taste-mixture suppression
concept / concept-taste-mixture-suppression
味混合による抑制
Taste-mixture suppression is a reduction in the perceived intensity of one tastant when multiple tastants are mixed. Record it with stimulus, concentration, and individual variation rather than as a universal rule.
On this page (5 sections)
Reading the bitterness
Taste mixture suppression occurs when simultaneously tasting multiple tastants makes the perceived intensity of one or both weaker than when presented alone. It is condition-dependent, varying with stimulus combination, concentration, and assessor, rather than a universal law.
In a sensory study adding sucrose to caffeine or quinine, adults with a genotype associated with greater sensitivity of the sweet receptor TAS1R3 had greater bitterness reduction. A genotype associated with higher sensitivity to PROP, involving bitter receptor TAS2R38, showed a tendency toward stronger suppression but did not reach statistical significance. The effect therefore varied by bitter substance, age, and receptor genotype.
In a test combining 5 weak bitter substances with sodium salts, sucrose, or other additives, suppression in two-component mixtures was in many cases approximately the mean of suppression when each component was added alone. There were exceptions; the authors described this as an approximate observation within the concentrations tested, not a law generalizable to all complex foods or untested bitter substances.
A sensory panel mixing sucrose into aqueous caffeine or instant-coffee solutions observed mutual suppression: even after components were adjusted to subjectively similar strengths when presented alone, overall taste and flavor intensity after mixing was less than simple addition. The source is behind a subscription barrier, so numerical size and direction of suppression could not be checked.
In a human trial (n=107) comparing decaffeinated coffee with 200 mg added caffeine (equivalent to one strong cup) against a quinine condition adjusted to similar bitterness, both the coffee itself and a subsequently presented sucrose solution were rated less sweet with added caffeine. Bitterness, sourness, saltiness, and umami did not differ significantly. The authors proposed that caffeine might alter taste responses through adenosine receptors, but the study did not directly measure a receptor-level mechanism.
When the fatty acid oleic acid was added at a concentration of 0.5 millimolar, the bitterness of quinine hydrochloride and promethazine hydrochloride was significantly weakened in a human sensory paired-comparison test. However, adding oleic acid at the same concentration did not significantly weaken the bitterness of caffeine. Titration calorimetry confirmed an exothermic binding between oleic acid and quinine hydrochloride, showing a boundary in which a fat-derived fatty acid masks bitterness by forming a complex with the bitter substance, while it is less effective against bitter substances that dissolve readily in water.
Sources for this overview
Checked for this overview: Confirmed that the phenomenon depends on individual differences. / Confirmed that suppression differs by genotype.
The influence of sodium salts on binary mixtures of bitter-tasting compounds
Checked for this overview: Confirmed the linear approximation and its exceptions.
Checked for this overview: Only the existence of mutual suppression could be checked.
Checked for this overview: Checked the selective reduction in sweetness and the mechanistic hypothesis.
Identification of bitterness-masking compounds from cheese
Checked for this overview: Used for the significant suppression of quinine and promethazine by oleic acid, the non-significance for caffeine, and the ITC confirmation of binding
Hypotheses and recipe candidates for this entry are on the Japanese page.
Structured claims — open a section to read each claim's confidence, evidence and limits
Sensory (8)
Scope: Mennella et al.'s child and adult study, and Keast et al.'s bitter-mixture study
Note: The genotype effect differs by compound, and the difference for PROP did not reach statistical significance.
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concept-taste-mixture-suppression —has_perceived_bitterness_affected_by→ "The bitter substance tested, age, and individual differences related to TAS1R3 and TAS2R38"Scope: The 5 weak bitter substances tested by Keast et al., with salt and sucrose
Note: An approximation within the tested range, not a law covering complex foods or every bitter substance.
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concept-taste-mixture-suppression —is_partially_predicted_by→ "For binary bitter mixtures, the average of the suppression rate for each component"Scope: Human-panel intensity ratings of two-component caffeine-sucrose and coffee-sucrose mixtures (1990).
Note: The publisher's abstract and full text are both behind a subscription barrier; the account is limited to an abstract summary accessible through a bibliographic database. Numerical size and direction of suppression were not checked and are not recorded.
