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Does adding an ingredient to a bitter sample such as quinine or amino acids lower the bitterness people perceive?
Sensory tests of adding amino acids, acids, polyphenols and other ingredients
To be clear from the start, this page is about studies that compared, for the same bitter sample, a condition with an ingredient added against a condition without it, and looked at how bitter people found the result. The bitter samples include solutions of quinine and amino acids as well as solutions of medicine ingredients and medicine formulations (tablets that disintegrate in the mouth, chewable tablets).
Studies that used medicine formulations as samples are included, but this page is not advice on how to take or mix medicines. The amounts in the tables are research conditions and are not to be read as amounts to add to a medicine or as a guide for dispensing or taking medicines.
Bitterness when a bitter medicine is mixed with food, drink or medication jellies is covered on the page Does mixing a bitter medicine with food or drink soften its bitterness?. This page is not about mixing into food but about adding ingredients such as amino acids, acids and polyphenols to the sample itself. Comparisons adding sugar or salt are on the page Does adding sugar or salt suppress bitterness?, and this page does not count sugar, salt, sweeteners or flavourings as ingredients.
So what do studies say that kept the amount of the bitter component the same, compared whether an ingredient was added to the same bitter sample, and had people rate bitterness? The tablet studies include comparisons between formulations in which the excipient was reduced by the amount of the added ingredient. This page lines up the included studies, by study and by condition, together with their conditions: the bitter sample, the ingredient and its amount, and who rated it on what scale.
To be honest at the outset, research of this kind leans towards reports from people looking for ways to suppress bitterness. Unpublished results are not known to us, so whether there is publication bias cannot be assessed. Also, of the eight studies checked in full text and tabulated, five are reports from the same laboratory and are not independent studies; grouped broadly by research group they form four. Even so, within the same study there are pairs where the published mean fell with the ingredient, pairs where it rose, pairs where it fell but no significant difference was shown, and pairs with no test result given. For this reason no summary of which ingredients lower bitterness is given; the published values and tests are shown by study and by condition.
Some studies show values only in figures, and in some the text and the figure disagree, so please check the test and the note in each row. Bitter samples, ingredients, scales and raters differ by study, so values are not compared across studies or turned into ratios. This page then separates what was established within one experiment, what differences between studies might explain, and what this comparison alone cannot separate.
On this page (9 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
What this page establishes
- This page lines up, by study and by condition, studies in which people rated bitterness intensity and compared the same bitter sample with and without an added ingredient. The bitter samples are solutions of quinine, amino acids and medicine ingredients, and medicine formulations; this time no study of a food could be adopted into the table (studies with foods as samples are listed, with reasons, in the table of what we looked at, as removal treatments or as conditions that could not be confirmed).
- The literature leans towards reports from people looking for ways to suppress bitterness, and five of the eight studies are reports from the same laboratory. Grouped broadly by research group they form four.
- Even so, the direction splits: in some pairs the published mean was higher with the ingredient (some amino acids, and chewable tablets with beta-cyclodextrin).
- Some pairs fell on average but showed no significant difference, and some have no test result given. Not showing a significant difference does not mean there is no difference.
- Where text and figure disagree, both are kept rather than rewritten to one. Studies that used medicine formulations as samples are included, but this page is not advice on how to take or mix medicines.
What the included studies allow us to say
- Among studies in which people rated bitterness intensity for the same bitter sample (solutions of quinine, amino acids or medicine ingredients, or medicine formulations) with and without an added ingredient, eight were checked in full text and tabulated, giving thirty-seven compared pairs. Five of the eight are reports from the same laboratory (Mukogawa Women's University, with the same corresponding author) and are not independent studies. Grouped broadly by research group in the ledger they form four groups, which also differ in ingredients, bitter samples and conditions.
- Studies of this kind are mostly reports from people looking for ways to suppress bitterness, and the included studies, too, are mostly experiments aimed at finding suppressing ingredients. Unpublished results are not known to us, so whether there is publication bias cannot be assessed. Even so, within the same study there are pairs where the published mean fell, pairs where it rose, pairs where it fell but no significant difference was shown, and pairs with no test result given.
- There are also pairs where the published mean was higher with the ingredient. With 0.15% (w/v) L-lysine the value was higher in all of the isoleucine, phenylalanine and quinine solutions (approximate, from the figure), and with 0.15% (w/v) L-glutamic acid it was higher in the quinine solution; none has a mark in the figure and no test result is given. In dexamethasone chewable tablets, the tablet with 3.00% beta-cyclodextrin and the tablet with both it and GABA were higher than the tablet without, both right after spitting out and at 2 min (no test result published). [rows: Ogawa 2004 Isoleucine solution + 0.15% (w/v) L-lysine vs isoleucine solution alone; Ogawa 2004 Phenylalanine solution + 0.15% (w/v) L-lysine vs phenylalanine solution alone; Ogawa 2004 Quinine solution + 0.15% (w/v) L-lysine vs quinine solution alone; Ogawa 2004 Quinine solution + 0.15% (w/v) L-glutamic acid vs quinine solution alone; Dadkhah 2025 Tablet with 3.00% beta-cyclodextrin vs tablet without; Dadkhah 2025 Tablet with 3.00% GABA + 3.00% beta-cyclodextrin vs tablet without]
- There are also pairs where the published mean fell but no significant difference was shown. The five formulations of olopatadine hydrochloride orally disintegrating tablets with citric acid all had lower means than the tablet without, but the pairwise p values did not meet the threshold set by the authors (p<0.01). For the L-valine solution with 100 mM L-ornithine, the text says no significant difference was obtained. That no significant difference was shown does not mean there is no difference. [rows: Sotoyama 2017 Tablet with 0.1% citric acid vs tablet without; Sotoyama 2017 Tablet with 1% citric acid vs tablet without; Sotoyama 2017 Tablet with 2.5% citric acid vs tablet without; Sotoyama 2017 Tablet with 5% citric acid vs tablet without; Sotoyama 2017 Tablet with 10% citric acid vs tablet without; Tokuyama 2006 Valine solution + 100 mM L-ornithine vs valine solution alone]
- Bitter samples, ingredients, amounts, scales and raters differ between studies, and even the same ingredient gives different results with different samples (0.15% (w/v) L-arginine lowered bitterness significantly in the isoleucine and quinine solutions, while for the phenylalanine solution no individual test result is shown). So no summary of which ingredients lower bitterness is given; published values and tests are listed by study and by condition. This page deals only with bitterness ratings. It includes studies that used medicine formulations as samples, but it is not advice on how to take or mix medicines. [rows: Ogawa 2004 Isoleucine solution + 0.15% (w/v) L-arginine vs isoleucine solution alone; Ogawa 2004 Quinine solution + 0.15% (w/v) L-arginine vs quinine solution alone; Ogawa 2004 Phenylalanine solution + 0.15% (w/v) L-arginine vs phenylalanine solution alone]
- Some material was not given rows and was held or left out of scope. Even within included studies, some pairs where text and figure disagree so that the direction could not be settled (the higher tannic acid concentration; the leucine and valine solutions with L-arginine), and concentrations given differently in the abstract, methods and figure, are not given rows. The disagreement over the test result for L-glutamic acid is kept in a row with a note. The pairs in which BCAA solutions were mixed with tartaric acid solutions are on hold, because the mixing ratio and final concentrations are not stated and it cannot be confirmed that the amount of the bitter component was the same. Studies that compare whether a sample is mixed into a gel (such as agar), with the gel as the additive, are close to medication jellies and are left out of scope. Studies that used sweeteners as the bitter sample, treatments that remove the bitter component, comparisons between different formulations, studies that compared the physical coating itself (with or without coating, amount of coating) as the factor, taste-sensor-only studies, and studies that measured only acceptability rather than bitterness were also left out. Abstract-only material is on hold because the pairs of bitterness values cannot be confirmed.
Bitterness ratings at a glance
Only the results of people's bitterness ratings are pulled out here. Bitter sample, scale and aggregation differ by study, so values are not compared across studies. In each label, the condition with the ingredient comes before "vs" and the condition without it after, and the value columns follow the same order. The amount of the ingredient is given as a research condition in each row's label and condition. The "direction" column shows which was more bitter as "… more bitter". The direction shows only which published value is larger. Rows where the direction differs between two time points are shown as "depends on the combination". Whether a difference is significant is in the test line of the "direction / test" column. Even in rows with no significant difference, the direction column shows which value is larger. Rows where a test method is described but no result for the two conditions shown is given are marked "result for this comparison not reported", and are not called not significant. Rows whose values exist only in a figure say in the value column that they are approximate readings from the figure. For tablet studies that rated two time points, the values for both time points are given in the row for the same pair. Clicking a study name jumps to its detailed table under "Conditions and results, study by study". Test conditions, significance levels and disagreements between text and figures are given under each row there.
