基于核桃油的中长链甘油三酯的酶法制备及纯化Lipase-catalyzed preparation of medium-and long-chain triglycerides based on walnut oil

利用脂肪酶催化中链甘油三酯（MCT）与核桃油发生酯交换反应，利用分子蒸馏脱除产物中的游离脂肪酸（FAA），再用乙醇萃取MCT制备高含量中长链甘油三酯（MLCT）的结构脂产品。对酶催化酯交换反应条件进行优化，对乙醇萃取条件进行优化，并对结构脂产品的脂肪酸组成及分布进行测定。结果表明：最佳酯交换反应条件为以Novozym 435为催化用酶，加酶量10%、MCT与核桃油摩尔比2∶ 1、反应温度55 ℃、反应时间9 h，在此条件下反应并通过分子蒸馏脱除FAA后所得产品的MLCT含量为76.2%，MCT含量为14.3%，长链甘油三酯（LCT）含量为9.5%；最佳乙醇萃取条件为乙醇体积分数85%、底物（分子蒸馏脱除游离脂肪酸后产物）与乙醇溶液的比例1∶ 3，在最佳条件下所得产品的MLCT含量为854%，MCT含量为3.7%，LCT含量为10.8%，产品得率为808%。制备的产品中MLCT含量高，富含亚油酸与亚麻酸，其含量比值为5.8，可作为消化系统缺陷患者补充必需脂肪酸的油脂来源。The product with high content of medium-and long-chain triglycerides (MLCT) was prepared by using lipase to catalyze the transesterification of medium-chain triglycerides (MCT) with walnut oil, using molecular distillation to remove the free fatty acid (FFA), and using ethanol to extract the MCT from the product. The enzyme-catalyzed transesterification reaction conditions and ethanol extraction conditions were optimized, and the fatty acid composition and distribution of the product were determined. The results showed that the optimal transesterification reaction conditions were obtained as follows: Novozym 435 dosage 10%, molar ratio of MCT to walnut oil 2∶ 1, reaction temperature 55 ℃ and reaction time 9 h. After reaction under these conditions and removal of FFA with molecular distillation, the contents of MLCT, MCT and long-chain triglycerides (LCT) were 76.2%, 14.3% and 9.5%, respectively. The optimal ethanol extraction conditions were obtained as follows: ethanol volume fraction 85%, and ratio of substrate (the transesterification product after molecular distillation) to ethanol solution 1∶ 3. Under these conditions, the contents of MLCT, MCT and LCT were 85.4%, 3.7% and 10.8%, respectively, and the product yield was 80.8%. This product with high content of MLCT was rich in linoleic acid and linolenic acid, and the content ratio of linoleic acid to linolenic acid was 5.8, which could be used as a source of oil to supplement essential fatty acids for patients with digestive system defects.