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concept-taste-mixture-suppression —has_perceived_bitterness_suppressed_by→ "Sucrose added to aqueous caffeine or instant-coffee solutions. Calvino and colleagues (1990) reported mutual suppression in human panel ratings of two-component caffeine-sucrose and coffee-sucrose mixtures. Concentrations had been adjusted to yield subjectively similar strengths for the individual components, yet overall taste and flavor intensity was less than their simple sum."Scope: A human sensory panel test comparing caffeine added to decaffeinated coffee against a quinine control condition (n=107)
Note: The adenosine-receptor-mediated mechanism is the authors' proposal; the test itself did not directly measure a receptor-level mechanism. No extrapolation is made to coffee and sugar confectionery in general.
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concept-taste-mixture-suppression —reduces_taste_preference_for→ "A human sensory test (Choo et al., 2017; n=107) comparing decaffeinated coffee containing 200 mg of caffeine (equivalent to 1 cup of strong coffee) against a quinine condition adjusted to a matching level of bitterness. In the caffeine condition, both the sweetened coffee itself and a subsequently presented sucrose solution were rated as less sweet. This treatment, however, had no significant effect on ratings of bitterness, sourness, saltiness, or umami. The authors offer, as one possible explanation for this result, that caffeine's antagonism of adenosine receptors may alter taste response (a contested mechanistic hypothesis)."Scope: Layer: solution. An experiment combining a human sensory paired-comparison test (one-tailed binomial test, significance level 5%) using oleic acid solubilized as its sodium salt, with isothermal titration calorimetry (ITC).
Note: The way suppression takes effect appears to depend on the hydrophobicity of the bitter substance, and no significant suppression was seen for caffeine, which has low lipid solubility. The authors discuss that oleic acid masks bitterness by forming a complex with the bitter substance. A separate finding from the same paper (bitterness masking by free fatty acids derived from cheese) is included in the existing ingredient-cheese entry.
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concept-taste-mixture-suppression —has_perceived_bitterness_suppressed_by→ "Adding 0.5 mM free oleic acid (solubilized as the sodium salt) significantly suppressed the bitterness of 0.22 mM quinine hydrochloride (paired comparison with 20 panelists, one-tailed binomial test p=0.0059) and of 1.5 mM promethazine hydrochloride (6 panelists, p=0.0156). By contrast, the bitterness of 50 mM caffeine (10 panelists) was not significantly suppressed (p=0.0547). Isothermal titration calorimetry confirmed an exothermic binding between oleic acid and quinine hydrochloride with a dissociation constant of 11±1 µM."Scope: Analytical sensory evaluation using komatsuna green juice as the sample, and GC/MS measurement of allyl isothiocyanate. Limited to what appears in a conference abstract (a society meeting abstract). The abstract does not give the number of panelists or the statistical method
Note: The abstract split the bitterness peculiar to komatsuna into sourness, astringency and pungency as evaluation items (5 items: sourness, astringency, pungency, sweetness and umami); it did not measure bitterness as 1 item. The green juice is not a dish; it is a sample for simply examining the flavor of dairy products and vegetables. As a conference abstract, it has not been peer reviewed. This is the result for mixed green juice, not the result of adding dairy products afterward to a finished dish.
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concept-taste-mixture-suppression —has_perceived_bitterness_suppressed_by→ "Milk fat. Komatsuna (Japanese mustard spinach) green juice (pressed with a slow juicer and strained through gauze) was mixed 4 to 1 with a solution or processed milk in which the amount of milk protein, lactose or milk fat was varied in 3 steps, and the taste was evaluated on a line scale using the green juice alone as the reference. Increasing milk fat weakened the sourness, astringency and pungency, which were listed as the components of komatsuna bitterness, and strengthened sweetness and umami. Changing the amount of milk protein did not change the intensity of any taste. Increasing lactose strengthened only sweetness. Allyl isothiocyanate, a pungent component, was also reduced by milk fat."Scope: 40 students (median age 14) and 23 teachers (median age 49) at Niigata Meikun Junior High School. Commercial bitter gourd powder was used as the model bitter food, and each food was taken into the mouth together with it for evaluation. All foods were at room temperature. After the Friedman test, comparisons with the control used the Wilcoxon signed-rank test (Holm correction). Open-label, with the samples presented to everyone in the same order (the effect of order was not separated)
Note: Bitter gourd powder is a model standing in for the bitterness of dishes, and this was not a test of adding foods to a finished dish. The samples were taken into the mouth at evaluation, held for 5 seconds and spat out. The score for each food is not in the text but only in Figure 5 (the text states only whether differences were significant). The foods were grouped by taste quality by the authors (chocolate syrup and condensed milk have fats and oils and viscosity as well as sweetness), so it cannot be separated which of sweetness, saltiness or fats and oils was responsible. The miso soup was 15 g of liquid miso diluted 10-fold with water. Open-label, and the number of participants was not decided from statistical power. The authors consider the possibilities that fats and oils or viscosity coated the bitter substances and made it harder for them to reach the taste buds, and that sourness was perceived as a separate unpleasant sensation (speculation).