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 | With the added ingredient | Without it | Direction / test |
|---|---|---|---|---|---|
| Nakamura 2002 (phosphatidic and tannic acids) | Quinine + 0.1% (w/v) phosphatidic acid vs quinine alone 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with 0.1% (w/v) of the commercial bitterness suppressant phosphatidic acid (BMI-40) added; B is the same quinine solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 11 people; values approximate, read from Fig. 1B | about 0.9 (approximate, from the figure) | about 1.6 (approximate, from the figure) | Without it more bitter No test reported |
| Nakamura 2002 (phosphatidic and tannic acids) | Quinine + 1.0% (w/v) phosphatidic acid vs quinine alone 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with 1.0% (w/v) phosphatidic acid (BMI-40) added; B is the same quinine solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 11 people; values approximate, read from Fig. 1B | about 0.2 (approximate, from the figure) | about 1.6 (approximate, from the figure) | Without it more bitter No test reported |
| Nakamura 2002 (phosphatidic and tannic acids) | Quinine + 0.05% (w/v) tannic acid vs quinine alone 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with 0.05% (w/v) tannic acid added; B is the same quinine solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 11 people; values approximate, read from Fig. 1B | about 0.7 (approximate, from the figure) | about 1.6 (approximate, from the figure) | Without it more bitter No test reported |
| Ogawa 2004 | Isoleucine solution + 1.0% (w/v) phosphatidic acid vs isoleucine solution alone 100 mM L-isoleucine solution with 1.0% (w/v) phosphatidic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | 1.15±0.23 (text) | 1.68±0.14 (text) | Without it more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Phenylalanine solution + 1.0% (w/v) phosphatidic acid vs phenylalanine solution alone 100 mM L-phenylalanine solution with 1.0% (w/v) phosphatidic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | 2.08±0.25 (text) | 2.62±0.20 (text) | Without it more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Phenylalanine solution + 0.005% (w/v) tannic acid vs phenylalanine solution alone 100 mM L-phenylalanine solution with 0.005% (w/v) tannic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | 1.72±0.27 (text) | 2.62±0.20 (text) | Without it more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Isoleucine solution + 0.15% (w/v) L-arginine vs isoleucine solution alone 100 mM L-isoleucine solution with 0.15% (w/v) L-arginine added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | 0.50±0.25 (text) | 1.68±0.43 (text) | Without it more bitter Tested, significant |
| Ogawa 2004 | Quinine solution + 0.15% (w/v) L-arginine vs quinine solution alone 0.1 mM quinine hydrochloride solution with 0.15% (w/v) L-arginine added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | 0.88±0.37 (text) | 2.03±0.20 (text) | Without it more bitter Tested, significant |
| Ogawa 2004 | Phenylalanine solution + 0.15% (w/v) L-arginine vs phenylalanine solution alone 100 mM L-phenylalanine solution with 0.15% (w/v) L-arginine added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | 2.14±0.20 (text) | 2.62±0.37 (text) | Without it more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Isoleucine solution + 0.15% (w/v) L-lysine vs isoleucine solution alone 100 mM L-isoleucine solution with 0.15% (w/v) L-lysine added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | about 2.55 (approximate, from the figure) | about 1.7 (approximate, from the figure) | With the added ingredient more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Phenylalanine solution + 0.15% (w/v) L-lysine vs phenylalanine solution alone 100 mM L-phenylalanine solution with 0.15% (w/v) L-lysine added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | about 3.05 (approximate, from the figure) | about 2.65 (approximate, from the figure) | With the added ingredient more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Quinine solution + 0.15% (w/v) L-lysine vs quinine solution alone 0.1 mM quinine hydrochloride solution with 0.15% (w/v) L-lysine added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | about 2.65 (approximate, from the figure) | about 2.05 (approximate, from the figure) | With the added ingredient more bitter Test method described; result for this comparison not reported |
| Ogawa 2004 | Quinine solution + 0.15% (w/v) L-glutamic acid vs quinine solution alone 0.1 mM quinine hydrochloride solution with 0.15% (w/v) L-glutamic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | about 2.75 (approximate, from the figure) | about 2.05 (approximate, from the figure) | With the added ingredient more bitter Test method described; result for this comparison not reported |
| Tokuyama 2006 | Isoleucine solution + 100 mM L-ornithine vs isoleucine solution alone 100 mM L-isoleucine solution with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | 1.01 (text) | 1.76 (text) | Without it more bitter Tested, significant |
| Tokuyama 2006 | Leucine solution + 100 mM L-ornithine vs leucine solution alone 100 mM L-leucine solution with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | about 1.05 (approximate, from the figure) | about 1.8 (approximate, from the figure) | Without it more bitter Tested, significant |
| Tokuyama 2006 | Valine solution + 100 mM L-ornithine vs valine solution alone 100 mM L-valine solution with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | 0.58 (text) | 1.20 (text) | Without it more bitter Tested, not significant |
| Tokuyama 2006 | Mixed BCAA solution + 100 mM L-ornithine vs mixed BCAA solution alone mixed BCAA solution (28.1 mM L-isoleucine, 12.1 mM L-leucine, 60.7 mM L-valine) with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 trained people (mean±SE) | 0.17 (text) | 1.33 (text) | Without it more bitter Tested, significant |
| Tokuyama 2006 | Isoleucine solution + 100 mM L-arginine vs isoleucine solution alone 100 mM L-isoleucine solution with 100 mM L-arginine added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | about 1.1 (approximate, from the figure) | 1.76 (text) | Without it more bitter Test method described; result for this comparison not reported |
| Tokuyama 2006 | Mixed BCAA solution + 100 mM L-arginine vs mixed BCAA solution alone mixed BCAA solution (28.1 mM L-isoleucine, 12.1 mM L-leucine, 60.7 mM L-valine) with 100 mM L-arginine added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 trained people (mean±SE) | 0.50 (text) | 1.33 (text) | Without it more bitter Tested, significant |
| Shiraishi 2017 | Diphenhydramine solution + 1.0 mM chlorogenic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM chlorogenic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); values approximate, read from Fig. 3 (the source gives mean±SD) | about 1.2 (approximate, from the figure) | about 2.3 (approximate, from the figure) | Without it more bitter Tested, significant |
| Shiraishi 2017 | Diphenhydramine solution + 1.0 mM quinic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM quinic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); values approximate, read from Fig. 3 (the source gives mean±SD) | about 0.7 (approximate, from the figure) | about 2.3 (approximate, from the figure) | Without it more bitter Tested, significant |
| Shiraishi 2017 | Diphenhydramine solution + 1.0 mM caffeic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM caffeic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); values approximate, read from Fig. 3 (the source gives mean±SD) | about 1.2 (approximate, from the figure) | about 2.3 (approximate, from the figure) | Without it more bitter Tested, significant |
| Okuno 2020 | Diphenhydramine solution + 1.0 mM Glu-Glu (an umami dipeptide) vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM Glu-Glu (an umami dipeptide) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | about 0.8 (approximate, from the figure) | about 1.9 (approximate, from the figure) | Without it more bitter Tested, significant |
| Okuno 2020 | Diphenhydramine solution + 1.0 mM Asp-Asp (an umami dipeptide) vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM Asp-Asp (an umami dipeptide) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | about 0.95 (approximate, from the figure) | about 1.9 (approximate, from the figure) | Without it more bitter Tested, significant |
| Okuno 2020 | Diphenhydramine solution + 1.0 mM Gly-Gly (a dipeptide) vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM Gly-Gly (a dipeptide) added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | about 1.6 (approximate, from the figure) | about 1.9 (approximate, from the figure) | Without it more bitter Test method described; result for this comparison not reported |
| Okuno 2020 | Diphenhydramine solution + 1.0 mM L-glutamic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM L-glutamic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | about 1.15 (approximate, from the figure) | about 1.9 (approximate, from the figure) | Without it more bitter Test results conflict between text and figure |
| Okuno 2020 | Diphenhydramine solution + 1.0 mM L-aspartic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM L-aspartic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | about 1.0 (approximate, from the figure) | about 1.9 (approximate, from the figure) | Without it more bitter Tested, significant |
| Okuno 2020 | Diphenhydramine solution + 1.0 mM glycine vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM glycine added; B is the same solution alone; 2 mL held in the mouth for 5 s | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | about 1.6 (approximate, from the figure) | about 1.9 (approximate, from the figure) | Without it more bitter Test method described; result for this comparison not reported |
| Sotoyama 2017 | Tablet with 0.1% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 0.25 mg (0.1%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 198.29 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | during disintegration about 42, right after spitting out about 28 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | Without it more bitter Tested, not significant |
| Sotoyama 2017 | Tablet with 1% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 2.50 mg (1%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 196.04 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | during disintegration about 30, right after spitting out about 35 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | Without it more bitter Tested, not significant |
| Sotoyama 2017 | Tablet with 2.5% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 6.25 mg (2.5%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 192.29 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | during disintegration about 22, right after spitting out about 17 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | Without it more bitter Tested, not significant |
| Sotoyama 2017 | Tablet with 5% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 12.50 mg (5%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 186.04 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | during disintegration about 27, right after spitting out about 26 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | Without it more bitter Tested, not significant |
| Sotoyama 2017 | Tablet with 10% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 25.00 mg (10%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 173.54 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | during disintegration about 20, right after spitting out about 24 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | Without it more bitter Tested, not significant |
| Dadkhah 2025 | Tablet with 3.00% GABA vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. 3D-printed dexamethasone chewable tablets (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (Table 2; the raw material is a 70% sorbitol solution) and others in the same amounts in every tablet) with 3.00% GABA (gamma-aminobutyric acid); B is the tablet with neither added GABA nor beta-cyclodextrin. Crushed and held on the tongue for 30 s, rated right after spitting out and at 2 min | bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; mean of 6 adults (6 right after spitting out, 5 at 2 min) | right after spitting out 20.40, at 2 min 13.89 (Table 4) | right after spitting out 30.08, at 2 min 12.26 (Table 4) | Depends on the combination No test reported |
| Dadkhah 2025 | Tablet with 3.00% beta-cyclodextrin vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. 3D-printed dexamethasone chewable tablets (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (Table 2; the raw material is a 70% sorbitol solution) and others in the same amounts in every tablet) with 3.00% beta-cyclodextrin; B is the tablet with neither added GABA nor beta-cyclodextrin. Crushed and held on the tongue for 30 s, rated right after spitting out and at 2 min | bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; mean of 6 adults (6 right after spitting out, 5 at 2 min) | right after spitting out 41.48, at 2 min 28.54 (Table 4) | right after spitting out 30.08, at 2 min 12.26 (Table 4) | With the added ingredient more bitter No test reported |
| Dadkhah 2025 | Tablet with 3.00% GABA + 3.00% beta-cyclodextrin vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. 3D-printed dexamethasone chewable tablets (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (Table 2; the raw material is a 70% sorbitol solution) and others in the same amounts in every tablet) with both 3.00% GABA and 3.00% beta-cyclodextrin; B is the tablet with neither added GABA nor beta-cyclodextrin. Crushed and held on the tongue for 30 s, rated right after spitting out and at 2 min | bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; mean of 6 adults (6 right after spitting out, 5 at 2 min) | right after spitting out 43.49, at 2 min 23.75 (Table 4) | right after spitting out 30.08, at 2 min 12.26 (Table 4) | With the added ingredient more bitter No test reported |
| Sterneder 2024 | Quinine solution + 100 ppm DMDHE vs quinine solution alone Quinine 10 ppm in water with 100 ppm of 4′-demethyl-3,9-dihydroeucomin (DMDHE), a compound isolated from the resin of dragon's blood palm (Daemonorops draco) and later synthesised; B is the same quinine solution alone. Paired comparison of 2 samples, rated with a nose clip | bitterness rating 0–100 (0 = not bitter, 100 = very bitter; the methods section says 0–10, while the results and figure legends say 0–100); mean of a trained panel of 22 (the statistics section says data are mean±SEM unless stated otherwise) | 53.8±3.6 (text) | 64.1±3.7 (text) | Without it more bitter Tested, significant |
Conditions and results, study by study
For each study, the bitter sample and ingredient conditions, how samples were served and who rated them are set out next to the measured results. Each row is one "study × measured result", and a different ingredient or amount within the same study is a separate row. Under each row are its location in the paper and whether the row can be used for the comparison "whether, for the same bitter sample, adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it", with the reason. No cell is left blank: "not given" (not stated in the paper), "not read" and "not applicable" are kept apart. Where a study's text and figure disagree, the disagreement is kept. Results from taste sensors and other instruments are kept apart from human ratings and are not rows.
