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Title: Effects of pH adjustment and sodium ions on sour taste intensity of organic acids

Author
item NETA, E. R. D. - NC STATE UNIVERSITY
item Johanningsmeier, Suzanne
item DRAKE, MARYANNE - NC STATE UNIVERSITY
item McFeeters, Roger

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2009
Publication Date: 5/5/2009
Citation: Neta, E., Johanningsmeier, S.D., Drake, M., McFeeters, R.F. 2009. Effects of pH adjustment and sodium ions on sour taste intensity of organic acids. Journal of Food Science. 74(4):S165-S169.

Interpretive Summary: Sour taste is one of the five basic taste sensations. The intensity of sour taste in foods increases as the amounts of acids with hydrogen ions increase. However, other components of food may either enhance or suppress the perceived sour taste intensity. This article describes the effects that pH adjustment and salt have in reducing the sour taste intensity of solutions of single acids or mixtures of food acids.

Technical Abstract: Protonated organic acid species have been shown to be the primary stimuli responsible for sour taste of organic acids. However, we have observed that sour taste may be modulated when the pH of acid solutions is raised using sodium hydroxide. Objectives were to evaluate the effect of pH adjustment on sour taste of equimolar protonated organic acid solutions, and to investigate the potential roles of organic anions and sodium ions on sour taste perception. Despite equal concentrations of protonated acid species, sour taste intensity decreased significantly with increased pH for acetic, lactic, malic, and citric acids (P < 0.05). Total organic anion concentration did not explain the suppression of sour taste in solutions containing a blend of three organic acids with constant concentration of protonated organic acid species and hydrogen ions and variable organic anion concentrations (R2 = 0.480, P = 0.12). Sour taste suppression in these solutions seemed to be more closely related to sodium ions added in the form of NaOH (R2 = 0.861, P = 0.007). Addition of 20 mM NaCl to acid solutions resulted in significant suppression of sour taste (P = 0.016). However, sour taste did not decrease with further addition of NaCl up to 80 mM. Presence of sodium ions was clearly shown to decrease sour taste of organic acid solutions. Nonetheless, suppression of sour taste in pH adjusted single acid solutions was greater than what would be expected based on the sodium ion concentration alone, indicating an additional suppression mechanism may be involved.