响应面试验优化两步酶法合成母乳脂替代品工艺及脂肪酸组成分析

采用两步酶法合成母乳脂替代品。以油茶籽油和棕榈酸为原料,在有机相体系中利用脂肪酶Novozym 435催化合成Sn-2位富含棕榈酸的甘油三酯,通过单因素试验和响应面设计,获得了最佳合成条件为反应溶剂正己烷、溶剂用量10 m L/g、底物(棕榈酸-油茶籽油)质量比1.1∶1、脂肪酶用量(以底物质量计)10.1%、反应时间16.5 h、反应温度50℃,Sn-2位棕榈酸含量达到66.08%;以第一步酸解反应得到的甘油三酯和鱼油为底物,经Sn-1,3专一性脂肪酶Lipozyme TL IM催化酯交换制备母乳脂替代品。制品检测结果表明,其不仅棕榈酸的含量和分布与母乳脂相似,而且具有较高含量的二十碳五烯酸、二十二碳六烯酸等多不饱和脂肪酸,亦可作为婴儿配方奶粉的脂肪来源。

Optimization of Two-Step Lipase-Catalyzed Synthesis of Human Milk Fat Substitutes by Response Surface Methodology and Fatty Acid Composition Analysis

Human milk fat substitutes (HMFS) were prepared by a two-step enzymatic procedure. Firstly, triacylglycerols (TAGs) rich in palmitic acid (PA) at Sn-2 position were synthesized by Novozym 435 lipase-catalyzed acidolysis of camellia seed oil with palmitic acid in organic system. The optimal alcoholysis conditions were determined using one-factor-ata- time experiments and response surface methodology as follows: n-hexane as reaction solvent at a dosage of 10 mL/g; palmitic acid/camellia seed oil mass ratio, 1.1:1; lipase dosage (on the basis of substrate mass), 10.1%; reaction time, 16.5 h; and temperature, 50 ℃. Under these conditions, TAGs with 66.08% PA at Sn-2 position were obtained. Then HMFS were synthesized by transesterification of these TAGs with fish oil catalyzed by the Sn-1,3 specific lipase Lipozyme TL IM. The final product was tested, and the results showed that the content and distribution of palmitic acid in the HMFS were similar to those of human milk fat. Besides, it had high levels of eicosapentaenoic acid (EPA), and docosahexenoic acid (DHA). Therefore, the HMFS could be used as a fat source for infant formula.