β-半乳糖苷酶的固定化及其在制备低乳糖牛奶中的应用

Immobilization of β-Galactosidase and Its Use in Preparing Low Lactose Milk

利用海藻酸钠和壳聚糖两种固定化载体对三种β-半乳糖苷酶(Maxilact酶、Lactozym酶和来源于米曲霉的β-半乳糖苷酶)进行固定化,研究温度和p H对酶活力的影响,游离酶和固定化酶水解牛奶中乳糖制备低乳糖牛奶,以及固定化酶的重复利用性。结果表明:与游离酶相比较,固定化酶在最适反应温度、最适反应p H、乳糖水解和重复利用性方面均有提高,表现出良好的稳定性。相比之下,壳聚糖固定化酶比海藻酸钠固定化酶的效果好,其中壳聚糖固定化Maxilact酶效果更为突出,该酶的最适反应温度为60℃,最适反应p H为7.0,在相同加酶量的条件下水解牛奶2 h后,乳糖水解率达99.93%,重复利用5次后,乳糖水解率仍能达到99.28%,重复利用性高,可以减少成本。此次研究为利用固定化酶工业化生产低乳糖牛奶奠定了一定的基础。

Three kinds of β-galactosidase（Maxilact, Lactozym and β-galactosidase from Aspergillus oryzae） were immobilized using sodium alginate and chitosan. The following studies were performed on the influence of temperature and pH on the enzyme activity, use of free enzyme and immobilized enzyme in hydrolysis of lactose in milk for preparation of low lactose milk and reuse of immobilized enzyme. The results showed that compared with free enzyme, immobilized enzyme showed improved optimal reaction temperature, optimal reaction pH, lactose hydrolysis and reuse, and showed good stability. Chitosan immobilized enzyme, by contrast, was found to be better than sodium alginate immobilized enzyme. Chitosan immobilizing Maxilact was more outstanding, the optimal temperature of Maxilact was 60 ℃, the optimum pH was 7.0, the lactose hydrolysis rate in milk was 99.93% under the same conditions after 2 h, and after 5 times reuse, and the lactose hydrolysis rate was 99.28%. Due to these reasons, the cost in industries can be reduced. This study lays a foundation for using immobilized enzyme to produce low lactose milk.