奶制品.应用连续pH测定法对奶制品培养菌的酸化活性测定

[中文适用范围]： 本国际标准规定了一种通过连续测量pH值来测定乳酸菌酸化活性的方法。该方法适用于含有这些特征微生物的乳制品发酵剂。程序中指定了两种类型的标准化牛奶：干物质质量分数为9.5%的煮沸牛奶（B-牛奶9.5）；以及干物质质量分数为9.5%的灭菌牛奶（A-牛奶9.5）。B-牛奶9.5的热处理可能无法灭活所有存在的酶，这可能会影响某些发酵剂的活性。在这种情况下，发酵剂应使用A-牛奶9.5进行测试，因为A-牛奶9.5中所有酶均已灭活。 [外文原描述]： ISO 26323|IDF 213:2009 specifies a method for the measurement of the acidification activity of lactic acid bacteria by continuous measurement of pH. The method is applicable to dairy starter cultures where these characteristic microorganisms are present. Two types of standardized milk are specified in the procedure: boiled milk with 9,5 % mass fraction dry matter (B-milk 9,5); and autoclaved milk with 9,5 % mass fraction dry matter (A-milk 9,5). It is possible that heat treatment of B-milk 9,5 does not inactivate all enzymes that are present, which can affect the activity of some cultures. In that case, cultures are tested with A-milk 9,5 in which all enzymes have been inactivated.