响应面优化脂肪酶催化合成中长碳链甘三酯

采用响应面设计对脂肪酶Novozym 435在无溶剂体系中催化甘油和中长碳链脂肪酸(辛酸、癸酸和油酸混合物)酯化反应合成中长碳链甘三酯进行了研究.研究发现:反应温度、加酶量和反应时间对中长碳链甘三酯得率具有显著性影响(P＜0.05),而底物摩尔比(脂肪酸与甘油摩尔比)对中长碳链甘三酯得率不具有显著性影响.优化得到的最佳条件为:反应温度90℃,加酶量6.5％(以脂肪酸和甘油的总质量计),底物摩尔比3.5∶1,反应时间12.97 h.在此条件下,平均甘三酯得率为78.5％；产品中甘三酯、甘二酯、甘一酯和游离脂肪酸含量分别为85.6％、0.3％、0.1％和14.0％；产品甘三酯中辛酸、癸酸和长碳链脂肪酸含量分别为25.4％、10.7％和63.9％,与目标中长碳链甘三酯产品指标基本一致.

Optimization of lipase-catalyzed synthesis of medium- and long-chain triglycerides using response surface methodology

The medium-and long-chain triglycerides(MLCT) were synthesized from medium-and long-chain fatty acids(mixture of caprylic acid,capric acid and oleic acid) and glycerol by Novozym 435 lipase catalysis in a solvent-free system,and the reaction conditions were optimized by response surface methodology(RSM).The results showed that the reaction temperature,reaction time and enzyme load strongly affected MLCT yield(P<0.05),however,substrate molar ratio did not have a significant(P>0.05) effect on MLCT yield.The optimum conditions were as follows:reaction temperature 90℃,enzyme load 6.5%(rasis on the total mass of fatty acids and glycerol),substrate molar ratio(ratio of fatty acid to glycerol) 3.5∶1,and reaction time 12.97 h.The triglycerides yield was 78.5% under these conditions.The contents of triglycerides,diglycerides,monoglycerides and free fatty acids in the product were 85.6%,0.3%,0.1% and 14.0%,respectively.The fatty acids compositions of triglycerides were caprylic acid 25.4%,capric acid 10.7% and long-chain fatty acid 63.9%,which were almost in accordance with target product.