Kahudi and Kharoli from Assam are solid-fermented products made from mustard seeds. The preparation and analysis confirm a process of natural fermentation with acidic or alkaline additives. What this material shows is the raw material and process of the fermented products, not a measurement of the bitterness of mustard seed alone.
Allyl isothiocyanate (AITC), a hydrolysis product of mustard seed, was added to curry-flavored rice and evaluated by 88 consumers. In the descriptions, bitterness increased at both 0.123 mg/100 mL and 0.115 mg/100 mL for the unencapsulated form, and at 0.123 mg/100 mL for the encapsulated form. The mean values by condition can be checked in Table 2: all 4 treatment groups were higher than the control (1.4), at 3.0 to 3.4. However, the explanation in the abstract and conclusion (that the encapsulated form did so only at the detection threshold) does not match the table. The test used a commercially isolated reagent, so it is not a result from cooking mustard seed itself.
A separate abstract states that fully hydrolyzing mustard seeds and then leaching them with 60°C hot water yielded mustard powder with reduced bitterness while containing 0.355-0.392 g/100 g of allyl isothiocyanate. However, sensory scores showing the reduction in bitterness and quantitative values for the bitter constituent cannot be confirmed from the abstract.
In samples of pressed, defatted white mustard (Sinapis alba) meal kneaded with water and stored, bitterness appeared as the pungency faded. In reports from 1965 and 1966, bitterness became markedly stronger on day 13 when stored at 30°C, while no bitterness was perceived even after 138 days at 0°C and −2°C (a panel of 6). The crystals that the authors consider the main bitter component were identified as sinapine thiocyanate (sinapin rhodanide), and the threshold in a panel of 8 was about 0.08%. These were water-kneaded samples without added vinegar, so this is not a measurement of the bitterness of commercial mustard made with vinegar. The curry-flavored rice test above used a commercially isolated reagent, so its samples and methods differ.
Checked for this overview: Matched the scope: the raw material of Kahudi and Kharoli, natural fermentation with additives, and the limitation that the bitterness of mustard seed alone was not measured.
Dolan E; Faraone N; McSweeney MB / 2025 / journal article / full text checked
Checked for this overview: For the consumer evaluation (88 people) of curry-flavored rice with added isolated AITC, we separated the stated concentrations and encapsulation conditions, the mean values by condition (Table 2), and the discrepancy with the explanation in the abstract and conclusion.
Checked for this overview: Matched the scope: 60°C hot-water leaching after full hydrolysis, AITC content, and the point that the abstract does not give specific values for the reduction in bitterness.
YAMANISHI Tei; KOBAYASHI Akio; OYAMADA Sachiko / 1965 / journal article / full text checked
Checked for this overview: A storage test of white mustard kneaded with water (a panel of 6). It records bitterness on day 13 at 30°C and on day 138 at 0°C and −2°C.
KOBAYASHI Akio; SAIDA Yoriko; YAMANISHI Tei / 1966 / journal article / full text checked
Checked for this overview: Identification of the crystals that the authors consider the main bitter component, and a threshold of 0.08% in a panel of 8.
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Composition and content (1)
mustard seed — major bitter compound: From the bitter prepared mustard, crystals that the authors consider the main bitter component were isolated and identified as sinapine thiocyanate (sinapin rhodanide). An aqueous solution of this substance was strongly bitter, and the bitterness threshold in a panel of 8 was about 0.08% (w/v). The amount in the deteriorated prepared mustard was calculated from the yield to be about 0.1% (w/v), which was judged sufficient to give bitterness.preliminary
Scope: Crystals isolated from a white mustard (Sinapis alba) water paste that had turned bitter (pressed, defatted meal kneaded with water and stored). Not commercial mustard made with vinegar. The pungency had disappeared and the mustard had become bitter (deteriorated); the yield was about 0.3% from 1 kg of meal and 2 L of water. It was not confirmed in black mustard or in vinegar-containing prepared mustard.
Note: Identification was by elemental analysis, qualitative reactions and spectra. The judgment that this is the "main bitter component" is the authors', and should be read separately from the identification of the substance. The content is a value calculated from the yield, not a direct quantification. Another crystal isolated in the 1st report (p-hydroxybenzyl alcohol) was only slightly bitter and was not considered the cause of the strong bitterness. At the time of the 1st report, the analytical values for this crystal included impurities, which were corrected in the 2nd report.