Nakamura 2002 (phosphatidic and tannic acids) sensory only
The effect of various substances on the suppression of the bitterness of quinine-human gustatory sensation, binding, and taste sensor studies. Chemical & Pharmaceutical Bulletin — doi:10.1248/cpb.50.1589
- How deeply checked
- Checked in full text — Full 5-page PDF via J-STAGE (Methods; Results and discussion; Fig. 1B); values in Fig. 1B were read by eye from an enlarged page image (the paper has no table of values). The sucrose and NaCl pairs of the same paper are held by the sugar-and-salt page as study nakamura2002; this row is the study entry for the phosphatidic acid and tannic acid pairs Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with phosphatidic acid (the commercial bitterness suppressant BMI-40) at 0.001, 0.01, 0.1 and 1.0% (w/v) or tannic acid at 0.005, 0.015, 0.05 and 0.15% (w/v) added (concentrations as listed in the methods)
- Processing and cooking
- Not applicable (simply added to solutions)
- How it was served or eaten
- 5 mL held in the mouth for 15 s; gargling and at least 20 min between samples
- Who rated, on what scale
- 11 people, who first learned quinine hydrochloride standards of 0.01, 0.03, 0.1, 0.3 and 1 mM as bitterness scores 0–4 and then scored the samples; figures show mean±SEM; no test method is given for the phosphatidic acid and tannic acid pairs
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Quinine + 0.1% (w/v) phosphatidic acid vs quinine alone 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with 0.1% (w/v) of the commercial bitterness suppressant phosphatidic acid (BMI-40) added; B is the same quinine solution alone; 5 mL held in the mouth for 15 s | about 0.9 (approximate, from the figure) | about 1.6 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 11 people; values approximate, read from Fig. 1B | Without it more bitter No test reported |
| Direction shows which approximate value read from the figure is larger. The source only shows mean±SEM in the figure; no test method or result is given for this pair (the text says phosphatidic acid lowered bitterness markedly). Readings from the figure have a margin of about ±0.1–0.2. Fig. 1B also has phosphatidic acid points not listed in the methods (at about 0.25 and 0.5%) Where: Methods (gustatory sensation test); Results and discussion; Fig. 1B For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same quinine solution, differing only in whether the ingredient was added; 11 people rated on the same standard scale. No test result, and values are read from the figure | |||||
| Bitterness intensity (sensory) | Quinine + 1.0% (w/v) phosphatidic acid vs quinine alone 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with 1.0% (w/v) phosphatidic acid (BMI-40) added; B is the same quinine solution alone; 5 mL held in the mouth for 15 s | about 0.2 (approximate, from the figure) | about 1.6 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 11 people; values approximate, read from Fig. 1B | Without it more bitter No test reported |
| Direction shows which approximate value read from the figure is larger. The source only shows mean±SEM in the figure; no test method or result is given for this pair (the text says it fell to about 10% of the control, and the abstract gives the suppression as 81.7%). Readings from the figure have a margin of about ±0.1–0.2. Fig. 1B also has phosphatidic acid points not listed in the methods (at about 0.25 and 0.5%). The suppression percentages in the abstract and Fig. 2B are based on converting the bitterness scores to equivalent quinine concentrations, and are not ratios of the 0–4 scores shown here Where: Methods (gustatory sensation test); Results and discussion; Fig. 1B For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same quinine solution, differing only in whether the ingredient was added; 11 people rated on the same standard scale. No test result, and values are read from the figure | |||||
| Bitterness intensity (sensory) | Quinine + 0.05% (w/v) tannic acid vs quinine alone 0.1 mM quinine hydrochloride solution (prepared in 10 mM KCl) with 0.05% (w/v) tannic acid added; B is the same quinine solution alone; 5 mL held in the mouth for 15 s | about 0.7 (approximate, from the figure) | about 1.6 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 11 people; values approximate, read from Fig. 1B | Without it more bitter No test reported |
| Direction shows which approximate value read from the figure is larger. The source only shows mean±SEM in the figure; no test method or result is given for this pair (the text says bitterness fell with concentration up to 0.05%, and the abstract gives the suppression as 61.0%). Readings from the figure have a margin of about ±0.1–0.2. Fig. 1B also has phosphatidic acid points not listed in the methods (at about 0.25 and 0.5%). The suppression percentage in the abstract is based on converting the bitterness scores to equivalent quinine concentrations, and is not a ratio of the 0–4 scores shown here. For 0.15% tannic acid the text says 1.5, "significantly higher than control", but in the figure it is about 1.5, below the control of about 1.6; text and figure disagree, so it is not given a row Where: Methods (gustatory sensation test); Results and discussion; Fig. 1B For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same quinine solution, differing only in whether the ingredient was added; 11 people rated on the same standard scale. No test result, and values are read from the figure | |||||
Ogawa 2004 sensory only
The Combination Effect of L-Arginine and NaCl on Bitterness Suppression of Amino Acid Solutions. Chemical & Pharmaceutical Bulletin 52(2):172-177 — doi:10.1248/cpb.52.172
- How deeply checked
- Checked in full text — Full text via the J-STAGE PDF (Methods; Results and discussion; Figs. 1C and 2); Figs. 1 and 2 were checked as page images (approximate points and marks) Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- 100 mM L-isoleucine, 100 mM L-phenylalanine and 0.1 mM quinine hydrochloride solutions with phosphatidic acid at 0.001–1.0% (w/v), tannic acid at 0.005–0.15% (w/v), and L-arginine, L-lysine, L-histidine, L-aspartic acid or L-glutamic acid at 0.05, 0.10 and 0.15% (w/v) added; there are also sucrose, aspartame and NaCl pairs, which are not in this table
- Processing and cooking
- Not applicable (simply added to solutions)
- How it was served or eaten
- 5 mL held in the mouth for 15 s; gargling and at least 20 min between samples
- Who rated, on what scale
- 6 informed volunteers, who first learned quinine hydrochloride standards of 0.01, 0.03, 0.10, 0.30 and 1.00 mM as bitterness scores 0–4; figures show mean±SEM; one-way analysis of variance followed by two-sample t-tests
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Isoleucine solution + 1.0% (w/v) phosphatidic acid vs isoleucine solution alone 100 mM L-isoleucine solution with 1.0% (w/v) phosphatidic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | 1.15±0.23 (text) | 1.68±0.14 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | Without it more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which published value (text) is larger. Fig. 1C has no individual marks, and no test result is given for this pair. The text says phosphatidic acid lowered isoleucine by about 30% and phenylalanine by about 20%. The SEM of the no-addition value differs between the phosphatidic acid paragraph (±0.14, ±0.20) and the L-arginine paragraph (±0.43, ±0.37); whether they are the same measurement is not stated. Each paragraph's values are given as published Where: Methods; Results and discussion (phosphatidic acid and tannic acid paragraphs); Fig. 1C For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Phenylalanine solution + 1.0% (w/v) phosphatidic acid vs phenylalanine solution alone 100 mM L-phenylalanine solution with 1.0% (w/v) phosphatidic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | 2.08±0.25 (text) | 2.62±0.20 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | Without it more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which published value (text) is larger. Fig. 1C has no individual marks, and no test result is given for this pair. The text says phosphatidic acid lowered isoleucine by about 30% and phenylalanine by about 20%. The SEM of the no-addition value differs between the phosphatidic acid paragraph (±0.14, ±0.20) and the L-arginine paragraph (±0.43, ±0.37); whether they are the same measurement is not stated. Each paragraph's values are given as published Where: Methods; Results and discussion (phosphatidic acid and tannic acid paragraphs); Fig. 1C For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Phenylalanine solution + 0.005% (w/v) tannic acid vs phenylalanine solution alone 100 mM L-phenylalanine solution with 0.005% (w/v) tannic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | 1.72±0.27 (text) | 2.62±0.20 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | Without it more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which published value (text) is larger. Fig. 1C has no individual marks, and no test result is given for this pair. The text says that above 0.15% (w/v) tannic acid the bitterness of the phenylalanine solution rose so much that the sensory test could not be carried out (no value at that concentration) Where: Results and discussion (tannic acid paragraph); Fig. 1C For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Isoleucine solution + 0.15% (w/v) L-arginine vs isoleucine solution alone 100 mM L-isoleucine solution with 0.15% (w/v) L-arginine added; B is the same solution alone; 5 mL held in the mouth for 15 s | 0.50±0.25 (text) | 1.68±0.43 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | Without it more bitter Tested, significant |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which published value (text) is larger. The text says it was significantly lower, and the 0.15% point in Fig. 2C has *. The SEM of the no-addition value differs between the phosphatidic acid paragraph (±0.14, ±0.20) and the L-arginine paragraph (±0.43, ±0.37); whether they are the same measurement is not stated. Each paragraph's values are given as published Where: Results and discussion (L-arginine paragraph); Fig. 2C For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel | |||||
| Bitterness intensity (sensory) | Quinine solution + 0.15% (w/v) L-arginine vs quinine solution alone 0.1 mM quinine hydrochloride solution with 0.15% (w/v) L-arginine added; B is the same solution alone; 5 mL held in the mouth for 15 s | 0.88±0.37 (text) | 2.03±0.20 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | Without it more bitter Tested, significant |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which published value (text) is larger. The text says it was significantly lower, and the 0.15% point in Fig. 2C has *. The point in Fig. 2C looks slightly higher than the text value (about 1.0), while the starting point in Fig. 2D is close to the text value Where: Results and discussion (L-arginine paragraph); Figs. 2C and 2D For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel | |||||
| Bitterness intensity (sensory) | Phenylalanine solution + 0.15% (w/v) L-arginine vs phenylalanine solution alone 100 mM L-phenylalanine solution with 0.15% (w/v) L-arginine added; B is the same solution alone; 5 mL held in the mouth for 15 s | 2.14±0.20 (text) | 2.62±0.37 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | Without it more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which published value (text) is larger. The text says it was "only slightly reduced", and the 0.15% point in Fig. 2C has no mark. No test result is given for this pair (it is not described as not significant). The SEM of the no-addition value differs between the phosphatidic acid paragraph (±0.14, ±0.20) and the L-arginine paragraph (±0.43, ±0.37); whether they are the same measurement is not stated. Each paragraph's values are given as published Where: Results and discussion (L-arginine paragraph); Fig. 2C For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Isoleucine solution + 0.15% (w/v) L-lysine vs isoleucine solution alone 100 mM L-isoleucine solution with 0.15% (w/v) L-lysine added; B is the same solution alone; 5 mL held in the mouth for 15 s | about 2.55 (approximate, from the figure) | about 1.7 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | With the added ingredient more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which approximate value read from the figure is larger. Fig. 2A has no marks, and no test result is given for this pair. The methods give L-lysine and L-glutamic acid at 0.05, 0.10 and 0.15% (w/v); the axes of Figs. 2A and 2B have no numbers, so the rightmost point is read as 0.15%. The text says L-aspartic acid and L-histidine did not mask any of the solutions either (data not shown). Readings from the figure have a margin of about ±0.1–0.2 Where: Methods (sample concentrations; statistics); Results and discussion; Fig. 2A For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Phenylalanine solution + 0.15% (w/v) L-lysine vs phenylalanine solution alone 100 mM L-phenylalanine solution with 0.15% (w/v) L-lysine added; B is the same solution alone; 5 mL held in the mouth for 15 s | about 3.05 (approximate, from the figure) | about 2.65 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | With the added ingredient more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which approximate value read from the figure is larger. Fig. 2A has no marks, and no test result is given for this pair. The methods give L-lysine and L-glutamic acid at 0.05, 0.10 and 0.15% (w/v); the axes of Figs. 2A and 2B have no numbers, so the rightmost point is read as 0.15%. The text says L-aspartic acid and L-histidine did not mask any of the solutions either (data not shown). Readings from the figure have a margin of about ±0.1–0.2 Where: Methods (sample concentrations; statistics); Results and discussion; Fig. 2A For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Quinine solution + 0.15% (w/v) L-lysine vs quinine solution alone 0.1 mM quinine hydrochloride solution with 0.15% (w/v) L-lysine added; B is the same solution alone; 5 mL held in the mouth for 15 s | about 2.65 (approximate, from the figure) | about 2.05 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | With the added ingredient more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which approximate value read from the figure is larger. Fig. 2A has no marks, and no test result is given for this pair. The methods give L-lysine and L-glutamic acid at 0.05, 0.10 and 0.15% (w/v); the axes of Figs. 2A and 2B have no numbers, so the rightmost point is read as 0.15%. The text says L-aspartic acid and L-histidine did not mask any of the solutions either (data not shown). Readings from the figure have a margin of about ±0.1–0.2 Where: Methods (sample concentrations; statistics); Results and discussion; Fig. 2A For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
