Da Conceicao Neta E R, Johanningsmeier S D, Drake M A, McFeeters R F
US Department of Agriculture, Agricultural Research Service, Raleigh, NC, USA.
J Food Sci. 2007 Aug;72(6):S352-9. doi: 10.1111/j.1750-3841.2007.00400.x.
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 (R(2)= 0.995), and with the concentration of protonated organic acid species at pH 3.5 (R(2)= 0.884), 4.0 (R(2)= 0.929), and 4.5 (R(2)= 0.975). The structures of organic acid molecules did not affect sour taste after adjusting for the effects of protonated organic acid species and hydrogen ions. Sour taste intensity was also linearly related to the total concentration of protonated organic acid species in fresh-pack dill pickles (R(2)= 0.957). This study showed that the sour taste of organic acids was directly related to the number of molecules with at least 1 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 approximately equal in sour taste on a molar basis. This study provides a new understanding of the chemical species that are able to elicit sour taste and reveals a basis for predicting sour taste intensity in the formulation of acidified foods.
酸味受食物中存在的pH值和酸的影响。然而，目前还无法准确预测和改变含有有机酸的食物中的酸味强度。本研究的目的是调查质子化（未离解）有机酸种类和氢离子在引发酸味中的作用。酸味强度随氢离子浓度呈线性增加（R² = 0.995），并在pH 3.5（R² = 0.884）、4.0（R² = 0.929）和4.5（R² = 0.975）时随质子化有机酸种类的浓度呈线性增加。在调整了质子化有机酸种类和氢离子的影响后，有机酸分子的结构不影响酸味。酸味强度也与新鲜包装的莳萝泡菜中质子化有机酸种类的总浓度呈线性相关（R² = 0.957）。本研究表明，有机酸的酸味与溶液中至少有1个质子化羧基的分子数量加上氢离子直接相关。这些结果得出的结论是，所有质子化有机酸在摩尔基础上酸味相同，给定有机酸的所有质子化种类酸味相同，并且氢离子和质子化有机酸在摩尔基础上酸味大致相等。本研究为能够引发酸味的化学物质提供了新的理解，并揭示了在酸化食品配方中预测酸味强度的基础。
