乳清分离蛋白-甜菜果胶共价复合物理化特性分析

Physicochemical Properties of Whey Protein Isolate-Beet Pectin Conjugate

摘要:

蛋白质-多糖通过Maillard反应生成共价复合物，其乳化稳定性等功能特性得到提高，为研究与开发新型食品添加剂提供了一条新的途径，但共价复合物的乳化稳定性提高机理尚不明确。本研究通过界面张力仪测定界面张力、红外光谱分析二级结构，并结合GPC-动态光散射法考察其分子量分布，初步探讨乳清分离蛋白（WPI）-甜菜果胶（BP）共价复合物乳化稳定提高原因。研究结果表明：WPI-BP共价复合物与混合物相比，界面张力降低；WPI-BP共价复合作用使得蛋白质分子中的羟基含量增加，亲水性增强；共价复合物的分子量增大，dn/dc降低，分子量分布更集中，提高其在乳状液界面上的空间位阻作用，从而提高其乳化稳定性。因此，界面张力降低、亲水性增强与空间位阻增大是WPI-BP共价复合物乳化稳定性提高的主要原因。

Abstract:

The protein-polysaccharide conjugate via Maillard reaction showed improved emulsification property, which can be served as new mutifunctional food additives. To make clear of the mechanism, the interfacial tension, secondary structure and molecular weight distribution of whey protein isolate (WPI)- beet pectin (BP) mixture and conjugate were studied by the interfacial tensionmeter, FTIR and GPC-dynamic light scattering, respectively. Compared with mixture, WPI-BP conjugate showed lower interfacial tension and an increase in hydrogen bonds of the secondary structure. A higher molecular weight and more homogeneous distribution of the conjugate were also observed by the analysis of GPC-dynamic light scattering. Therefore, the improved emulsification property of WPI-BP conjugate might be due to the decreased interfacial tension, increased hydrogen bonds and steric hindrance.