| Bitterness intensity (sensory) | Quinine solution + 0.15% (w/v) L-glutamic acid vs quinine solution alone 0.1 mM quinine hydrochloride solution with 0.15% (w/v) L-glutamic acid added; B is the same solution alone; 5 mL held in the mouth for 15 s | about 2.75 (approximate, from the figure) | about 2.05 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 people | With the added ingredient more bitter Test method described; result for this comparison not reported |
| One-way analysis of variance followed by two-sample t-tests (* p<0.05, ** p<0.01; marks in the figures are against no addition). Direction shows which approximate value read from the figure is larger. Fig. 2B has no marks, and no test result is given for this pair. The methods give L-lysine and L-glutamic acid at 0.05, 0.10 and 0.15% (w/v); the axes of Figs. 2A and 2B have no numbers, so the rightmost point is read as 0.15%. The text says L-aspartic acid and L-histidine did not mask any of the solutions either (data not shown). Readings from the figure have a margin of about ±0.1–0.2. In the same figure the phenylalanine solution is slightly higher with the addition (about 2.75 vs about 2.6) and the isoleucine solution slightly lower (about 1.55 vs about 1.7); neither has a mark and the differences are small, so they are not given rows Where: Methods (sample concentrations; statistics); Results and discussion; Fig. 2B For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same amino acid (or quinine) solution, differing only in whether the ingredient was added; rated by 6 people, a small panel; no test result | |||||
Tokuyama 2006 sensory only
Bitterness Suppression of BCAA Solutions by L-Ornithine. Chemical & Pharmaceutical Bulletin 54(9):1288-1292 — doi:10.1248/cpb.54.1288
- How deeply checked
- Checked in full text — Full text via the J-STAGE PDF (Methods; Results and discussion; Figs. 1 and 2); Figs. 1 and 2 were checked as page images. Taste-sensor results are kept apart from human ratings and not given rows Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- 100 mM solutions of each of L-isoleucine, L-leucine and L-valine, and a mixed BCAA solution (28.1 mM L-isoleucine, 12.1 mM L-leucine, 60.7 mM L-valine), with L-ornithine (monohydrochloride) or L-arginine added at 1, 10 and 100 mM
- Processing and cooking
- Not applicable (simply added to solutions)
- How it was served or eaten
- 2 mL held in the mouth for 5 s; gargling and an interval between samples
- Who rated, on what scale
- 6–8 trained people (8 for single solutions, 6 for the mixed solution); bitterness score 0–4 matched to quinine standards; figures show mean±SE; Mann–Whitney U test
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Isoleucine solution + 100 mM L-ornithine vs isoleucine solution alone 100 mM L-isoleucine solution with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | 1.01 (text) | 1.76 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | Without it more bitter Tested, significant |
| Mann–Whitney U test (* p<0.05, ** p<0.01 in the figures, against no addition). Direction shows which published value (text) is larger. The 100 mM point in Fig. 1 has *. The text gives 1.64 and 1.51 at 1 and 10 mM Where: Results and discussion; Fig. 1 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same BCAA solution, differing only in whether L-ornithine (or L-arginine) was added; rated by a small trained panel | |||||
| Bitterness intensity (sensory) | Leucine solution + 100 mM L-ornithine vs leucine solution alone 100 mM L-leucine solution with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.05 (approximate, from the figure) | about 1.8 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | Without it more bitter Tested, significant |
| Mann–Whitney U test (* p<0.05, ** p<0.01 in the figures, against no addition). Direction shows which approximate value read from the figure is larger. The 100 mM point in Fig. 1 has *. Readings from the figure have a margin of about ±0.1 Where: Results and discussion; Fig. 1 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same BCAA solution, differing only in whether L-ornithine (or L-arginine) was added; rated by a small trained panel | |||||
| Bitterness intensity (sensory) | Valine solution + 100 mM L-ornithine vs valine solution alone 100 mM L-valine solution with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | 0.58 (text) | 1.20 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | Without it more bitter Tested, not significant |
| Mann–Whitney U test (* p<0.05, ** p<0.01 in the figures, against no addition). Direction shows which published value (text) is larger. The text says no statistically significant difference was obtained for this pair (which does not mean there is no difference). The authors suggest this may be because the score of the valine solution alone was low, and say that in a pilot test a 300 mM valine solution was lowered (details not shown) Where: Results and discussion; Fig. 1 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same BCAA solution, differing only in whether L-ornithine (or L-arginine) was added; rated by a small trained panel | |||||
| Bitterness intensity (sensory) | Mixed BCAA solution + 100 mM L-ornithine vs mixed BCAA solution alone mixed BCAA solution (28.1 mM L-isoleucine, 12.1 mM L-leucine, 60.7 mM L-valine) with 100 mM L-ornithine (monohydrochloride) added; B is the same solution alone; 2 mL held in the mouth for 5 s | 0.17 (text) | 1.33 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 trained people (mean±SE) | Without it more bitter Tested, significant |
| Mann–Whitney U test (* p<0.05, ** p<0.01 in the figures, against no addition). Direction shows which published value (text) is larger. The text says it was significantly smaller, and the 100 mM point in Fig. 2 has **. The authors say the concentrations of the mixed solution are close to those of commercial enteral nutrition solutions Where: Results and discussion; Fig. 2 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same BCAA solution, differing only in whether L-ornithine (or L-arginine) was added; rated by a small trained panel | |||||
| Bitterness intensity (sensory) | Isoleucine solution + 100 mM L-arginine vs isoleucine solution alone 100 mM L-isoleucine solution with 100 mM L-arginine added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.1 (approximate, from the figure) | 1.76 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 8 trained people (mean±SE) | Without it more bitter Test method described; result for this comparison not reported |
| Mann–Whitney U test (* p<0.05, ** p<0.01 in the figures, against no addition). Direction compares an approximate value read from the figure with a text value. The 100 mM L-arginine point in Fig. 1 has no mark, and no test result is given for this pair. For the leucine and valine solutions with 100 mM L-arginine in the same figure, the text says bitterness was "rather enhanced", but in the figure leucine sits at about the same level and valine lower; text and figure disagree, so they are not given rows Where: Results and discussion; Fig. 1 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same BCAA solution, differing only in whether L-ornithine (or L-arginine) was added; rated by a small trained panel; no test result | |||||
| Bitterness intensity (sensory) | Mixed BCAA solution + 100 mM L-arginine vs mixed BCAA solution alone mixed BCAA solution (28.1 mM L-isoleucine, 12.1 mM L-leucine, 60.7 mM L-valine) with 100 mM L-arginine added; B is the same solution alone; 2 mL held in the mouth for 5 s | 0.50 (text) | 1.33 (text) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 6 trained people (mean±SE) | Without it more bitter Tested, significant |
| Mann–Whitney U test (* p<0.05, ** p<0.01 in the figures, against no addition). Direction shows which published value (text) is larger. The text says it was significantly smaller, and the 100 mM point in Fig. 2 has * Where: Results and discussion; Fig. 2 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same BCAA solution, differing only in whether L-ornithine (or L-arginine) was added; rated by a small trained panel | |||||
Shiraishi 2017 sensory only
Suppression in Bitterness Intensity of Bitter Basic Drug by Chlorogenic Acid. Chemical & Pharmaceutical Bulletin 65(2):151-156 — doi:10.1248/cpb.c16-00670
- How deeply checked
- Checked in full text — Full text via the J-STAGE PDF (Methods; Results and discussion; Fig. 3); Fig. 3 was checked as a page image. Taste-sensor and NMR results are not given rows Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- 0.5 mM diphenhydramine hydrochloride (an antihistamine ingredient) solution with chlorogenic acid, quinic acid or caffeic acid added at 0.1, 0.5 and 1.0 mM each
- Processing and cooking
- Not applicable (simply added to solutions)
- How it was served or eaten
- 2 mL held in the mouth for 5 s; gargling and at least 20 min between samples
- Who rated, on what scale
- 6 trained healthy women in the methods, but n=10 in the Fig. 3 legend, which disagree; bitterness score 0–4 matched to quinine standards; figures show mean±SD; the test is Bonferroni in the methods but Tukey in the Fig. 3 legend, which disagree
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM chlorogenic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM chlorogenic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.2 (approximate, from the figure) | about 2.3 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Tested, significant |
| Direction shows which approximate value read from the figure is larger. Marks in Fig. 3 are against no addition: ** p<0.01. The number of raters is 6 trained women in the methods but n=10 in the Fig. 3 legend, which disagree. The test is also Bonferroni in the methods but Tukey in the Fig. 3 legend, which disagree; the marks follow the Fig. 3 legend (Tukey). The text says each ingredient alone was less bitter than the threshold. Readings from the figure have a margin of about ±0.1 Where: Methods (gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; the number of raters and the test name disagree between the methods and the figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM quinic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM quinic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 0.7 (approximate, from the figure) | about 2.3 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Tested, significant |
| Direction shows which approximate value read from the figure is larger. Marks in Fig. 3 are against no addition: *** p<0.001. The number of raters is 6 trained women in the methods but n=10 in the Fig. 3 legend, which disagree. The test is also Bonferroni in the methods but Tukey in the Fig. 3 legend, which disagree; the marks follow the Fig. 3 legend (Tukey). The text says each ingredient alone was less bitter than the threshold. Readings from the figure have a margin of about ±0.1 Where: Methods (gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; the number of raters and the test name disagree between the methods and the figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM caffeic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM caffeic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.2 (approximate, from the figure) | about 2.3 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Tested, significant |
| Direction shows which approximate value read from the figure is larger. Marks in Fig. 3 are against no addition: ** p<0.01. The number of raters is 6 trained women in the methods but n=10 in the Fig. 3 legend, which disagree. The test is also Bonferroni in the methods but Tukey in the Fig. 3 legend, which disagree; the marks follow the Fig. 3 legend (Tukey). The text says each ingredient alone was less bitter than the threshold. Readings from the figure have a margin of about ±0.1 Where: Methods (gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; the number of raters and the test name disagree between the methods and the figure | |||||
Okuno 2020 sensory only
Bitterness-Suppressing Effect of Umami Dipeptides and Their Constituent Amino Acids on Diphenhydramine: Evaluation by Gustatory Sensation and Taste Sensor Testing. Chemical & Pharmaceutical Bulletin 68(3):234-243 — doi:10.1248/cpb.c19-00736
- How deeply checked
- Checked in full text — Full text via the J-STAGE PDF (Methods; Results and discussion; Fig. 3); Fig. 3 was checked as a page image. Taste-sensor, surface plasmon resonance and molecular-model results are not given rows Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- 0.5 mM diphenhydramine hydrochloride solution with Glu-Glu, Asp-Asp or Gly-Gly (dipeptides) or Glu, Asp or Gly (amino acids) added; the added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods, and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree
- Processing and cooking
- Not applicable (simply added to solutions)
- How it was served or eaten
- 2 mL held in the mouth for 5 s (single-blind); gargling and at least 20 min between samples
- Who rated, on what scale
- 7 trained women; bitterness score 0–4 matched to quinine hydrochloride standards; figures show mean±SD; Tukey test
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM Glu-Glu (an umami dipeptide) vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM Glu-Glu (an umami dipeptide) added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 0.8 (approximate, from the figure) | about 1.9 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Tested, significant |
| Direction shows which approximate value read from the figure is larger. Tukey test (*** p<0.001 in Fig. 3, against no addition). Fig. 3 has *** at 1.0 mM. The added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree; this table gives rows only for 1.0 mM, common to all three. Readings from the figure have a margin of about ±0.1 Where: Methods (samples; gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; rated by 7 people, and the concentrations given disagree between the methods, abstract and figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM Asp-Asp (an umami dipeptide) vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM Asp-Asp (an umami dipeptide) added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 0.95 (approximate, from the figure) | about 1.9 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Tested, significant |
