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Title: A chemical basis for sour taste perception of acid solutions and fresh-pack dill pickles

item Johanningsmeier, Suzanne
item McFeeters, Roger

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2007
Publication Date: 8/8/2007
Citation: Da Conceicao Neta, E.R., Johanningsmeier, S.D., Drake, M.A., McFeeters, R.F. A chemical basis for sour taste perception of acid solutions and fresh-pack dill pickles. Journal of Food Science. 72(6):S352-S359.

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 shows there is a linear relationship between how sour acids are in water solutions or in dill pickles, provided we know how much of the acids present are in a certain chemical form. We can determine how much acid is in the sour chemical form with a simple measurement and some calculations. Surprisingly, we found that when acids are in the correct chemical form, they are all equally sour. With this information, we will be better able to predict and control the sour taste in modifying or creating new food formulations.

Technical Abstract: Sour taste is influenced by pH and acids present in foods. It is not currently possible, however, to accurately predict and modify sour taste intensity in foods containing organic acids. The objective of this study was to investigate the roles of protonated (undissociated) organic acid species and hydrogen ions in evoking sour taste. Sour taste intensity increased linearly with hydrogen ion concentration (R2= 0.995), and with the concentration of protonated organic acid species at pH 3.5 (R2 = 0.884), 4.0 (R2 = 0.929), and 4.5 (R2 = 0.970). The type of organic acid did not affect sour taste perception after adjusting for the effects of protonated organic acid species and hydrogen ions. Protonated organic acid species and hydrogen ions produced approximately the same sour taste response on a molar basis. Sour taste intensity was also linearly related to the total concentration of protonated organic acid species in fresh-pack dill pickles (R2 = 0.957). This study shows that the sour taste of organic acids is directly related to the number of molecules with at least one protonated carboxyl group plus the hydrogen ions in solution. Conclusions from these results are that all protonated organic acids are equally sour on a molar basis, that all protonated species of a given organic acid are equally sour, and that hydrogen ions and protonated organic acids are about equally sour on a molar basis.