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Flavor research: the Perception of Sour Taste

In a recent study, scientists at Monell Chemical Senses Center report that genes play a large role in determining individual differences in sour taste perception. The findings may help researchers identify the still-elusive taste receptor that detects sourness in foods and beverages, just as recent gene studies helped uncover receptors for sweet and bitter taste.

Scientists have long known that sour taste is stimulated by acids in foods and beverages. However, it is still not completely understood how the taste system is able to detect and translate acidic molecules on the tongue into a neural signal that the brain perceives as ‘sour.’

In this study, researchers tested 74 pairs of monozygotic (MZ, identical) twins and 35 pairs of dizygotic (DZ, fraternal) twins to determine the lowest concentration needed for each twin to correctly identify a citric acid solution as ‘sour.’

Because MZ twins have nearly identical genes while DZ twins share only about 50% of their genes, more similar responses in MZ than DZ pairs suggests that genes help determine sensitivity to the taste in question. Responses were compared within the twin pairs, and then entered into a computer model to determine the relative contributions of genetic and environmental influences on sour taste sensitivity.

The models estimated that genes played a more important role than environment in determining individual differences in sour taste sensitivity, accounting for 53% of the variation.

The finding that genes influence sour taste perception suggests that genetic analyses could potentially help identify sour receptors. Future studies will evaluate possible receptors by determining whether individual differences in genes for these structures—such as the recently-discovered PKD ion channel—are correlated with individual differences in sensitivity to sourness. For any given candidate receptor, a strong association of genetic with perceptual variation would support the likelihood that the receptor detects sour taste.

The findings, in conjunction with previous work on sweet, bitter, and umami (savory) taste, suggest that people differ in how they perceive the taste of foods, and that these differences are determined in part by their taste genes. So someone who inherited a high sensitivity to sour taste may find foods containing lemons or vinegar off-putting, whereas the same foods may be better accepted by a person whose genes make them less sensitive.

The researchers for this study were: Paul Wise, Danielle Reed and Paul Breslin of Monell and Jonathan Hansen from the Queensland Institute of Medical Research in Brisbane, Australia.

The full study was published in Chemical Senses online on July 10.

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