| Direction shows which approximate value read from the figure is larger. Tukey test (*** p<0.001 in Fig. 3, against no addition). Fig. 3 has *** at 1.0 mM. The added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree; this table gives rows only for 1.0 mM, common to all three. Readings from the figure have a margin of about ±0.1 Where: Methods (samples; gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; rated by 7 people, and the concentrations given disagree between the methods, abstract and figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM Gly-Gly (a dipeptide) vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM Gly-Gly (a dipeptide) added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.6 (approximate, from the figure) | about 1.9 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Test method described; result for this comparison not reported |
| Direction shows which approximate value read from the figure is larger. Tukey test (*** p<0.001 in Fig. 3, against no addition). Fig. 3 has no mark at 1.0 mM. The text says no such change was seen with Gly-Gly or Gly, but no test result is shown for each concentration (it is not described as not significant). The added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree; this table gives rows only for 1.0 mM, common to all three. Readings from the figure have a margin of about ±0.1 Where: Methods (samples; gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; rated by 7 people, and the concentrations given disagree between the methods, abstract and figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM L-glutamic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM L-glutamic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.15 (approximate, from the figure) | about 1.9 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Test results conflict between text and figure |
| Direction shows which approximate value read from the figure is larger. Tukey test (*** p<0.001 in Fig. 3, against no addition). The text says Glu lowered bitterness significantly at 0.5, 1.0 and 5.0 mM, but in Fig. 3 there is no mark at 1.0 mM (*** only at 5.0 mM). The disagreement between text and figure is left as it is. The added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree; this table gives rows only for 1.0 mM, common to all three. Readings from the figure have a margin of about ±0.1 Where: Methods (samples; gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; rated by 7 people, and the concentrations given disagree between the methods, abstract and figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM L-aspartic acid vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM L-aspartic acid added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.0 (approximate, from the figure) | about 1.9 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Tested, significant |
| Direction shows which approximate value read from the figure is larger. Tukey test (*** p<0.001 in Fig. 3, against no addition). Fig. 3 has *** at 1.0 mM (there is no mark at 0.5 mM, which disagrees at 0.5 mM with the text saying "significant at 0.5, 1.0 and 5.0 mM"). The added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree; this table gives rows only for 1.0 mM, common to all three. Readings from the figure have a margin of about ±0.1 Where: Methods (samples; gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; rated by 7 people, and the concentrations given disagree between the methods, abstract and figure | |||||
| Bitterness intensity (sensory) | Diphenhydramine solution + 1.0 mM glycine vs diphenhydramine solution alone 0.5 mM diphenhydramine hydrochloride solution with 1.0 mM glycine added; B is the same solution alone; 2 mL held in the mouth for 5 s | about 1.6 (approximate, from the figure) | about 1.9 (approximate, from the figure) | bitterness score 0–4 (matched to quinine hydrochloride standard solutions; higher is more bitter); mean of 7 trained women; values approximate, read from Fig. 3 (the source gives mean±SD) | Without it more bitter Test method described; result for this comparison not reported |
| Direction shows which approximate value read from the figure is larger. Tukey test (*** p<0.001 in Fig. 3, against no addition). Fig. 3 has no mark at 1.0 mM. The text says no such change was seen with Gly-Gly or Gly, but no test result is shown for each concentration (it is not described as not significant). The added concentrations are 0.5, 1.0 and 1.5 mM in the abstract, 0.1, 0.5 and 1.0 mM in the methods and 0.5, 1.0 and 5.0 mM in the results and Fig. 3, which disagree; this table gives rows only for 1.0 mM, common to all three. Readings from the figure have a margin of about ±0.1 Where: Methods (samples; gustatory sensation test; statistics); Results and discussion; Fig. 3 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — The same diphenhydramine solution, differing only in whether the ingredient was added; rated by 7 people, and the concentrations given disagree between the methods, abstract and figure | |||||
Sotoyama 2017 sensory only
Citric Acid Suppresses the Bitter Taste of Olopatadine Hydrochloride Orally Disintegrating Tablets. Biological & Pharmaceutical Bulletin 40(4):451-457 — doi:10.1248/bpb.b16-00828
- How deeply checked
- Checked in full text — Full text via the J-STAGE PDF (Methods; Table 1; Results; Fig. 1); Fig. 1 was checked as a page image (approximate bars and p values). Electronic-tongue results are kept apart from human ratings and not given rows Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride (an anti-allergy ingredient); the same coated granules (37.71 mg) with 0, 0.1, 1, 2.5, 5 and 10% citric acid (0–25.00 mg), with the excipient (Ludiflash) reduced by the same amount, 6 kinds (Table 1)
- Processing and cooking
- Tablets made by direct compression (using coated granules)
- How it was served or eaten
- The tablet was placed in the mouth and rated while it disintegrated, then rated again right after it was spat out; the mouth was rinsed with 120 mL of water and 15 min passed before the next tablet
- Who rated, on what scale
- 11 healthy adults (2 men, 9 women; 22.8±2.2 years); bitterness VAS 0–100 mm (0 = none, 100 = very bitter); figures show mean+SD; paired t-tests with Bonferroni correction, with p<0.01 taken as significant by the authors
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Tablet with 0.1% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 0.25 mg (0.1%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 198.29 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | during disintegration about 42, right after spitting out about 28 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | Without it more bitter Tested, not significant |
| Direction shows which published value is larger (the same direction at both time points). Paired t-tests with Bonferroni correction; the authors took p<0.01 as significant. Against no addition, p was 0.456 during disintegration and 0.094 right after spitting out, neither meeting the authors' threshold (which does not mean there is no difference). The text says bitterness during disintegration fell as the citric acid concentration rose, but the pairwise p values do not reach this threshold. Readings from the figure have a margin of about ±2. Tablets with flavouring and sweetener added (13 people) are on the sweetener and flavouring axis and are not given rows Where: Methods (tablet preparation; Table 1; gustatory sensation test; statistics); Results; Figs. 1a and 1b For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same coated granules and the same drug amount, differing in whether citric acid was included (the excipient was reduced by the same amount); paired ratings by 11 people with a test, but the authors' threshold was not met | |||||
| Bitterness intensity (sensory) | Tablet with 1% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 2.50 mg (1%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 196.04 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | during disintegration about 30, right after spitting out about 35 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | Without it more bitter Tested, not significant |
| Direction shows which published value is larger (the same direction at both time points). Paired t-tests with Bonferroni correction; the authors took p<0.01 as significant. Against no addition, p was 0.048 during disintegration and 0.624 right after spitting out, neither meeting the authors' threshold (which does not mean there is no difference). The text says bitterness during disintegration fell as the citric acid concentration rose, but the pairwise p values do not reach this threshold. Right after spitting out, the 1% tablet is higher than the 0.1% tablet, so the values do not fall steadily with the amount. Readings from the figure have a margin of about ±2. Tablets with flavouring and sweetener added (13 people) are on the sweetener and flavouring axis and are not given rows Where: Methods (tablet preparation; Table 1; gustatory sensation test; statistics); Results; Figs. 1a and 1b For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same coated granules and the same drug amount, differing in whether citric acid was included (the excipient was reduced by the same amount); paired ratings by 11 people with a test, but the authors' threshold was not met | |||||
| Bitterness intensity (sensory) | Tablet with 2.5% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 6.25 mg (2.5%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 192.29 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | during disintegration about 22, right after spitting out about 17 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | Without it more bitter Tested, not significant |
| Direction shows which published value is larger (the same direction at both time points). Paired t-tests with Bonferroni correction; the authors took p<0.01 as significant. Against no addition, p was 0.019 during disintegration and 0.020 right after spitting out, neither meeting the authors' threshold (which does not mean there is no difference). The text says bitterness during disintegration fell as the citric acid concentration rose, but the pairwise p values do not reach this threshold. Readings from the figure have a margin of about ±2. Tablets with flavouring and sweetener added (13 people) are on the sweetener and flavouring axis and are not given rows Where: Methods (tablet preparation; Table 1; gustatory sensation test; statistics); Results; Figs. 1a and 1b For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same coated granules and the same drug amount, differing in whether citric acid was included (the excipient was reduced by the same amount); paired ratings by 11 people with a test, but the authors' threshold was not met | |||||
| Bitterness intensity (sensory) | Tablet with 5% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 12.50 mg (5%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 186.04 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | during disintegration about 27, right after spitting out about 26 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | Without it more bitter Tested, not significant |
| Direction shows which published value is larger (the same direction at both time points). Paired t-tests with Bonferroni correction; the authors took p<0.01 as significant. Against no addition, p was 0.100 during disintegration and 0.213 right after spitting out, neither meeting the authors' threshold (which does not mean there is no difference). The text says bitterness during disintegration fell as the citric acid concentration rose, but the pairwise p values do not reach this threshold. During disintegration, the 5% tablet is higher than the 2.5% tablet, so the values do not fall steadily with the amount. Readings from the figure have a margin of about ±2. Tablets with flavouring and sweetener added (13 people) are on the sweetener and flavouring axis and are not given rows Where: Methods (tablet preparation; Table 1; gustatory sensation test; statistics); Results; Figs. 1a and 1b For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same coated granules and the same drug amount, differing in whether citric acid was included (the excipient was reduced by the same amount); paired ratings by 11 people with a test, but the authors' threshold was not met | |||||
| Bitterness intensity (sensory) | Tablet with 10% citric acid vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. Orally disintegrating tablets of 250 mg containing 5 mg olopatadine hydrochloride; the same coated granules (37.71 mg) with 25.00 mg (10%) citric acid, and the excipient (Ludiflash) reduced from 198.54 mg to 173.54 mg; B is the tablet without citric acid. Rated while the tablet disintegrated in the mouth, and again right after spitting it out | during disintegration about 20, right after spitting out about 24 (approximate, from the figure) | during disintegration 47, right after spitting out 40 (text) | bitterness VAS 0–100 mm (0 = none, 100 = very bitter); mean of 11 healthy adults (mean+SD); B is the text value and A is approximate, read from Figs. 1a and 1b | Without it more bitter Tested, not significant |
| Direction shows which published value is larger (the same direction at both time points). Paired t-tests with Bonferroni correction; the authors took p<0.01 as significant. Against no addition, p was 0.033 during disintegration and 0.105 right after spitting out, neither meeting the authors' threshold (which does not mean there is no difference). The text says bitterness during disintegration fell as the citric acid concentration rose, but the pairwise p values do not reach this threshold. Readings from the figure have a margin of about ±2. Tablets with flavouring and sweetener added (13 people) are on the sweetener and flavouring axis and are not given rows Where: Methods (tablet preparation; Table 1; gustatory sensation test; statistics); Results; Figs. 1a and 1b For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same coated granules and the same drug amount, differing in whether citric acid was included (the excipient was reduced by the same amount); paired ratings by 11 people with a test, but the authors' threshold was not met | |||||
