研究以棕榈油为酰基供体和L-抗坏血酸在有机相中利用脂肪酶催化酯交换反应合成L-抗坏血酸脂肪酸酯.对催化合成L-抗坏血酸脂肪酸酯的反应介质进行了比较,系统考察了底物浓度、溶剂用量、底物摩尔比、温度、水活度、分子筛加入时间和加入量对酶催化反应的影响,确定了最适反应条件:在20 mL用分子筛充分除水的叔戊醇中,0.352g·L-1抗坏血酸和4.535 g棕榈油(L-抗坏血酸和脂肪酸的底物摩尔比为1∶8)在14.2％(w/w,酶/L-抗坏血酸)的脂肪酶Novo435催化作用下,反应初始加入50 g·L-1的分子筛,温度55℃,摇床转速200 r ·min-1,反应24 h后底物转化率可达65％,产物浓度可达22 g·L-1.%The synthesis of L-ascorbyl fatty acid esters through transesterification of ascorbic acid and palm oil in tert-amy alcohol catalyzed by immobilized lipase was studied. A series of solvents used for the reaction were investigated, among them the tert-amyl alcohol was found to be the most suitable reaction media for the enzymatic synthesis of L-ascorbyl fatty acid esters. The addition of the molecular sieves was found to be helpful for reaction system to keep the water activity and to make the equilibrium go to the product. The factors affecting catalytic leaction, such as the substrate concentration, amount of solvent, substrate molar ratio, temperature, water activity and the addition of molecular sieve, were investigated. The results show that, when 0.352 g ascorbic acid and 4.535 g palm oil (the molar ratio of ascorbic acid to fatty acid is 1:8) are catalyzed by 14.2% Novo435 (weight % of ascorbic acid) in 20 mL terf-amyl alcohol with 50 g·L-1 molecular sieve added and rotation speed of 200 r·min-1, the conversion of ascorbic acid can reach 65% and the concentration of L-ascorbyl fatty acid esters is 22 g·L-1 after 24 h reaction at 55℃.
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