大豆油和月桂酸制备MLM型结构脂质工艺优化及其性质分析

Optimized Preparation and Characterization of MLM-Type Structured Lipids from Soybean Oil and Lauric Acid

以大豆油和月桂酸作为反应底物,采用Lipozyme RM IM催化合成中长碳链(middle-long-middle,MLM)型结构脂质。通过响应面试验优化方法研究不同底物(月桂酸∶大豆油)物质的量比、反应温度、反应时间、脂肪酶添加量对合成结构脂质中月桂酸插入率的影响,并研究在最佳反应条件下MLM型结构脂质的理化性质。结果表明,最佳合成工艺条件下所得结构脂质的月桂酸插入率为29.26%,该条件为底物物质的量比6∶1、反应温度45℃、反应时间24 h、脂肪酶添加量为底物质量的13%。理化性质研究表明,与原大豆油相比,MLM型结构脂质碘值(97.38 g/100 g)、黏度(70.39 c P)均降低,皂化值(以KOH计)(229.58 mg/g)、结晶开始温度(4.89℃)和熔融开始温度(-19.87℃)均显著提高(P<0.05),而烟点(231.24℃)无显著差异(P>0.05)。本研究合成的MLM型结构脂质,提高了原大豆油的营养价值,为开发抗肥胖、降血脂的优质油脂提供理论依据。

MLM-type(medium-long-medium carbon chain)structured lipids were synthesized by the reaction between lauric acid(C12:0)and refined soybean oil using Lipozyme RM IM lipase as a catalyst.The effects of molar ratio of between soybean oil and lauric acid,reaction temperature,reaction time and lipase dosage on the insertion rate of lauric acid were studied.The physicochemical properties of the MLM-type structured lipids prepared under optimized reaction conditions were determined.The optimal conditions for the synthesis of MLM-type structured lipids were as follows:molar ratio of soybean oil to lauric acid 6:1,reaction temperature was 45℃,reaction time was 24 h,and enzyme/substrate ratio 13%.Under these conditions,the insertion rate of lauric acid was 29.26%.The iodine value(97.38 g/100 g)and viscosity(70.39 cP)of the structurzed lipids were lower than those of soybean oil,and the saponification value(calculated as KOH equivalent)(229.58 mg/g),crystallization starting temperature(4.89℃)and melting starting temperature(?19.87℃)were significantly higher than those of soybean oil(P<0.05),while no significant different(P>0.05)in smoke point(231.24℃)was found.The MLM-type structured lipids synthesized in this study had higher nutritional value than soybean oil and could be developed as anti-obesity and lipid-reducing high-quality oils.