通过比较不同贮藏温度(4、20和37℃)条件下不同pH值(pH 4.9组和pH6.7组)的牡蛎蛋白饮料在杀菌及贮藏期间褐变指数、游离氨基酸、总糖和还原糖浓度以及pH值的变化,初步探讨饮料中色泽形成的机理,为牡蛎蛋白饮料加工提供科学理论依据.试验结果显示,两组饮料的褐变指数在杀菌及贮藏过程中均有明显的上升趋势,但是pH6.7组的褐变指数总体明显高于pH4.9组,另外褐变指数总体与贮藏温度呈正相关.成分分析结果显示,两组饮料在贮藏过程中成分变化的规律基本一致,但是pH6.7组各成分变化的幅度较pH4.9组大.其中,天门冬氨酸等部分氨基酸呈明显上升趋势,而精氨酸、苏氨酸、丝氨酸、半胱氨酸、酪氨酸等氨基酸以及还原糖呈明显下降趋势.从以上结果可以推测,精氨酸、苏氨酸、丝氨酸、半胱氨酸和酪氨酸等氨基酸以及还原糖是牡蛎饮料非酶褐变反应的主要因子,温度和pH是牡蛎饮料发生褐变反应的重要条件,高温和高pH值可以促进牡蛎饮料褐变反应的发生.%In this investigation,beverages were prepared in two pH conditions(pH 4. 9 and pH 6. 7) and stored in three temperature conditions (4,20 and 37 ℃), and the mechanism of color formation was preliminarily discussed, by determination of browning index, pH value, free amino acids, total sugar and reducing sugar content,in the step of sterilization and during storage. The results showed the browning index in pH 6. 7 groups was higher than that of pH 4. 9 groups not only during the sterilization but during the storage,in which temperature promoted the browning action as a whole. Composition analysis showed that both groups of beverage were similar in change of compositions, but the pH 6. 7 group was more violent than that of pH 4.9 group. The kinds of amino acids and their concentrations became fluctuant during storage,in which, some amino acids such as aspartic acid increased remarkably, while some amino acids such as threonine, serine, cystein, tyrosine and arginine decreased evidently. On the other hand, the concentrations of total sugar and reducing sugar were decreased obviously during storage. These results imply amino acids such as threonine, serine, cystein, tyrosine, arginine, and reducing sugar involved the browning reaction whose distribution to be a Maillard reaction, and consequently causing the beverage color down during processing and storage, where both pH value and storage temperature were the major influencing conditions.
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