The English abstract states that the bitter component was isolated as crystals and identified as sinapin rhodanide (sinapine thiocyanate) by chemical and physical methods. The introduction states that crystal I from the first report (p-hydroxybenzyl alcohol) was only slightly bitter and was not considered the cause of the strong bitterness, while crystal II "was strongly bitter and was thought to be the main bitter component". The results state that an aqueous solution of crystal II was slightly acidic (pH 4.2) and strongly bitter, and that the bitterness threshold in a panel of 8 was about 0.08% w/v; since 1 kg of mustard meal and 2 L of water make a volume of about 3 L, the amount of this substance in the deteriorated prepared mustard was calculated from the yield to be about 0.1% w/v, an amount sufficient to give bitterness. Summary (1) states that what was thought to be the main bitter component was separated from the deteriorated prepared mustard and identified as sinapin rhodanide.
Limitations: How the threshold was determined (the concentration steps and the judging method) is not described in detail in the text. The identification relies on analytical methods of the 1960s. "Main component" is the authors' judgment, and not the result of examining all other bitter components.
mustard seed increases Adding allyl isothiocyanate (AITC), a hydrolysis product of mustard seeds, to curried rice at its detection-threshold concentration significantly increased bitterness intensity whether or not the AITC was encapsulated.supported
Scope: Layer: food. An experiment adding isolated AITC reagent rather than mustard seeds themselves. Curried rice received AITC at the detection threshold (0.123 mg/100mL) or below it (0.115 mg/100mL), with and without encapsulation, and was evaluated by consumers (n=88) using RATA.
Encapsulated AITC raised bitterness and spiciness only when added at the detection threshold and did not suppress sweetness. Unencapsulated AITC, at both concentration levels, suppressed the sweetness of the curried rice and increased the intensity of bitterness and spiciness. The Results state that adding AITC at both levels (encapsulated and unencapsulated) significantly increased the bitterness of the samples (p < 0.05), and cite Green and Hayes 2004 and Sindhu et al. 2012 for the association of AITC with bitterness.
Limitations: AITC was added as a commercial reagent, and the measurement was not made on a food prepared from mustard seed itself. The mean bitterness intensities and standard deviations are given in Table 2, and we also checked the correspondence by condition (control 1.4; encapsulated: 3.0 at the detection threshold, 2.9 below the threshold; unencapsulated: 3.4 at the detection threshold, 3.1 below the threshold). In Table 2, all 4 treatment groups are higher than the control, but the explanation in the abstract and conclusion that "the encapsulated form increased bitterness and pungency only at the detection threshold" does not match Table 2 for the encapsulated, below-threshold group. The phrase "only when added at the detection threshold" in this row is a sentence from the abstract.
mustard seed shows the sensory response When 88 consumers evaluated curry-flavored rice with added AITC (a hydrolysis product of mustard seed) using the rate-all-that-apply (RATA) method (a 10-point intensity scale), the mean bitterness intensity was 1.4±1.0 for the control, versus 3.0±1.1 for the encapsulated-AITC detection-threshold group, 2.9±1.4 for the encapsulated-AITC below-threshold group, 3.4±1.5 for the unencapsulated-AITC detection-threshold group, and 3.1±1.2 for the unencapsulated-AITC below-threshold group, with all 4 treatment groups significantly higher than the control (indicated by statistical letter notation, p<0.05)supported
Scope: Dolan et al. 2025, Table 2; curry-flavored rice; 88 consumers; rate-all-that-apply (RATA) method; 10-point intensity scale
The Bitter row of Table 2: Control 1.4±1.0(b), Spray-dried AITC AD (encapsulated, detection threshold) 3.0±1.1(a), Spray-dried AITC BD (encapsulated, below threshold) 2.9±1.4(a), AITC AD (unencapsulated, detection threshold) 3.4±1.5(a), AITC BD (unencapsulated, below threshold) 3.1±1.2(a). Under the statistical notation where differing superscript letters indicate a significant difference, the control (b) differs significantly from all 4 treatment groups (all a).
