柠檬黄、日落黄在含乳饮料中褪色分析及改进

Analysis and improvement on fading of tartrazine and sunset yellow in milk beverage

目的分析人工偶氮类色素柠檬黄、日落黄在含乳饮料中的褪色原因。方法通过测定Lab值,比色法计算其ΔE值,对比柠檬黄和日落黄与β-胡萝卜素在普通水体系以及含乳体系中的褪色速率,同时设计试验对比以乳清分离蛋白和酪朊酸钠作为蛋白质来源体系中复配柠檬黄日落黄色素的褪色速度,并使用Ellman’s法测定两者体系中巯基的数量。通过测定不同浓度半胱氨酸体系中复配柠檬黄日落黄色素的褪色情况,验证巯基数量对合成偶氮类色素褪色的影响。结果在普通水体系中复配柠檬黄日落黄稳定性较好,褪色速度较慢,而在含乳体系中复配柠檬黄日落黄色素的褪色速度快于天然色素。Ellman’s法测定乳清分离蛋白的巯基数量远远大于酪朊酸钠,同时乳清蛋白体系中复配柠檬黄日落黄色素褪色速度快于酪朊酸钠体系。半胱氨酸浓度梯度实验显示,半胱氨酸浓度越高复配柠檬黄日落黄色素褪色越快。结论通过不同实验法案能够确定,含乳饮料中的巯基是导致合成偶氮类色素快速褪色的原因之一。

Objective To analyze the reasons for the color fading of tartrazine and sunset yellow in milk beverages. Methods The fading rates of mixed artificial color and β-carotene in water as well as milk beverage systems were compared using the colorimetry and the value of ΔE. In addition, the fading rates of mixed artificial color in the systems of whey protein isolate and sodium caseinate were also compared, and Ellman＇s method was applied to determine the amount of sulfhydryl groups in those two kinds of systems. The effect of sulfhydryl groups on the fading of tartrazine and sunset yellow was verified by testing the fading rate at different concentration of cysteine systems. Results The results showed that the artificial color was more stable than β-carotene in a non-milksystem, but in milk beverage the artificial color showed a faster fading rate compared to β-carotene. The results of Ellman＇s method indicated that the whey protein isolate contained more sulfhydryl groups than sodium caseinate, leading to a faster fading rate of the artificial color in whey protein isolate-containing beverages. The higher the concentration of L（＋）-cysteine, the faster the artificial color faded. Conclusion It showed that the number of sulfhydryl groups was one of the main reasons for the fading of tartrazine and sunset yellow in milk beverage.