【作者】 黄祥元；

【导师】 刘成国；

【作者基本信息】 湖南农业大学 ， 农产品加工及贮藏工程， 2009， 硕士

【摘要】 “乳糖不耐症”是影响我国乳业发展的瓶颈,而利用固定化β-D-半乳糖苷酶水解牛奶中的乳糖是解决“乳糖不耐症”的有效方法。本研究采用海藻酸钠和明胶协同包埋,利用CaCl₂溶液为胶凝剂制备颗粒微胶囊固定化β-D-半乳糖苷酶。系统研究了海藻酸钠浓度、明胶浓度和CaCl₂溶液浓度对固定化酶的结构性能及酶活力回收率的影响,得出海藻酸钠浓度在1.0%～1.5%变化、明胶浓度在0.8%～1.2%之间变化、CaCl₂浓度在3%～4%变化均能得到成型较好和固定化酶活回收率高的微胶囊。在上述研究的基础上,利用响应面法优化了固定化条件,结果表明:海藻酸钠的浓度为1.03%,明胶的浓度为1.03%,β-D-半乳糖苷酶浓度为0.3%时固定化酶活力回收率可以达到58.87%。对固定化β-D-半乳糖苷酶的酶学特性进行了研究,其最适温度和游离酶相差不大,但适应温度变得更宽,热稳定性也有所提高;最适pH值向碱性偏移,但pH值稳定性有所下降;动力学常数Km=1.604mmol/L相对于游离酶Km=0.1676mmol/L有所上升,说明和反应底物的亲和性有所下降;半衰期为6.25d,其生产能力约为每克固定化β-D-半乳糖苷酶能水解13.35 g乳糖。在连续操作搅拌式反应器中,表明固定化β-D-半乳糖苷酶适合低乳糖牛奶的生产。更多还原

【Abstract】 "Lactose intolerance" is the bottleneck of the dairy industry development in our country. To make use of immobilizedβ-D-galactosidase to hydrolyze lactose in milk can settle "Lactose intolerance" effectively.In this study, the enzyme was entrapped by sodium alginate, glutin and CaCl₂. The paper systematically studied the consistency of sodium alginate, glutin and CaCl₂ effecting the activity yield of immobilized enzyme and the diameter and the mechanism intensity of capsule, and the optional condition is that the consistency of sodium alginate, glutin and CaCl₂ respectively ranged 1.0% to 1.5%, 0.8% to 1.2% and 3% to 4%. From the above study, the optimum conditions selected by regression design were 1.03% sodium alginate, 1.03% glutin, 0.3% lactose. Finally the activity yield of immobilized enzyme was 58.87%.The properties of immobilizedβ-D-galactosidase were investigated. Compared to free enzyme the optional temperature didn’t change, but the applied temperature area changed larger and increased the hot stability; the pH adapted to alkalescence, but the pH stability was fell. The kinetics of immobilizedβ-D-galactosidase of Km=1.604mmol/L was higher than the free enzyme of Km=0.1676mmol/L, which indicated that the immobilizedβ-D-galactosidase’s appetency was fell. The half-life of immobilizedβ-D-galactosidase was 6.25 days. One gram immobilizedβ-D-galactosidase could hydrolyzed 13.35 gram lactose. The results showed that lactose was hydrolyzed effectively by the immobilizedβ-D-galactosidase.更多还原