富含α-亚麻酸的中长链脂肪酸结构脂的 酶法合成与理化性质分析Enzymatic synthesis and physicochemical properties of medium- and long-chain triacylglycerols rich in α-linolenic acid

Abstract

旨在为富含多不饱和脂肪酸（PUFA）的中长链脂肪酸甘油三酯（MLCT）产品的应用提供参考，采用脂肪酶Lipozyme TL IM催化精炼桑蚕蛹油（SPO）与三辛酸甘油酯（TRI）进行酯交换反应合成富含α-亚麻酸（ALA）的MLCT（ALA-MLCT），考察了反应时间对ALA-MLCT合成的影响，并对合成的ALA-MLCT的甘油三酯组成、质量指标、氧化稳定性、乳液性能和体外消化特性进行了分析。结果表明：Lipozyme TL IM催化效率高，反应10 h TRI的转化率达到98%以上，反应12 h合成的产物ALA-MLCT中含有ALA的MLCT含量可以达到40.41%，且主要为LnCaCa (1095%)、PLnCa (7.69%)和OLnCa (6.21%)，其质量指标符合中长链脂肪酸食用油标准征求意见稿2022中的一级食用油标准；与SPO和酯交换反应底物物理混合物（SPO与TRI质量比1∶ 4,SPO+TRI）相比，产物ALA-MLCT氧化稳定性显著提高，其乳液粒径较小且分布均匀，具有更好的物理稳定性；体外模拟消化实验表明，与SPO+TRI相比，ALA-MLCT更快达到消化平衡，但最终二者消化率均可以达到90%以上。综上，合成的ALA-MLCT结构脂有助于提高ALA的生物可及性，有望作为功能性食用油脂。In order to provide reference for the application of medium-and long-chain fatty acid triglycerides (MLCT) products enriched with polyunsaturated fatty acids (PUFA), lipase Lipozyme TL IM was employed to catalyze the transesterification of refined silkworm pupa oil (SPO) and tricaprylin (TRI) to synthesize MLCT rich in α-linolenic acid (ALA) (ALA-MLCT). The impact of reaction time on the synthesis of ALA-MLCT was studied, and the triglycerides composition, quality index, oxidative stability, emulsion performance, and in vitro digestion characteristics of the ALA-MLCT were analyzed. The results showed that Lipozyme TL IM had high catalytic efficiency, and the conversion rate of TRI reached more than 98% after 10 h of reaction. The content of MLCT containing ALA in ALA-MLCT synthesized by transesterification reaction for 12 h reached 40.41%, and it was mainly composed of LnCaCa (10.95% ), PLnCa (769%) and OLnCa (6.21%). The quality indexes of ALA-MLCT complied with the standards of first-class edible oil in the medium- and long- chain fatty acid edible oil standard draft 2022. Compared with SPO and the physical mixture of transesterification reaction substrate (SPO+TRI, in a 1∶ 4 mass ratio), ALA-MLCT exhibited significantly improved oxidation stability, and its emulsion had better physical stability, with smaller and more evenly distributed particles size. In vitro simulated digestion experiments revealed that ALA-MLCT achieved a faster digestive balance compared with SPO+TRI, but the final digestibility of both could exceed 90%. In conclusion, the synthesized ALA-MLCT can help to improve the bioaccessibility of ALA and is expected to be used as functional edible oil.

Keywords

• 中长链脂肪酸结构脂；α-亚麻酸；酶法合成；氧化稳定性
• medium-and long-chain triacylglycerols; α-linolenic acid; enzymatic synthesis; oxidative stability