Limitations: AITC is a commercially isolated reagent (allyl isothiocyanate), and the result is not from cooking mustard seed directly. Only statistical letter notation is given; the actual test method and the p-values themselves are described elsewhere in the text. This is the same experiment and the same source as the existing claim. In Table 2, all 4 treatment groups are higher than the control, but the explanation in the abstract and conclusion that "the encapsulated form increased bitterness and pungency only at the detection threshold" does not match Table 2 for the encapsulated, below-threshold group. Because the abstract and conclusion do not agree with the reading of this table, differences by condition should be read from the values in the table.
mustard seed — bitterness develops depending on: Prepared mustard made by kneading white mustard (Sinapis alba) seed meal with water loses pungency and becomes bitter during storage. This change differed greatly with storage temperature. At 30°C the pungency disappeared in 3 days and bitterness became markedly stronger on day 13. At room temperature (15 to 20°C), the pungency disappeared in 31 days and the bitterness became very strong. At 0°C and −2°C no bitterness was perceived at all even after 138 days, and at −20°C no perceptible change occurred (a panel of 6).preliminary
Scope: A sample of pressed, defatted white mustard (Sinapis alba) meal kneaded with water and stored. It is not commercial mustard made with vinegar. Meal from Dutch white mustard, pressed and defatted, was kneaded with twice its amount of water, left at 37°C for 2 hours to hydrolyze, and stored in a closed container. It was a water-only prepared mustard with no vinegar or other additions. Black mustard was not examined.
Note: In a 1965 report, the panel was 6 people and the scores were symbols (4 grades). It is counted as 1 source together with the 2nd report from the same laboratory. It does not say that commercial mustard made with vinegar becomes bitter in this way (the effect of vinegar is a separate claim).
The English abstract states that prepared white mustard loses pungency and becomes bitter during storage at room temperature, that the speed depends greatly on temperature, and that there was slight deterioration at 0°C and below and none at −20°C. Table 1 (with a note that the panel of 6 always gave the same result) shows pungency and bitterness in 4-grade symbols. At 30°C, pungency was "completely lost" from day 3, and the bitterness on days 13, 18 and 31 is marked "very bitter". At room temperature on day 31, pungency was "completely lost" and bitterness "very bitter". At 0°C on day 138, pungency was "weak" and bitterness "not perceived at all". At −2°C on day 138, pungency was "slightly reduced" and bitterness "not perceived at all". At −20°C, neither pungency nor bitterness changed up to day 138 (pungency the same as immediately after preparation, bitterness not perceived at all). The main text states: "In the sample stored at 30°C the pungency disappeared after 3 days, bitterness also arose slightly, and on day 13 the bitterness became markedly strong."
Limitations: A panel of 6 and a 4-grade evaluation by symbols; there are no statistics on scores. The bitterness symbol for day 3 at 30°C in the table appears to differ from the main text's "arose slightly", so the strength on day 3 is not stated in the claim, which is written only within the range of "markedly stronger on day 13". The sample was kneaded with water only, not commercial vinegar-containing mustard.
mustard seed — bitterness is generated by: The authors consider the development of bitterness in prepared white mustard as follows. When p-hydroxybenzylisothiocyanate, the pungent component, is hydrolyzed to an alcohol and the pungency disappears, thiocyanate ions (SCN⁻) are produced. These form a salt with sinapin, which is originally present in mustard seed, and markedly strengthen the bitterness. They add the reservation that whether this reaction is enzymatic or non-enzymatic cannot easily be decided.preliminary
Scope: The authors' interpretation for a white mustard (Sinapis alba) water paste (pressed, defatted meal kneaded with water and stored). Not commercial mustard made with vinegar. This is the authors' discussion, and the reaction pathway was not directly measured and shown (the description is limited to SCN⁻ having been detected and quantified in the ethanol extract with ferric chloride solution).
Note: Written within the scope of the authors' discussion. The same report states that heating freshly prepared mustard in a boiling water bath for 1 hour (an attempt to inactivate enzymes) had almost no effect on the development of bitterness (the storage temperature after heating is not specified).