Dadkhah 2025 sensory only
Development of 3D printed dexamethasone chewable tablets for prophylaxis of chemotherapy-induced nausea and vomiting in children. International Journal of Pharmaceutics: X 10:100380 — doi:10.1016/j.ijpx.2025.100380
- How deeply checked
- Checked in full text — Full text via the Europe PMC XML (Methods 2.6; Table 2; Results 3.2; Table 4); bitterness values are the means in Table 4 Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- 3D-printed chewable tablets of dexamethasone (a steroid ingredient) (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (the raw material is a 70% sorbitol solution) and others) with 3.00% GABA, 3.00% beta-cyclodextrin, both, or neither, 4 kinds (Table 2); a commercial tablet was also rated but is not a pair with an added ingredient and is not given a row
- Processing and cooking
- Formed with a semi-solid extrusion 3D printer
- How it was served or eaten
- After rinsing the mouth at least twice, the tablet was placed on the middle of the tongue, crushed between tongue and palate, held for 30 s and spat out; rated right after spitting out and at 2 min; at least 10 min between samples
- Who rated, on what scale
- 6 adult volunteers (5 rated at 2 min); bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; the tablets looked identical and were labelled only with a number, and the order was randomised, but the source says the test was not blinded; no test result for bitterness is published
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Tablet with 3.00% GABA vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. 3D-printed dexamethasone chewable tablets (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (Table 2; the raw material is a 70% sorbitol solution) and others in the same amounts in every tablet) with 3.00% GABA (gamma-aminobutyric acid); B is the tablet with neither added GABA nor beta-cyclodextrin. Crushed and held on the tongue for 30 s, rated right after spitting out and at 2 min | right after spitting out 20.40, at 2 min 13.89 (Table 4) | right after spitting out 30.08, at 2 min 12.26 (Table 4) | bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; mean of 6 adults (6 right after spitting out, 5 at 2 min) | Depends on the combination No test reported |
| Direction shows which published value (mean in Table 4) is larger. Right after spitting out the tablet with the ingredient is lower, and at 2 min it is higher (the direction splits by time point). No test result for bitterness is published. One person did not rate at 2 min, so the two time points are not read as a change over time in the same people. The tablets looked identical and were labelled only with a number, and the order was randomised, but the source says the test was not blinded. The text of Methods 2.6 says "sorbitol (22.00%)", while Table 2 says sorbitol solution 22.00% Where: Methods 2.6 (taste masking); Table 2; Results 3.2; Table 4 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same base and the same drug amount, differing in whether the ingredient was included; 6 people (5 at 2 min) and no test result. The base contains flavouring and sweetener in the same amounts in every tablet. The tablets are formulations built on a gel base (gelatin and others), and the pairs compare, between formulations on that same gel base, whether GABA or beta-cyclodextrin is added; this differs from studies that compare whether a gel is added as an additive (out of scope) | |||||
| Bitterness intensity (sensory) | Tablet with 3.00% beta-cyclodextrin vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. 3D-printed dexamethasone chewable tablets (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (Table 2; the raw material is a 70% sorbitol solution) and others in the same amounts in every tablet) with 3.00% beta-cyclodextrin; B is the tablet with neither added GABA nor beta-cyclodextrin. Crushed and held on the tongue for 30 s, rated right after spitting out and at 2 min | right after spitting out 41.48, at 2 min 28.54 (Table 4) | right after spitting out 30.08, at 2 min 12.26 (Table 4) | bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; mean of 6 adults (6 right after spitting out, 5 at 2 min) | With the added ingredient more bitter No test reported |
| Direction shows which published value (mean in Table 4) is larger. The tablet with the ingredient is higher at both time points. The authors call the lack of reduction counter-intuitive and did not establish a cause. This is a result in chewable tablets with this base and is not read as a general property of beta-cyclodextrin. No test result for bitterness is published. One person did not rate at 2 min, so the two time points are not read as a change over time in the same people. The tablets looked identical and were labelled only with a number, and the order was randomised, but the source says the test was not blinded. The text of Methods 2.6 says "sorbitol (22.00%)", while Table 2 says sorbitol solution 22.00% Where: Methods 2.6 (taste masking); Table 2; Results 3.2; Table 4 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same base and the same drug amount, differing in whether the ingredient was included; 6 people (5 at 2 min) and no test result. The base contains flavouring and sweetener in the same amounts in every tablet. The tablets are formulations built on a gel base (gelatin and others), and the pairs compare, between formulations on that same gel base, whether GABA or beta-cyclodextrin is added; this differs from studies that compare whether a gel is added as an additive (out of scope) | |||||
| Bitterness intensity (sensory) | Tablet with 3.00% GABA + 3.00% beta-cyclodextrin vs tablet without The amounts in this row are the composition of tablets made for the test, not a guide for dispensing or taking medicines. 3D-printed dexamethasone chewable tablets (1.00% dexamethasone, 2 mg per tablet); a common base (3.00% raspberry flavour, 0.10% saccharin sodium, 22.00% sorbitol solution (Table 2; the raw material is a 70% sorbitol solution) and others in the same amounts in every tablet) with both 3.00% GABA and 3.00% beta-cyclodextrin; B is the tablet with neither added GABA nor beta-cyclodextrin. Crushed and held on the tongue for 30 s, rated right after spitting out and at 2 min | right after spitting out 43.49, at 2 min 23.75 (Table 4) | right after spitting out 30.08, at 2 min 12.26 (Table 4) | bitterness VAS ("not at all bitter" to "extremely bitter") converted to 0–100%; mean of 6 adults (6 right after spitting out, 5 at 2 min) | With the added ingredient more bitter No test reported |
| Direction shows which published value (mean in Table 4) is larger. The tablet with the ingredients is higher at both time points. No test result for bitterness is published. One person did not rate at 2 min, so the two time points are not read as a change over time in the same people. The tablets looked identical and were labelled only with a number, and the order was randomised, but the source says the test was not blinded. The text of Methods 2.6 says "sorbitol (22.00%)", while Table 2 says sorbitol solution 22.00% Where: Methods 2.6 (taste masking); Table 2; Results 3.2; Table 4 For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Limited — Tablets with the same base and the same drug amount, differing in whether the ingredient was included; 6 people (5 at 2 min) and no test result. The base contains flavouring and sweetener in the same amounts in every tablet. The tablets are formulations built on a gel base (gelatin and others), and the pairs compare, between formulations on that same gel base, whether GABA or beta-cyclodextrin is added; this differs from studies that compare whether a gel is added as an additive (out of scope) | |||||
Sterneder 2024 sensory only
Identification of 4′-Demethyl-3,9-dihydroeucomin as a Bitter-Masking Compound from the Resin of Daemonorops draco. Journal of Agricultural and Food Chemistry 72(38):20991-20999 — doi:10.1021/acs.jafc.4c04583
- How deeply checked
- Checked in full text — Full text via the Europe PMC XML (Methods: paired comparison sensory test and statistics; Results; Table 2; legends of Figs. 2 and 4); the images of Figs. 2A and 4A were not obtained. Cell-assay results are not given rows Checked by: LLM (one extracted, another checked against the source; no human check), 2026-10-24.
- Samples
- Quinine 10 ppm in water with 500 ppm of an organic-solvent extract of the resin of dragon's blood palm (Daemonorops draco) (DD), its fractions I–XI (30 or 50 ppm), or 100 ppm of the isolated and synthesised compound DMDHE added
- Processing and cooking
- Not applicable (simply added to solutions)
- How it was served or eaten
- 2 samples (the quinine solution and the quinine solution with the addition) served with 3-digit codes and compared with a nose clip in a sensory room with yellow-red light
- Who rated, on what scale
- A trained panel (10–22 per row; 20 for the extract, 22 for DMDHE); the bitterness rating is 0–10 in the methods section but 0–100 in the results and figure legends, which disagree; paired t-tests; the statistics section says data are mean±SEM unless stated otherwise
| Measured | Comparison and condition | With the added ingredient | Without it | Unit | Direction / test |
|---|---|---|---|---|---|
| Bitterness intensity (sensory) | Quinine solution + 100 ppm DMDHE vs quinine solution alone Quinine 10 ppm in water with 100 ppm of 4′-demethyl-3,9-dihydroeucomin (DMDHE), a compound isolated from the resin of dragon's blood palm (Daemonorops draco) and later synthesised; B is the same quinine solution alone. Paired comparison of 2 samples, rated with a nose clip | 53.8±3.6 (text) | 64.1±3.7 (text) | bitterness rating 0–100 (0 = not bitter, 100 = very bitter; the methods section says 0–10, while the results and figure legends say 0–100); mean of a trained panel of 22 (the statistics section says data are mean±SEM unless stated otherwise) | Without it more bitter Tested, significant |
| Direction shows which published value (text) is larger. Paired t-test, p<0.01 (the Fig. 4A legend gives ** p≤0.01, n=22). The text gives the mean reduction in bitterness as 14.8±5.0%. The scale disagrees between the methods section (0–10) and the results and figure legends (0–100), and no conversion is described. The Fig. 4A image was not obtained Where: Methods (paired comparison sensory test); Results (sensory evaluation of DMDHE); Fig. 4A legend For whether, for the same bitter sample (a solution of quinine, amino acids or a medicine ingredient, or a medicine formulation), adding an ingredient while keeping the amount of the bitter component the same changes the intensity of bitterness people perceive compared with not adding it: Usable — The same quinine solution, differing only in whether the compound was added; paired comparison by 22 people with a test. The scale given differs between the methods and the results | |||||
What was established within an experiment
Only results observed in comparisons within the same study are given here. Results without a reported test are described as such.
- In a 0.1 mM quinine solution (11 people, scores 0–4), raising phosphatidic acid from 0.1% to 1.0% (w/v) gave about 0.9 and then about 0.2, approximately from the figure (about 1.6 without it). This study gives no test method or result for these pairs. In another study from the same laboratory (6 people), with the same 1.0% the isoleucine solution was 1.15 vs 1.68 and the phenylalanine solution 2.08 vs 2.62, neither with an individual mark in the figure. [rows: Nakamura 2002 (phosphatidic and tannic acids) Quinine + 0.1% (w/v) phosphatidic acid vs quinine alone; Nakamura 2002 (phosphatidic and tannic acids) Quinine + 1.0% (w/v) phosphatidic acid vs quinine alone; Ogawa 2004 Isoleucine solution + 1.0% (w/v) phosphatidic acid vs isoleucine solution alone; Ogawa 2004 Phenylalanine solution + 1.0% (w/v) phosphatidic acid vs phenylalanine solution alone]
- In BCAA solutions (6–8 trained people, scores 0–4), adding 100 mM L-ornithine changed the isoleucine solution from 1.76 to 1.01 and the mixed solution from 1.33 to 0.17, both significant. Adding 100 mM L-arginine to the mixed solution gave 0.50, also significant. The valine solution went from 1.20 to 0.58, but no significant difference was obtained. [rows: Tokuyama 2006 Isoleucine solution + 100 mM L-ornithine vs isoleucine solution alone; Tokuyama 2006 Mixed BCAA solution + 100 mM L-ornithine vs mixed BCAA solution alone; Tokuyama 2006 Mixed BCAA solution + 100 mM L-arginine vs mixed BCAA solution alone; Tokuyama 2006 Valine solution + 100 mM L-ornithine vs valine solution alone]
- Two studies added ingredients to a 0.5 mM diphenhydramine solution. In the study by Shiraishi and colleagues, 1.0 mM chlorogenic, quinic and caffeic acids (about 1.2, about 0.7 and about 1.2, approximately from the figure, against about 2.3 without) have significance marks in the figure. In the study by Okuno and colleagues, 1.0 mM Glu-Glu, Asp-Asp and L-aspartic acid have significance marks in the figure, while in the same figure 1.0 mM Gly-Gly and glycine have no marks (both about 1.6, against about 1.9 without), and the text says no such change was seen. [rows: Shiraishi 2017 Diphenhydramine solution + 1.0 mM chlorogenic acid vs diphenhydramine solution alone; Shiraishi 2017 Diphenhydramine solution + 1.0 mM quinic acid vs diphenhydramine solution alone; Shiraishi 2017 Diphenhydramine solution + 1.0 mM caffeic acid vs diphenhydramine solution alone; Okuno 2020 Diphenhydramine solution + 1.0 mM Glu-Glu (an umami dipeptide) vs diphenhydramine solution alone; Okuno 2020 Diphenhydramine solution + 1.0 mM Asp-Asp (an umami dipeptide) vs diphenhydramine solution alone; Okuno 2020 Diphenhydramine solution + 1.0 mM L-aspartic acid vs diphenhydramine solution alone; Okuno 2020 Diphenhydramine solution + 1.0 mM Gly-Gly (a dipeptide) vs diphenhydramine solution alone; Okuno 2020 Diphenhydramine solution + 1.0 mM glycine vs diphenhydramine solution alone]
- Adding 100 ppm DMDHE, a compound isolated from dragon's blood palm resin, to a 10 ppm quinine solution changed the rating from 64.1 to 53.8 (paired t-test, p<0.01, 22 people). [rows: Sterneder 2024 Quinine solution + 100 ppm DMDHE vs quinine solution alone]
Candidate explanations for the differences
Conditions that differ between studies and might explain differences in results, and the authors' interpretations. Several conditions differ at once, so which one mattered is not known. These are candidates, not causes.
