Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2004
Publication Date: 2/1/2005
Citation: Johanningsmeier, S.D., McFeeters, R.F., Drake, M.A. 2005. A hypothesis for the chemical basis for perception of sour taste. Journal of Food Science. 70:R44-R48.
Interpretive Summary: Sourness is one of the four basic taste sensations. Sourness is caused by the acids naturally present or added to foods. However, there is no general way to predict the relative sourness of different acids in foods. The only way to determine how sour different amounts or kinds of acids will be perceived has been to add them to a food recipe and then taste the food. This paper describes a new hypothesis which, if it proves to be correct after it is tested scientifically, would provide a method to mathematically predict how sour a food recipe will be perceived by consumers.
Technical Abstract: Sourness can be considered the simplest of the basic tastes in that it is related to hydrogen ions. However, there is not a sufficiently clear understanding of that relationship to allow sourness intensity to be predicted and rationally modified in foods. Based upon analysis of sensory data from our laboratory and re-analysis of previously published data, we propose a new hypothesis for the chemical basis for sourness perception. The intensity of sourness perception in acid solutions or acidified foods is linearly related to the molar concentration of all organic acid species with at least one protonated carboxyl group plus the molar concentration of free hydrogen ions. This hypothesis implies that, on a molar basis, different organic acids will be equally sour, provided at least one carboxyl group is protonated. The major effect of pH on sourness will be to determine the degree of protonation of organic acids. If this hypothesis is confirmed, it will provide a new understanding of the chemical basis for this basic taste perception and have broad usefulness in the formulation of products in which sour taste is an important component of flavor.