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concept-taste-mixture-suppression —has_perceived_bitterness_suppressed_by→ "Commercial foods mixed with bitter gourd powder as a model of bitterness (not a dish). 1.0 g of bitter gourd powder was mixed with 10 mL of a liquid or 10 g of a solid or semi-solid commercial food, and 40 junior high school students and 23 teachers rated bitterness on a 0 to 10 numerical scale (0 = not bitter, 10 = bitter). The bitterness of the control mixed with mineral water had a median of 8 for students and 6 for teachers. In students, the bitterness score was significantly lower than the control for 7 foods: chocolate syrup, condensed milk and smooth red bean paste (sweetness), nori tsukudani and miso soup (saltiness and umami), and unsalted butter and fresh cream (fats and oils) (P<0.001 after Holm correction), while lemon juice and unsweetened yogurt (sourness) showed no significant decrease. In teachers, lemon juice and unsweetened yogurt were also significantly lower in addition to these 7 foods (P<0.05)."Scope: 20 people, excluding 5 excluded from 25 healthy volunteers. Sample was 1 g of drug plus food. The screening was one evaluation per food. The comparison of the 5 foods with swallowing jelly was in the main test (the same 20 people, repeated 3 times). In addition to bitterness, sweetness, sourness, pungency, aftertaste and smell were evaluated. The bitter drug was a commercial stomach medicine (in 3 g of powder containing zedoary 2500 mg and others)
Note: The source of bitterness is a crude drug preparation (a medicine), not the bitterness of a dish. That milk, yogurt, honey, marmalade, retort curry and instant miso soup are not among the 5 is a reading from the text's statement that 5 foods (and 1 by a one-sided test) were significant; the value for each food is only in Figure 1 (no numbers in the text). This test was one evaluation per food, and the strength of taste, amount and temperature of the foods (ice cream was ice cold) were not uniform. The authors presume that the foods that worked have a strong taste and viscosity and cover the drug, loosening its contact with the taste buds (speculation). In another study (Sugai 2026, bitter gourd powder) miso soup significantly lowered bitterness, so how foods work may change with the kind of bitter substance and the evaluation method.
Show data
concept-taste-mixture-suppression —has_perceived_bitterness_suppressed_by→ "Foods mixed into a bitter powder. 1 g of powder of a commercial crude drug preparation based mainly on zedoary was mixed with 20 mL (liquid) or 20 g (semi-solid) of each of 30 kinds of food, and 20 healthy people rated bitterness on a 5-point scale (1 = none to 5 = strong). The crude drug preparation alone scored 4.1, and in a two-sided test (Bonferroni correction) bitterness was significantly lower for only 5 foods: condensed milk 2.8, vanilla ice cream 2.9, chocolate ice cream 3.0, peanut cream 2.6 and nori tsukudani 2.1. Swallowing jelly for medicines for powdered medicine (3.1) was significant only in a one-sided test. The text states explicitly that milk cocoa did not show significant bitterness suppression, and milk, yogurt, honey, marmalade, retort curry, instant miso soup and others are not among the 5. In the main test, in which the same 20 people compared them with swallowing jelly (9-point rating, repeated 3 times), these 5 foods also showed a significant bitterness-masking effect exceeding that of swallowing jelly for medicines for powdered medicine (the comparison was against swallowing jelly, not against the drug alone). The authors state that the foods that suppressed bitterness have in common a strong taste and relatively high viscosity."