- Even the same ingredient gives different results with different bitter samples. 0.15% (w/v) L-arginine lowered bitterness significantly in the isoleucine and quinine solutions, while for the phenylalanine solution no individual test result is shown. L-glutamic acid was higher with the addition in the quinine solution (approximate, from the figure). The authors write that tannic acid lowered bitterness at low concentrations and raised it at high concentrations, and attribute this to the astringency of tannic acid itself (the authors' interpretation). Why results change with the combination of bitter component and ingredient cannot be told from this comparison alone. [rows: Ogawa 2004 Isoleucine solution + 0.15% (w/v) L-arginine vs isoleucine solution alone; Ogawa 2004 Quinine solution + 0.15% (w/v) L-arginine vs quinine solution alone; Ogawa 2004 Phenylalanine solution + 0.15% (w/v) L-arginine vs phenylalanine solution alone; Ogawa 2004 Quinine solution + 0.15% (w/v) L-glutamic acid vs quinine solution alone; Ogawa 2004 Phenylalanine solution + 0.005% (w/v) tannic acid vs phenylalanine solution alone; Nakamura 2002 (phosphatidic and tannic acids) Quinine + 0.05% (w/v) tannic acid vs quinine alone]
- The relation between the amount added and the result is not always one-directional. In the citric acid tablets, the 5% tablet was higher than the 2.5% tablet during disintegration, and the 1% tablet higher than the 0.1% tablet right after spitting out (approximate, from the figure). Phosphatidic acid was lower at 1.0% than at 0.1%. The units of amount also differ between studies (mM, w/v, proportion of the tablet). [rows: Sotoyama 2017 Tablet with 0.1% citric acid vs tablet without; Sotoyama 2017 Tablet with 1% citric acid vs tablet without; Sotoyama 2017 Tablet with 2.5% citric acid vs tablet without; Sotoyama 2017 Tablet with 5% citric acid vs tablet without; Nakamura 2002 (phosphatidic and tannic acids) Quinine + 0.1% (w/v) phosphatidic acid vs quinine alone; Nakamura 2002 (phosphatidic and tannic acids) Quinine + 1.0% (w/v) phosphatidic acid vs quinine alone]
- The form of the sample differs. Besides studies that added ingredients to solutions, two studies included them in tablets. In tablets that disintegrate in the mouth, or chewable tablets that are crushed and spat out, how the ingredient dissolves and how long it stays in the mouth may differ from a solution (a guess). The chewable-tablet study added the ingredients to a common base that already contained flavouring and sweetener. [rows: Sotoyama 2017 Tablet with 2.5% citric acid vs tablet without; Dadkhah 2025 Tablet with 3.00% GABA vs tablet without; Dadkhah 2025 Tablet with 3.00% beta-cyclodextrin vs tablet without]
- The number of raters is 5–22 depending on the condition and time point, and with few raters the uncertainty of the estimates can be larger (a guess). The scales also differ, from scores of 0–4 matched to quinine standards to VAS and ratings of 0–100, so values cannot be compared across studies. [rows: Dadkhah 2025 Tablet with 3.00% GABA vs tablet without; Sterneder 2024 Quinine solution + 100 ppm DMDHE vs quinine solution alone; Shiraishi 2017 Diphenhydramine solution + 1.0 mM chlorogenic acid vs diphenhydramine solution alone]
What is not known — what this comparison alone cannot separate
- Five of the eight included studies are reports from the same laboratory. Their scales and procedures share some parts but differ in others, such as the volume held in the mouth and for how long. Some rows share the same raters or the same control, so the number of rows is not treated as the number of independent studies. There is no study in this table that checked the same combination of ingredient and bitter sample outside that laboratory. [rows: Nakamura 2002 (phosphatidic and tannic acids) Quinine + 1.0% (w/v) phosphatidic acid vs quinine alone; Ogawa 2004 Isoleucine solution + 0.15% (w/v) L-arginine vs isoleucine solution alone; Tokuyama 2006 Mixed BCAA solution + 100 mM L-ornithine vs mixed BCAA solution alone; Shiraishi 2017 Diphenhydramine solution + 1.0 mM quinic acid vs diphenhydramine solution alone; Okuno 2020 Diphenhydramine solution + 1.0 mM Asp-Asp (an umami dipeptide) vs diphenhydramine solution alone]
- For pairs with sour ingredients such as citric acid, whether the bitterness score fell because the sourness made the bitterness less noticeable or through some other mechanism cannot be separated by this comparison alone. Umami dipeptides and amino acids also have tastes of their own. [rows: Sotoyama 2017 Tablet with 2.5% citric acid vs tablet without; Okuno 2020 Diphenhydramine solution + 1.0 mM Glu-Glu (an umami dipeptide) vs diphenhydramine solution alone]
- For pairs with no individual test result shown, it cannot be said that a significant difference was shown for that pair. Separately, approximate values read from a figure are limited in reading precision (the margin is given in each row's note). [rows: Nakamura 2002 (phosphatidic and tannic acids) Quinine + 0.1% (w/v) phosphatidic acid vs quinine alone; Ogawa 2004 Quinine solution + 0.15% (w/v) L-lysine vs quinine solution alone; Dadkhah 2025 Tablet with 3.00% GABA vs tablet without; Dadkhah 2025 Tablet with 3.00% beta-cyclodextrin vs tablet without]
- Why the chewable tablet with 3.00% beta-cyclodextrin was higher than the tablet without was not established by the authors either, and cannot be told from this one study. This is the only study in this table in which people's bitterness values with beta-cyclodextrin added were checked in full text. An abstract-only study reports that adding beta-cyclodextrin to a bitter gourd extract lowered bitterness markedly; it is on hold (see the table of what we looked at). [rows: Dadkhah 2025 Tablet with 3.00% beta-cyclodextrin vs tablet without; Dadkhah 2025 Tablet with 3.00% GABA + 3.00% beta-cyclodextrin vs tablet without]
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. Rows from the same study include rows that share the same raters or the same control and are not independent (even within one paper, the number of raters can differ by condition or time point). The five reports from the same laboratory at Mukogawa Women's University (with the same corresponding author) are counted as one research group in the ledger. The number of sources shown automatically below is the number of all sources in the table. The sucrose and salt pairs of one paper are held by another page, and this page sets up a separate study entry for that paper's phosphatidic acid and tannic acid pairs, but the paper is counted once.
- Sources in the table: 8, of which 8 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): 37. Rows on perceived bitterness: 37.
- 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: 4 (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 looked at for this question, and why each was included or excluded, are recorded here. Sources on bitterness-suppressing ingredients already in the lab's ledger were reviewed, and Europe PMC and J-STAGE were searched with combinations of ingredient terms (amino acids, cyclodextrins, resins, lactoferrin, citric acid and others) and bitterness and sensory terms; candidates with full text were saved and read. Studies that could be read only in the abstract were not put in the table and are on hold, because the pairs of bitterness values, the number of raters and the scale cannot be confirmed. Pairs for which the source does not let us confirm that the amount of the bitter component was the same are also on hold. Studies adding sugar, salt, sweeteners or flavourings, studies comparing a gel as the additive or mixing into food, treatments that remove the bitter component, comparisons between different formulations, studies that compared the physical coating itself (with or without coating, amount of coating) as the factor (comparisons that use the same coated granules and include an ingredient are included, with the accompanying replacement of excipient given in the conditions), studies using only taste sensors or other instruments, and studies that measured only acceptability or aversion rather than bitterness are recorded as out of scope with the reason. Studies combining medicines with each other are left outside the range of ingredients for this question (an editorial scope decision). The search described here is a record and does not show that nothing was missed.
