects of packaging and storage temperature on the shelf-life of extra virgin olive oil (2018) doi | Included in the table | The same oil stored in 2 containers at 2 temperatures for 125 days; bitterness values not published; read in full |
| Evaluating the Effect of Packaging Materials on Extra Virgin Olive Oil Quality Under Simulated Household Use and Storage Conditions (2026) doi | Included in the table | The same oil in 3 containers opened and drawn daily for 40 days; sensory ratings on composite samples; 40-day values in Fig. 7, not obtained; read in full |
| Stability of monovarietal Sicilian olive oils under different storage condition: Chemical composition, sensory characteristics, and consumer preference (2024) doi | Included in the table | Filtration and storage temperature over 12 months; values in Figs 3 and 4, not obtained; read in full |
| Changes in the Volatile Profile, Fruity Flavor, and Rancidity in Virgin Olive Oils During Storage by Targeted and Untargeted Analytical Approaches (2025) doi | Included in the table | Oils from one area stored for 12 months; values in Fig. 3, not obtained; no test for bitterness; read in full |
| Evolution of Extra Virgin Olive Oil Quality under Different Storage Conditions (2021) doi | Included in the table | 3 oils stored at different temperatures; a panel size differing from the IOC method was not by itself a reason to exclude, so a row was made; values in Fig. 6, not obtained; read in full |
| Aromatic, Sensory, and Fatty Acid Profiles of Arbequina Extra Virgin Olive Oils Produced Using Different Malaxation Conditions (2022) doi | Read as context (not in the table) | Malaxation temperature (20, 25, 30 °C) and time varied; the text says the 30 °C samples were associated with bitterness and astringency in a multivariate analysis; however, Table A1 of the 2021 paper on the same samples shows the trees and ripeness of the fruit differed by condition, so it is not a comparison of temperature alone and no row was made; values in Fig. 1; read in full |
| Effect of Duration of Olive Storage on Chemical and Sensory Quality of Extra Virgin Olive Oils (2021) doi | Read as context (not in the table) | An observational study grouping 228 batches from 7 mills over 3 seasons by fruit storage days (Table 5: 2.16 within 24 h, 1.35 at 4–6 days, and so on); not a comparison changing storage alone for the same fruit, so no row was made; read in full |
| Does the Harvest Type Affect Olive Health? Influence of the Harvesting System and Storage Time on the Chemical, Volatile and Sensory Qualities of Extra Virgin Olive Oils (2023) doi | Read as context (not in the table) | Harvest method and fruit storage (5 °C and 18 °C) compared; the 1–9 scale in the methods is described in a quality direction (worst to best), so reading it as ordinary bitterness intensity needs caution; rated once 3 months after milling, with no test for bitterness, so no row was made; read in full |
| Extra Virgin Olive Oil from Destoned Fruits to Improve the Quality of the Oil and Environmental Sustainability (2022) doi | Read as context (not in the table) | A review of destoning; the primary papers it cites were not checked, so it is not counted as an independent study; read in full |
| Evolution of Flavors in Extra Virgin Olive Oil Shelf-Life (2021) doi | Read as context (not in the table) | A review of storage and flavour; not counted as an independent study; read in full |
| Optimizing the Malaxation Conditions to Produce an Arbequina EVOO with High Content of Bioactive Compounds (2021) doi | Read as context (not in the table) | Chemical analysis of the same samples as Olmo-Cunillera et al. 2022, with no human bitterness rating; Table A1 was used to check how fruit was allocated; read in full |
| Influence of the Washing Process and the Time of Fruit Harvesting Throughout the Day on Quality and Chemosensory Profile of Organic Extra Virgin Olive Oils (2022) doi | Excluded | A comparison of fruit washing, outside the scope of this question (extraction, filtration, fruit holding before milling, oil storage); no test of the bitterness comparison is shown either (the reason for exclusion is scope, not the lack of a test) |
| Check-All-That-Apply (CATA) Test to Investigate the Consumers’ Perception of Olive Oil Sensory Properties: Effect of Storage Time and Packaging Material (2021) doi | Excluded | Consumer CATA (selecting applicable terms) and liking, with no result usable for comparing bitterness intensity |
| Oxygen as a Possible Technological Adjuvant during the Crushing or the Malaxation Steps, or Both, for the Modulation of the Characteristics of Extra Virgin Olive Oil (2023) doi | Excluded | Chemical analysis of Picual oil under different oxygen conditions; the methods and result tables contain no human bitterness comparison |
| Olive Oil Produced from Olives Stored under CO2 Atmosphere: Volatile and Physicochemical Characterization (2022) doi | Excluded | People rated the bitterness of the fruit, not of the oil |
| Unconventional Extraction and Storage Strategies in Order to Enhance the Shelf Life of Virgin Olive Oil (2024) doi | Excluded | "Bitterness intensity" is an absorbance index at 225 nm, not a human rating |
| From Composition to Shelf Life: Oxidative Deterioration Trajectories of Monovarietal Extra Virgin Olive Oils (2026) doi | Excluded | Bitterness only at the start of storage, with no comparison after storage |
| Filtration Scheduling: Quality Changes in Freshly Produced Virgin Olive Oil (2020) doi | Excluded | The sensory assessment covers aroma (fruitiness and defects), with no bitterness result |
| Impact of Frozen Storage on Sensory, Physicochemical, and Volatile Compounds Parameters of Different Extra Virgin Olive Oils (2024) doi | Excluded | The sensory method and attributes cover aroma and defects, with no bitterness result by storage condition |
| Tracking Sensory Characteristics of Virgin Olive Oils During Storage: Interpretation of Their Changes from a Multiparametric Perspective (2020) doi | Excluded | Sensory reports during storage cover defects and fruitiness, with no bitterness time series |
| Preliminary Evaluation of the Nutraceutical Properties in Monovarietal Extra-Virgin Olive Oils and Monitoring Their Stability During Storage (2025) doi | Excluded | Table 1 has initial sensory values, but bitterness results by storage time point are not published |
| Influence of Extraction Techniques on Physical-chemical Characteristics and Volatile Compounds of Extra Virgin Olive Oil (2014) doi | Excluded | Compares extraction methods (press, decanter), but only by chemical analysis and electronic nose, with no human bitterness comparison (checked in the J-STAGE PDF) |
| Quality Authentication of Percolated and Centrifuged Enzyme-Treated Virgin Oils Produced Processing Olives (1999) | Excluded | The methods describe 12 assessors rating a 1–5 profile that includes bitterness, but the published comparison is of overall scores and the like, with no bitterness result by group (checked in page images of the J-STAGE PDF; DOI not confirmed in the PDF) |
Read in the encyclopedia
- Which compounds set the bitterness of extra virgin olive oil? — a comparison of bitterness and compounds
- Extra virgin olive oil — the food in this question
- Olive oil phenolic compounds — the group of compounds credited with bitterness
- Does adding sugar or salt suppress bitterness? — a comparison page of the same kind
Source ledger
Each study's source can be reached from its section above. All of the lab's sources are listed in the source ledger.
How to cite this page
Aoki, M. (NIGAMI LAB) (2026). Does extraction or storage change olive oil bitterness?. https://nigamilab.com/en/topics/olive-oil-processing-bitterness/
Each claim card has a stable anchor (#clm-…). The dataset is CC BY 4.0; see the data page. Dataset DOI: 10.5281/zenodo.22739101