高纯度单月桂酸甘油酯的酶催化合成

Enzymatic Synthesis of Glycerol Monolaurate with High Purity

采用脂肪酶Novozyme 435催化月桂酸甲酯与甘油进行酯交换反应制备单月桂酸甘油酯。以反应体系中单月桂酸甘油酯的质量分数为考察指标,通过单因素实验和正交实验对酶催化合成工艺进行优化,得到最佳的工艺条件为:底物摩尔比n(月桂酸甲酯)∶n(甘油)=1∶5,底物质量分数为20%(即月桂酸甲酯与叔丁醇的质量百分数,下同),反应温度为55℃,酶添加量为7%(即酶与月桂酸甲酯的质量百分数,下同),初始含水量为20%(以月桂酸甲酯质量计,下同),转速为100 r/min,反应时间为1 h,在该条件下,体系中单月桂酸甘油酯的质量分数为71.86%。经提纯后终产物中单月桂酸甘油酯的质量分数高于95%,最高可达98.76%,而双月桂酸甘油酯的质量分数低于5%。酶重复使用6次,单月桂酸甘油酯的质量分数从71.75%降至68.36%,其催化性能无显著降低。

Glycerol monolaurate（ GML） was obtained by transesterification between methyl laurate and glycerol using a lipase（ Novozyme 435） as a biocatalyst. The effects of enzymatic synthesis process were optimized by single-factor and orthogonal experiments using the mass fraction of glycerol monolaurate in the reaction system as an examing index. The results show that the optimum conditions are as follows： substrate molar ratio 1 ∶ 5,substrate mass fraction 20%,reaction temperature 55 ℃,enzyme amount 7%,water content 20%,rotational speed 100 r / min and reaction time 1 h. The mass fraction of GML in the reaction system was 71. 86% under the above mentioned condition. After purification of the final product,the mass fraction of GML was higher than 95%,its maximum reached98. 76%,while that of glycerol dilaurate（ GDL） was less than 5%. When Novozyme 435 was recycled for 6 times,the mass fraction of GML decreased from 71. 75% to 68. 36%,which indicated that the catalytic performance of Novozyme 435 had no obviously decrease.