Institute for Animal Production System in Mediterranean Environment, National Research Council, Via Argine, 1085, 80147 Naples, Italy.
Institute for Animal Production System in Mediterranean Environment, National Research Council, Via Argine, 1085, 80147 Naples, Italy.
Food Chem. 2017 Apr 15;221:1637-1641. doi: 10.1016/j.foodchem.2016.10.125. Epub 2016 Oct 29.
The shelf life of milk and its products is strongly influenced by the quality of raw milk. Several bacteria present in raw milk can produce proteases: among them, those from psychotropic microorganisms (e.g. Bacillus subtilis), which produce enzymes under refrigeration, cause the most serious problem. The interaction of these enzymes with the milk proteins and the main proteolytic enzymes becomes important in determining the quality of the milk. An artificial substrate (azocasein) was used to quantify the enzyme activity through the release of a chromogenic product that was measured spectrophotometrically after clarifying the sample by the addition of trichloroacetic acid. The detection limit and quantification limit were 1.43 and 4.77mg/ml respectively for sheep milk and, 2.25 and 7.5mg/ml respectively for goat milk. This method is useful for determining the proteolytic activity in different media and its effectiveness depends on chemical-nutritional characteristics of the sample.
牛奶及其制品的保质期受原料奶质量的强烈影响。生奶中存在的几种细菌可以产生蛋白酶：其中，那些来自精神类微生物（如枯草芽孢杆菌）的蛋白酶在冷藏下产生，会造成最严重的问题。这些酶与牛奶蛋白和主要蛋白酶的相互作用在决定牛奶质量方面非常重要。通过释放显色产物来定量酶活性，使用人工底物（偶氮酪蛋白），在添加三氯乙酸澄清样品后，通过分光光度法进行测量。羊奶的检测限和定量限分别为 1.43 和 4.77mg/ml，山羊奶的检测限和定量限分别为 2.25 和 7.5mg/ml。该方法可用于测定不同介质中的蛋白水解活性，其有效性取决于样品的化学-营养特性。
