López-Fandiño R, Olano A, Corzo N, Ramos M
Instituto de Fermentaciones Industriales (CSIC), Madrid, España.
J Dairy Res. 1993 Aug;60(3):339-47. doi: 10.1017/s0022029900027680.
Proteolysis during storage of UHT skim and whole milks processed by either direct or indirect systems has been studied. All the proteolysis indices determined (measurement of free amino groups, PAGE of caseins and PAGE and reversed-phase HPLC of the fraction soluble at pH 4.6) revealed greater proteolytic degradation during storage of skim milks compared with that of whole milks subjected to the same UHT treatments. Increased activities of both native milk proteinase and proteinases of bacterial origin were observed in skim UHT milks. The different behaviour of UHT skim and whole milks on storage would have to be taken into account in establishing the process conditions.
对采用直接或间接系统加工的超高温灭菌脱脂奶和全脂奶在储存期间的蛋白水解情况进行了研究。所测定的所有蛋白水解指标（游离氨基的测定、酪蛋白的聚丙烯酰胺凝胶电泳以及pH 4.6时可溶级分的聚丙烯酰胺凝胶电泳和反相高效液相色谱）均显示，与经过相同超高温处理的全脂奶相比，脱脂奶在储存期间的蛋白水解降解更为严重。在超高温灭菌脱脂奶中观察到天然乳蛋白酶和细菌源蛋白酶的活性均有所增加。在确定加工条件时，必须考虑超高温灭菌脱脂奶和全脂奶在储存时的不同表现。
