U.S. Dept. of Agriculture, Agricultural Research Service, SEA, Food Science Research Unit, NC State Univ., 322 Schaub Hall, Box 7624, Raleigh, NC, 27695-7624, USA.
Clorox Company, 4900 Johnson Drive, Pleasanton, CA, 94588, USA.
J Food Sci. 2020 Apr;85(4):910-917. doi: 10.1111/1750-3841.15018. Epub 2020 Mar 21.
The pH of most acid food products depends on undefined and complex buffering of ingredients but is critically important for regulatory purposes and food safety. Our objective was to define the buffer capacity (BC) of ingredients in salad dressing products. Ingredients of salad dressings were titrated individually and in combination using concentrations typical of dressing products. Titration curves from pH 2 to 12 were generated with sodium hydroxide and hydrochloric acid, which were then used to generate BC curves. A matrix of concentration and pK values for a series of monoprotic buffers approximated the pH of each ingredient. Some buffer series required anion or cation corrections for accurate pH prediction, possibly due to the presence of salts of acid or bases. Most buffers had BC values less than 10-fold the BC of acetic acid (0.25 β) typically in dressing formulations and had little influence on the final product pH of the dressings tested. Unexpectedly, we found that sugars in dressing formulations, including sucrose or corn syrup, exhibited buffering at pH values greater than 11 (0.035 β and 0.059 β, respectively), which was likely due to weakly acidic hydroxyl groups on the sugar molecules. However, the concentration and pK for buffers above pH 11 or below pH 2 were difficult to quantify due to the BC of water. The BC data may help to quantify the effects of salad dressing ingredients on the final product pH and benefit regulatory agencies and manufacturers in assessing product pH and safety. PRACTICAL APPLICATION: Buffer capacity data for salad dressing ingredients may help determine the influence ingredient addition will have on the final pH of a salad dressing product. The addition of low acid ingredients with little or no buffering may not significantly alter pH. The modeling method may be useful for regulatory purposes to estimate the effects of low acid ingredients on pH changes for food safety and may also be useful for product development of acid and acidified foods.
大多数酸性食品的 pH 值取决于成分的未定义和复杂缓冲作用，但对于监管目的和食品安全至关重要。我们的目标是定义沙拉酱产品中成分的缓冲能力 (BC)。单独和组合使用典型的调味产品浓度对沙拉酱的成分进行滴定。使用氢氧化钠和盐酸生成 pH 值为 2 至 12 的滴定曲线，然后使用这些曲线生成 BC 曲线。一系列一元缓冲剂的浓度和 pK 值矩阵近似于每种成分的 pH 值。一些缓冲剂系列需要阴离子或阳离子校正以准确预测 pH 值，这可能是由于存在酸或碱的盐。大多数缓冲剂的 BC 值都小于通常在调味配方中使用的乙酸的 10 倍 (0.25β)，对测试的调味剂的最终产品 pH 值影响不大。出乎意料的是，我们发现调味剂配方中的糖，包括蔗糖或玉米糖浆，在 pH 值大于 11 时表现出缓冲作用 (分别为 0.035β和 0.059β)，这可能是由于糖分子上的弱酸性羟基。然而，由于水的 BC，在 pH 值大于 11 或低于 2 时缓冲剂的浓度和 pK 值难以量化。BC 数据可帮助量化沙拉酱成分对最终产品 pH 值的影响，并使监管机构和制造商受益于评估产品 pH 值和安全性。实际应用：沙拉酱成分的缓冲能力数据可能有助于确定成分添加对沙拉酱产品最终 pH 值的影响。添加具有少量或没有缓冲作用的低酸性成分可能不会显著改变 pH 值。该建模方法可能有助于监管目的，以估计低酸性成分对食品安全中 pH 值变化的影响，并且对于酸性和酸化食品的产品开发也可能有用。
