Phytosteryls has been converted in high extent to the corresponding long-chain acyl esters via esterification with oleic acid or transesterification with methyl oleate or trioleoylglycerol using immobilized lipases Lipozyme IM and Novozym 435 as biocatalysts in vacuo 30 mbar and without adding water or solvent, at 80 ℃. This paper had investigated the effect of temperature, time and phytosterol dosage on conversion. By the response surface analysis, the optimum operating parameters of synthesis of phytosteryl esters by esterification and transesterification were as fol ows:reaction temperature of 80℃, vacuum of 30 mbar, reaction time of 48 h, enzyme dosage of 1.0%, phytosteryl dosage of 6.3%, the conversion rate was 97.65%. Transesterification of phytosteryls and fatty acid methyl ester using immobilized lipases Lipozyme IM as biocatalysts, lipases Lipozyme IM remained the conversion rate of more than 90%even after 10 times of repeated use. Lipase Novozym 435 remained the conversion rate of more than 40%.%使用固定化脂肪酶Lipozyme IM和Novozym 435作为催化剂,以转换率为指标,在真空度30 mbar、80℃、无溶剂和无添加水的反应条件下,探讨反应时间、酶添加量、甾醇添加量对酯交换生物合成甾醇酯的影响,通过响应面分析对固定化脂肪酶Lipozyme IM作为催化剂条件进行优化.最佳反应条件为:反应温度80℃、真空度30 mbar、反应时间48 h、酶添加量1.0%、甾醇添加量6.3%,转换率为97.65%.使用固定化脂肪酶Lipozyme IM作为催化剂条件下,甾醇与油酸甲酯进行酯交换,即使重复使用10次后仍保持90%以上转换率,脂肪酶Novozym 435仍保持40%以上转换率.
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