以乳极性脂/蛋白为界面脂滴的体外消化特性研究

Study on in vitro digestion characteristics of milk polar lipid/protein as interface lipid droplets

探究脂滴的界面组成对消化特性的影响,可为开发具有极性脂界面的脂滴提供理论依据。从酪乳粉中提取并浓缩制得乳极性脂浓缩物(MPL),以MPL和酪蛋白酸钠(CN)为乳化剂制备具有不同界面组成的脂滴,基于婴儿体外胃肠道消化模型分析了两者的体外消化特性。结果表明:与以CN为界面的脂滴相比,以MPL为界面的脂滴在消化过程中具有较高的脂肪酸释放量,且脂解率较高;由消化过程中粒径的变化可知,MPL组脂滴在消化过程中产生了更多的小颗粒脂滴,表明更多的大颗粒脂滴被水解;Zeta-电位的变化表明MPL组脂滴在消化过程中具有较好的稳定性,有利于消化反应的进行;在消化终点时,MPL组较CN组脂滴释放更多的游离棕榈酸、油酸单甘酯和亚油酸单甘酯。综上可知,以MPL为界面的脂滴在模拟婴儿消化过程中具有较好的消化特性。

This work mainly explores the influence of the interface composition of lipid droplets on the digestive properties,and provides a theoretical basis for the development of lipid droplets with polar lipid interfaces.In this work,total lipids were extracted from buttermilk powder,and then milk polar lipid concentrate(MPL)was extracted by acetone concentration,The content of polar lipids in the concentrate was 30.5% measured by ^(31)P-NMR.MPL and sodium caseinate(CN)were uniformly dispersed in phosphate buffer(water phase),respectively.Then,the oil phase was mixed with the water phase at a ratio of 8%(m/m),and after shearing,lipid droplets with the same particle size but different interface compositions were obtained.Based on an infant in vitro gastrointestinal digestion model,the mean particle size,Zeta-potential,free fatty acid release,glyceride composition and fatty acid composition at the end of digestion of lipid droplets during digestion were analyzed.In this way,the effect of different interfaces of lipid droplets on digestive properties was explored.The results showed that compared with lipid droplets with CN as interface,lipid droplets with MPL as interface had a higher release of fatty acids during digestion.The TAG content of lipid droplets with CN as interface was 11.22% at the end of digestion,while the TAG content of lipid droplets with MPL as interface was 8.15%,indicating that lipid droplets with MPL as interface had a higher lipolysis rate.From the change of particle size during the digestion process,the lipid droplets in the MPL group produced more small lipid droplets during the digestion process,indicating that more large lipid droplets were hydrolyzed.Zeta-potential results showed that the potential values of lipid droplets with MPL as interface during digestion were lower than those with CN as interface,indicating that lipid droplets in the MPL group had a strong electrostatic repulsion and good stability during digestion,which is conducive to the digestion reaction.At the end of digestion,the lipid droplet with MPL released more free palmitic acids,monoolein and monolinolein than that with CN.