Irigoyen A, Izco J M, Ibáñez F C, Torre P
Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, Pamplona, Spain.
J Chromatogr A. 2000 Jun 9;881(1-2):59-67. doi: 10.1016/s0021-9673(99)01276-5.
Capillary electrophoresis was used to study the evolution of casein throughout the ripening process of Roncal Denomination of Origin ewe's milk cheese and to assess the type of rennet in its hydrolysis. Two manufactures were prepared, each with four vats; two of them had added lamb artisan rennet, batch A [clotting activity of 97.54 rennet units (RU) ml(-1)] and batch B [clotting activity of 16.26 RU ml(-1)]; one vat included calf industrial rennet, batch I (clotting activity of 45.70 RU ml(-1)); and the fourth vat had added mixed rennet, batch M, a 50:50 mixture of lamb (batch A) and calf (batch I) (clotting activity of 77.53 RU ml(-1)). The content of casein nitrogen in fractions alpha-casein1CE, alpha-casein2CE, beta-casein1CE and beta-casein2CE was quantified in cheese after 1, 15, 30, 60, 120 and 180 days of ripening. Beta-casein fractions undergo lesser degradation during the ripening time than alpha-casein proteins. The degradation of alpha-caseins is very much influenced by the clotting activity of the rennet used, so that the more active the clotting activity the greater the hydrolysis of those caseins. Nevertheless, it is at the level of beta-caseins that we observe the evidence of the influence of the type of rennet, thus noting a less intense proteolytic activity in the batch made with calf rennet, batch I.
采用毛细管电泳研究了原产地名称保护的Roncal母羊乳奶酪成熟过程中酪蛋白的演变，并评估了凝乳酶在其水解过程中的类型。制备了两种产品，每种产品有四个发酵罐；其中两个添加了羔羊手工凝乳酶，A批次[凝乳活性为97.54凝乳酶单位（RU）ml⁻¹]和B批次[凝乳活性为16.26 RU ml⁻¹]；一个发酵罐添加了小牛工业凝乳酶，I批次（凝乳活性为45.70 RU ml⁻¹）；第四个发酵罐添加了混合凝乳酶，M批次，羔羊（A批次）和小牛（I批次）各占50:50的混合物（凝乳活性为77.53 RU ml⁻¹）。在成熟1、15、30、60、120和180天后，对奶酪中α-酪蛋白1CE、α-酪蛋白2CE、β-酪蛋白1CE和β-酪蛋白2CE组分中的酪蛋白氮含量进行了定量。在成熟过程中，β-酪蛋白组分的降解程度低于α-酪蛋白。α-酪蛋白的降解受所用凝乳酶凝乳活性的影响很大，因此凝乳活性越高，这些酪蛋白的水解程度越大。然而，正是在β-酪蛋白水平上，我们观察到了凝乳酶类型影响的证据，因此注意到用小牛凝乳酶I批次制作的产品中蛋白水解活性较弱。
