自由基接枝改性对乳清分离蛋白乳化稳定性的影响

林佳宜; 郑佳纯; 李雁; 解新安; 李璐

doi:10.13386/j.issn1002-0306.2021110006

自由基接枝改性对乳清分离蛋白乳化稳定性的影响

Effect of Radical Graft Modification on Emulsifying Stability of Whey Protein Isolate

摘要

摘要: 为研究蛋白的共价接枝改性对其乳化稳定性的影响，本文以乳清分离蛋白（whey protein isolate，WPI）和表没食子儿茶素没食子酸酯（epigallocatechingallate，EGCG）为原料，通过自由基接枝法制备WPI-EGCG复合物。利用扫描电镜（SEM）对其微观结构进行观测，通过测定界面蛋白吸附量、界面流变学特性来探究共价接枝对界面特性的影响；进而以WPI-EGCG接枝物为乳化剂构建番茄红素纳米乳液，并对其物理化学稳定性及储藏稳定性进行研究。结果表明，EGCG的自由基接枝改变了WPI的结构，使之具有更高的黏度和界面稳定性，使以接枝物为乳化剂的番茄红素纳米乳液体系具有更高的物化稳定性。WPI-EGCGE接枝物稳定的番茄红素纳米乳液在37 ℃下储藏30 d后粒径和ζ-电位绝对值分别增加了268.3 nm和17.6 mV，乳液中番茄红素的保留率仍有66.23%，呈现出更佳的番茄红素保护效果。本研究为功能活性物质纳米乳液载运体系的构建提供了参考。

Abstract: In order to understand the effect of covalent graft modification of protein on its emulsifying stability, WPI-EGCG graft was prepared by free radical grafting using whey protein isolate (WPI) and epigallocatechingallate (EGCG) as raw materials. Scanning electron microscopy (SEM) was used to observe the microstructure, and the effect of covalent grafting on the interface stability was investigated by measuring the adsorption capacity of interfacial protein and the rheological properties of the interface. Lycopene nano-emulsion was constructed by WPI-EGCG graft as emulsifier, and its physicochemical stability and storage stability were studied. The results showed that the free radical grafting of EGCG changed the structure of WPI and made it higher viscosity and interfacial stability, so that the lycopene nano-emulsion system using the graft as emulsifier had higher physical and chemical stability. The size and ζ-potential of the WPI-EGCGE graft-stabilized lycopene nano-emulsion increased 268.3 nm and 17.6 mV, respectively, after 30 days of storage at 37 ℃. The retention rate of lycopene in the emulsion was 66.23%, showing a better lycopene protection effect. This study would provide a reference for the construction of nano-emulsion transport system of functional active substances.