| Source | Decision | Why |
|---|---|---|
| The effect of various substances on the suppression of the bitterness of quinine-human gustatory sensation, binding, and taste sensor studies (2002) doi | Included in the table | Eleven people compared bitterness scores for quinine solutions with phosphatidic acid or tannic acid added (approximate values from the figure; no pairwise test results). The sucrose and NaCl pairs of the same paper are on the sugar-and-salt page. The higher tannic acid concentration is not given a row because text and figure disagree |
| The Combination Effect of L-Arginine and NaCl on Bitterness Suppression of Amino Acid Solutions (2004) doi | Included in the table | Six people compared bitterness scores for amino acid and quinine solutions with phosphatidic acid, tannic acid, L-arginine, L-lysine or L-glutamic acid added; ten representative pairs, including ones that rose, are given rows. The sucrose, aspartame and NaCl pairs are on the sweetener and salt axis and are not given rows |
| Bitterness Suppression of BCAA Solutions by L-Ornithine (2006) doi | Included in the table | Six to eight trained people compared bitterness scores for BCAA solutions with L-ornithine or L-arginine added, with tests. The leucine and valine solutions with L-arginine are not given rows because text and figure disagree |
| Suppression in Bitterness Intensity of Bitter Basic Drug by Chlorogenic Acid (2017) doi | Included in the table | Bitterness scores for diphenhydramine solutions with chlorogenic, quinic or caffeic acid added were compared; the rows note that the number of raters and the test name disagree between the methods and the figure. The three pairs at 1.0 mM are given rows |
| Bitterness-Suppressing Effect of Umami Dipeptides and Their Constituent Amino Acids on Diphenhydramine: Evaluation by Gustatory Sensation and Taste Sensor Testing (2020) doi | Included in the table | Seven women compared bitterness scores for diphenhydramine solutions with umami dipeptides and amino acids added. Because the concentrations given disagree between the abstract, methods and figure, only the six pairs at 1.0 mM, common to all three, are given rows |
| Synergistic Effects of Sour Taste and Low Temperature in Suppressing the Bitterness of Aminoleban EN (2011) doi | Read as context (not in the table) | On hold. The pairs of bitterness intensity for BCAA solutions with tartaric acid added (Fig. 2B) had been missed among the candidates and were once given rows after the check, but have been taken out. The source says BCAA solutions were mixed with tartaric acid solutions, but the mixing ratio and final concentrations are not stated, so it cannot be confirmed that the amount of the bitter component was the same. In Fig. 2B, the 2 conditions of BCAA at τ2 and τ2.5 with tartaric acid at τ4 have significance marks (the other conditions have none). The flavoured-powder and temperature pairs for the nutritional product in the same paper are on the page on mixing bitter medicines into food or drink. The pairs with sucrose added are on the sweetener axis |
| Citric Acid Suppresses the Bitter Taste of Olopatadine Hydrochloride Orally Disintegrating Tablets (2017) doi | Included in the table | Eleven people compared bitterness VAS for five formulations of olopatadine hydrochloride orally disintegrating tablets with citric acid included at the same drug amount and for the tablet without, with tests (no pair reaches the authors' threshold). Tablets with flavouring and sweetener added are on the sweetener and flavouring axis and are not given rows |
| Development of 3D printed dexamethasone chewable tablets for prophylaxis of chemotherapy-induced nausea and vomiting in children (2025) doi | Included in the table | Six people (5 at 2 min) compared bitterness VAS for dexamethasone chewable tablets with GABA or beta-cyclodextrin included; no test result for bitterness. The tablets are formulations built on a gel base (gelatin and others), and the pairs compare, between formulations on that same gel base, whether GABA or beta-cyclodextrin is added; this differs from studies that compare a gel as the additive (excluded), so it is included. The comparison with a commercial tablet is not a pair with an added ingredient and is not given a row |
| Identification of 4′-Demethyl-3,9-dihydroeucomin as a Bitter-Masking Compound from the Resin of Daemonorops draco (2024) doi | Included in the table | The pair of ratings for quinine solution with DMDHE, a compound from dragon's blood palm resin (22 people, tested), is given a row. For the extract of the resin (500 ppm, 20 people), the text reports a decrease, a mean change of −29.6±6.30%, p≤0.001. The pair of ratings is in Fig. 2A, but the image was not obtained, so the numbers are not confirmed and it is not given a row in the table. The changes for each fraction (Table 2) do not share concentration and number of raters and are not given rows |
| Modulation of bitter taste perception by a small molecule hTAS2R antagonist (2010) doi | Excluded | A study adding the bitter-receptor antagonist GIV3727 to sweetener (acesulfame K, saccharin) solutions; it has pairs of human bitterness ratings. This question narrows the bitter samples to quinine, amino acids, medicine ingredients and similar, so this study, whose bitter samples are sweeteners, is left out |
| Preparation and Evaluation of Poly-γ-glutamic Acid Hydrogel Mixtures with Amlodipine Besylate: Effect on Ease of Swallowing and Taste Masking (2019) doi | Excluded | There are bitterness pairs comparing amlodipine with and without mixing into gels (poly-gamma-glutamic acid, agar, carrageenan), with human ratings (for agar too the published mean fell, with no significance mark in the figure). Comparing a gel as the additive is close to medication jellies and overlaps with the page on mixing bitter medicines into food or drink, so it is not covered in this question |
| The effect of carboxymethyl cellulose and beta-cyclodextrin as debittering agents on bitterness and physicochemical properties of bitter gourd extract (2023) doi | Read as context (not in the table) | On hold (abstract only). The abstract says carboxymethyl cellulose and beta-cyclodextrin were added to a bitter gourd extract, a trained panel rated bitterness, and with 0.75% (w/v) beta-cyclodextrin bitterness fell significantly by more than 90%. It may fall within scope, but the full text could not be obtained for this question (the PMC body could not be retrieved), and the pairs of ratings, number of raters and scale have not been checked |
| Influence of sodium chloride treatment and polysaccharides as debittering agent on the physicochemical properties, antioxidant capacity and sensory characteristics of bitter gourd (Momordica charantia) juice (2017) doi | Read as context (not in the table) | On hold. There are conditions with carboxymethyl cellulose or gum arabic added to bitter gourd juice, and the abstract says "5% gum arabic reduced bitterness". The material saved for this question goes only as far as the abstract, and the pairs of ratings, number of raters, scale and pairwise tests have not been checked. The salt-water treatment in the same paper is covered on another page |
| Naringenin-lactoferrin binding: Impact on naringenin bitterness and thermodynamic characterization of the complex (2020) doi | Read as context (not in the table) | On hold (abstract only). The abstract says that with lactoferrin added to naringenin, a trained panel's time-intensity analysis showed maximum bitterness down by 27% and overall bitterness by 33%. The number of raters, amount added, original ratings, scale and tests are not in the abstract, and the full text (subscription) was not read |
| Improving the palatability of Platycodonic Radix for pediatric use: Integrating LC-MS-based bitter component profiling with an HP-beta-Cyclodextrin/xylitol taste-masking strategy (2026) doi | Read as context (not in the table) | On hold (abstract only). It reports a formulation adding HP-beta-cyclodextrin and xylitol (a sweetener) to a decoction of balloon flower root, described in the abstract as the most effective. The concentrations are by weight relative to the root and cannot be read as concentrations in the whole liquid. It is a combination added together with a sweetener, and the number of raters, values and tests are not in the abstract |
| Debittering of bitter gourd juice using beta-cyclodextrin: Mechanism and effect on antidiabetic potential (2018) doi | Read as context (not in the table) | On hold (abstract only). A study adding beta-cyclodextrin to bitter gourd juice; the numbers in the abstract are acceptability scores, and pairs of bitterness intensity cannot be confirmed. The measurements in the full text were not read |
| Mechanistic investigation of a soybean protein isolate–soyasaponin–pectin composite system on soyasaponin bitterness in an acidic environment (2025) doi | Read as context (not in the table) | On hold. A soy protein–soyasaponin–pectin composite system with sensory evaluation by 10 people. The scale and evaluation details are in supplementary material that was not obtained, and whether the final saponin concentration is the same at each ratio cannot be confirmed |
| Performance of macroporous resins for debittering HLB-affected grapefruit juice and its impacts on furanocoumarin and consumer sensory acceptability (2021) doi | Excluded | Treatment that removes the bitter components of grapefruit juice by adsorption on resins, so the amount of the bitter components falls; what was measured was overall acceptability |
| Postprandial Glucose Reduction by Pomelo Albedo Treated with β-Cyclodextrin and Ultrasound (2025) doi | Excluded | Pomelo albedo treated with beta-cyclodextrin solution, with the solids recovered and dried, so the amount of the bitter components falls (a removal treatment); the sensory scale and the table values also disagree |
| Preparation and In Vitro, In Vivo Evaluation of Clarithromycin Microcapsules (2010) PubMed | Excluded | A comparison between different formulations (a home-made microcapsule formulation and a commercial one) rated by 18 people in all (9 per formulation); not a pair differing only in an added coating material |
| In Vivo Investigation of (2-Hydroxypropyl)-β-cyclodextrin-Based Formulation of Spironolactone in Aqueous Solution for Paediatric Use (2022) doi | Excluded | There is a saturated-solution control without the excipient for the HP-beta-cyclodextrin formulation, but the drug concentration differs between control and formulation (0.024 mg/mL vs 1 mg/mL), and the scale is an aversion VAS, not bitterness intensity |
| Responsive Sensory Evaluation to Develop Flexible Taste-Masked Paediatric Primaquine Tablets against Malaria for Low-Resource Settings (2023) doi | Excluded | A study optimising sweetener and flavouring combinations, on the sweetener axis; the text says commercial bitterness blockers were not effective, but there are no values or tests for pairs with a blocker added alone |
| Taste-Masking Effect of Physical and Organoleptic Methods on Peppermint-Scented Orally Disintegrating Tablet of Famotidine Based on Suspension Spray-Coating Method (2012) doi | Excluded | Famotidine orally disintegrating tablets combining coating of the drug (a physical method) with sweetener and flavouring (peppermint). There is also a series without sweetener or flavouring that changes only whether the drug is coated (Table 1 and Fig. 3; median bitterness VAS 54 vs 77, 31 people), but these studies make the physical coating itself (with or without coating, amount of coating) the factor compared, so they are left out (comparisons that use the same coated granules and include an ingredient are included, with the accompanying replacement of excipient given in the conditions) |
| Combination Effect of Physical and Gustatory Taste Masking for Propiverine Hydrochloride Orally Disintegrating Tablets on Palatability (2015) doi | Excluded | Propiverine hydrochloride orally disintegrating tablets combining the amount of drug coating with sweetener and flavouring. There is also a series with the drug fixed at 10 mg that changes the amount of coating without sweetener or flavouring (Table 1), but these studies make the physical coating itself (with or without coating, amount of coating) the factor compared, so they are left out (comparisons that use the same coated granules and include an ingredient are included, with the accompanying replacement of excipient given in the conditions) |
| Effects of Flavors on Taste Sensation of Pioglitazone Orally Disintegrating Tablets (2024) doi | Excluded | Orally disintegrating tablets with flavourings added; the added materials are flavourings |
| Improved Palatability of Gummy Drugs of Epinastine Hydrochloride Using Organoleptic Taste-Masking Methods (2023) | Excluded | Gummy formulations combining sweeteners, flavourings and others; the added materials are sweeteners and flavourings |
| The Inhibitory Effect of Adenylic Acid on the Bitterness of the Antibacterial Combination Drug Trimethoprim/Sulfamethoxazole (2023) doi | Excluded | The bitterness evaluation with adenylic acid added uses taste-sensor and other instrument values, and cannot be given rows as pairs of human ratings |
| Taste-Masking Effect of Chlorogenic Acid (CGA) on Bitter Drugs Evaluated by Taste Sensor and Surface Plasmon Resonance on the Basis of CGA-Drug Interactions (2017) doi | Excluded | A study of chlorogenic acid–drug binding by taste sensor and surface plasmon resonance; not taken as new pairs of human bitterness ratings (the human test is in the separate paper by Shiraishi and colleagues, 2017) |
| The suppression of enhanced bitterness intensity of macrolide dry syrup mixed with an acidic powder. (2007) doi | Excluded | A study including mixing of medicines with each other, filtrates, order of preparation and jelly comparisons; close to the axis of mixing medicines and mixing into jelly (the scope of the page on mixing bitter medicines into food or drink) |
| Masking the Taste of Fixed-Dose Combination Drugs: Particular NSAIDs Can Efficiently Mask the Bitterness of Famotidine. (2023) doi | Excluded | There is a human comparison with NSAIDs added to famotidine solution (5 people), but it is a combination of active medicines and is left outside the range of ingredients for this question (an editorial scope decision) |
| A homoeriodictyol sodium mouthwash reduces bitterness sensitivity in patients with gynecological cancer receiving carboplatin-based chemotherapy. (2026) doi | Excluded | According to the candidate comparison, a study comparing the bitterness of caffeine solution before and after a mouthwash, not a pair with an ingredient added to the sample. The source was not saved for this question, and the number of people, values and tests have not been checked |
Source ledger
The source for each study in the table can be followed from its section. All of the lab's sources are listed in the source ledger (in Japanese).
How to cite this page
Aoki, M. (NIGAMI LAB) (2026). Do added ingredients make a bitter sample less bitter?. https://nigamilab.com/en/topics/additives-bitter-sample-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