The discussion states that it has long been known that p-hydroxybenzylisothiocyanate, the pungent component of white mustard, liberates rhodanide (SCN⁻) through the action of alkali, and that Virtanen and other researchers reported that hydrolysis of isothiocyanate glycosides with myrosinase produces part of the SCN⁻; the authors also write that they detected and quantified SCN⁻ in the ethanol extract of deteriorated mustard with ferric chloride solution. They then write that the development of bitterness can be explained if the pungent component is hydrolyzed to an alcohol and loses its pungency, and the SCN⁻ produced at that time forms a salt with sinapin, which is already present from the hydrolysis of glycosides, markedly increasing bitterness. Summary (2) says that the formation of a salt between sinapin and the SCN⁻ produced when the pungency disappears is "thought to be" the mechanism of bitterness development. It further states that whether this reaction is enzymatic or non-enzymatic is difficult to decide easily and requires further study.
Limitations: The liberation of rhodanide by the action of alkali and the action of myrosinase on glycosides were cited separately as earlier work. SCN⁻ was detected and quantified, but no result is shown that directly confirms the whole proposed reaction pathway (increased bitterness through the salt of SCN⁻ and sinapin).
mustard seed provides the material for Kahudi and Kharolisupported
Scope: Solid-fermented mustard seed products from Assam
Note: This is not direct evidence that mustard seed is a 『苦いスパイス』 (in translation: "bitter spice"), but evidence of its use as raw material for a fermented seasoning.
Preparation and analysis confirmed that both products use mustard seed as the raw material and undergo natural fermentation together with an acidic or alkaline additive.
Limitations: This is evidence about the raw material, not a measurement of mustard seed's own bitterness attribute.
mustard seed can be debittered by: It has been reported that fully hydrolyzing mustard seeds (Brassica juncea) and then leaching them with hot water produced mustard powder with reduced bitterness while retaining allyl isothiocyanate content.preliminary
Scope: Layer: food. Commercial mustard seeds (multiple particle sizes), treated by hot-water leaching (60°C) after complete hydrolysis.
Note: The full text could not be accessed (Elsevier journal, not open access). The full abstract was checked in Europe PMC's abstractText field. Numerical changes in protein, fat, and AITC content by particle size are given, but the abstract does not reveal specific measurements of bitterness reduction (such as sensory scores).
The main purpose of the investigation was to process mustard seeds into mustard powder while retaining pungency and reducing bitterness. Complete hydrolysis followed by hot-water leaching reduced bitterness while preserving pungency. Mustard kernels with an AITC content of 0.355–0.392 g/100 g and reduced bitterness could be obtained through complete hydrolysis followed by leaching at 60 °C.
Limitations: Because the full text was not accessed, specific sensory scores for the degree of bitterness reduction or chemical-analysis values quantifying bitter constituents cannot be checked from the abstract.
mustard seed — perceived bitterness is affected by: When acetic acid was added to a concentration of 4% in the prepared mustard, the onset of bitterness at room temperature (daytime temperature 18 to 20°C) was delayed by about 20 days compared with the untreated sample. The authors state that the fact that all commercial prepared mustards are made with vinegar helps to prevent this deterioration.preliminary
Scope: A test adding acetic acid to a white mustard (Sinapis alba) water paste (pressed, defatted meal kneaded with water and stored). Not commercial mustard made with vinegar itself. This was a test with added acetic acid, and the report does not describe how the number of days of delay was measured (number of panelists, judging method). It does not say that bitterness does not appear (it is only delayed).
Note: Within the range that acetic acid delayed the onset of bitterness. It is not a measurement of actual commercial vinegar-containing products. The 1-hour heating was a separate experiment and is not included in this claim.
The report, in examining conditions that prevent the development of bitterness in prepared mustard, states that the sample to which acetic acid was added to a concentration of 4% in the prepared mustard showed onset of bitterness delayed by about 20 days at room temperature (daytime temperature 18 to 20°) compared with the untreated sample. It writes that all commercial prepared mustards are made with vinegar, and that this proves that vinegar helps to prevent deterioration. The heating experiment (a) and the −20°C result (c) in the same passage are separate matters and are not included in this row.
Limitations: The number of panelists, the judging method and the scores are not described. The difference of 20 days is an approximate value.