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考察了脂肪酶催化合成葡萄糖硬脂酸酯(GSAE)的非水相转化条件及其效果。从7种商品化脂肪酶中筛选适于非水相酶法制备GSAE的酶,分别探讨脂肪酶种类及用量、助溶剂种类及用量、底物摩尔比、水分、分子筛用量、摇床速率、反应温度、反应时间等因素对GSAE合成反应产率的影响。结果表明,丙酮是适宜的助溶剂,在丙酮反应体系中固定化脂肪酶Novozyme 435是适宜GSAE酯化反应的最好催化剂,水分明显降低脂肪酶活性和酯化反应产率,底物、助溶剂和反应过程的除水对于该酯化反应是十分必要的。正交实验设计优化的酯化反应条件为:Novozyme 435酶用量0.08 g、分子筛用量0.8 g、n(硬脂酸)∶n(葡萄糖)=3∶1、反应温度45℃、丙酮用量10 mL、摇床转速150 r/min、反应时间5 h。该条件下最大反应速率Vm=0.749μmol/(min.g)和Km=0.020 3mmol/L,GSAE产率达64.11%。
The conditions of lipase-catalyzed non-aqueous phase conversion of glucose stearate (GSAE) and its effects were investigated. From seven kinds of commercial lipase, we selected the suitable enzymes for preparing GSAE by non-aqueous enzymatic method, and discussed the types and amount of lipase, the types and amount of solubilizer, the molar ratio of substrate, the content of water, the amount of molecular sieve, the rate of shaking, Temperature, reaction time and other factors on GSAE synthesis reaction yield. The results showed that acetone was a suitable cosolvent, and immobilized lipase Novozyme 435 was the best catalyst for GSAE esterification reaction in acetone reaction system. The water could obviously reduce the activity of lipase and the yield of esterification reaction. The substrate, cosolvent And the water removal of the reaction process is very necessary for the esterification reaction. The optimized esterification conditions of Novozyme 435 were as follows: 0.08 g of Novozyme 435, 0.8 g of molecular sieve, n (stearic acid): 3:1, reaction temperature 45 ℃, acetone 10 mL, Shaker speed 150 r / min, reaction time 5 h. Under this condition, the maximum reaction rate Vm = 0.749μmol / (min.g) and Km = 0.020 3mmol / L, the yield of GSAE reached 64.11%.