taste-mixture suppression

Scope: Adults in Mennella et al.'s study (gLMS ratings and genotype; only adults were genotyped)

Note: The genotype effect differs by compound, and the difference for PROP did not reach statistical significance. (2026-10-22, expansion stage N5 stage C batch 6: Codex's check against the source confirmed that the abstract only says bitterness was suppressed in both children and adults, without showing a difference by age, and that Keast et al.'s study is not among the evidence for this claim. Age was removed from the object and Keast et al.'s study from the scope; the status stays supported.)

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.

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.

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.

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.

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.

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 bitter food chosen with taking bitter medicines in mind, and this was not a test of adding foods to a finished dish. The samples were held in the mouth for 5 seconds; participants were told that in principle they should spit them out after evaluation, but whether to swallow was left to their own choice. The interaction between age group (students and teachers) and food was not tested. 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).

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 (20 people selected from 39, 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.