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本文研究共轭亚油酸异构体的分离方法。利用白地霉脂肪酶(Geotrichumcandidumlipase,GCL)催化合成正丁酯的方法,考察温度、体系水分、酶用量、反应时间、底物配比对脂肪酶催化酯化率和脂肪酸丁酯中c9t11含量的影响。结果表明,经过酯化的脂肪酸丁酯层中c9t11CLA含量达到79.85%,t10c12CLA含量为4.59%;含有13.75%的油酸;c9t11CLA占共轭亚油酸两种异构体总含量的94.56%。形成c9t11CLA正丁醇酯的选择性系数平均为17.80。脂肪酸与正丁醇比例对脂肪酸酯中c9t11CLA含量具有显著性影响,在选取的范围内水分含量、酶用量的影响不显著。要得到较高c9t11CLA含量的脂肪酸产物,反应因子应选择:水分为0.50%,脂肪酸与正丁醇用量比为2.00∶1.00,酶用量为100U/g。白地霉脂肪酶对催化c9t11共轭亚油酸与正丁醇的酯化反应具有较高的选择性,因此,脂肪酶选择性酯化分离CLA异构体的方法是可行的。
This article studies the separation of conjugated linoleic acid isomers. The method for the synthesis of n-butyl ester catalyzed by Geotrichum citandumum lipase (GCL) was used to investigate the influence of temperature, system moisture, enzyme dosage, reaction time and substrate ratio on the lipase-catalyzed esterification and the content of c9t11 in fatty acid butyl ester . The results showed that the content of c9t11CLA in the esterified fatty acid butyl ester layer reached 79.85%, the t10c12CLA content was 4.59%, the oleic acid contained 13.75%, and the c9t11CLA accounted for 94.56% of the total content of the two isomers of conjugated linoleic acid. The selectivity coefficient for formation of c9tllCLA n-butanol ester averaged 17.80. The ratio of fatty acid to n-butanol had a significant effect on the content of c9t11CLA in fatty acid esters. The influence of moisture content and enzyme dosage was insignificant in the selected range. To obtain higher c9t11CLA content of fatty acid products, the reaction factor should be selected: 0.50% moisture, fatty acid and n-butanol ratio of 2.00: 1.00, enzyme dosage of 100U / g. It is feasible that the lipase can catalyze the esterification reaction of c9t11 conjugated linoleic acid with n-butanol. Therefore, it is feasible to selectively esterify CLA isomers by lipase.