Abstract

In this study, casein was extracted from milk and hydrolyzed with pepsin at three different enzyme/substrate ratios (0.1:100, 0.15:100, and 0.2:100). Three molar ratios of casein or hydrolyzed caseing/gum Arabic (GA) (1:1, 1:2, and 2:1) were exposed to Millard reaction using wet heating method at 80 °C, 6 h. The conjugation of biopolymers through Millard reaction was verified by Fourier Transform Infrared (FT-IR), high performance size exclusion chromatography (HPSEC) and fluorescence spectrophotometry methods. Higher molecular weight was observed after the reaction experiment. Moreover, FT-IR spectrum showed changes in amide 1 and 2 bands and fluorescence spectrophotometry showed reduction of intrinsic fluorescence intensity. Maillard reaction got faster by increasing the degree of hydrolyzation and GA/hydrolyzed casein ratio. Conjugates with higher ratios of GA/casein showed more stable particle size distribution against freeze-thawing process. Increasing the degree of hydrolyzation did not affect significantly on particle size distribution of conjugates. Functional properties of conjugated biopolymers including solubility, emulsifying and foaming properties were promoted compared to casein and casein/GA mixture. Also, hydrolyzed casein-GA showed better emulsifying and foaming ability but less foaming stability than non-hydrolyzed samples.

摘要

在这项研究中，酪蛋白是从牛奶中提取的，并以三种不同的酶/底物比例（0.1:100、0.15:100 和 0.2:100）用胃蛋白酶水解。酪蛋白或水解酪蛋白/阿拉伯树胶 (GA) 的三种摩尔比（1:1、1:2 和 2:1）在 80 °C 下使用湿加热法进行 Millard 反应 6 小时。通过傅里叶变换红外 (FT-IR)、高效尺寸排阻色谱 (HPSEC) 和荧光分光光度法验证了通过 Millard 反应进行的生物聚合物的结合。反应实验后观察到更高的分子量。此外，FT-IR 光谱显示酰胺 1 和 2 波段发生变化，荧光分光光度法显示固有荧光强度降低。通过增加水解程度和 GA/水解酪蛋白比率，美拉德反应变得更快。GA/酪蛋白比例较高的缀合物显示出抗冻融过程更稳定的粒径分布。增加水解度对缀合物的粒度分布没有显着影响。与酪蛋白和酪蛋白/GA 混合物相比，共轭生物聚合物的功能特性（包括溶解性、乳化性和发泡性）得到提升。此外，水解的酪蛋白-GA 显示出更好的乳化和发泡能力，但发泡稳定性低于未水解的样品。与酪蛋白和酪蛋白/GA 混合物相比，乳化和发泡性能得到提升。此外，水解的酪蛋白-GA 显示出更好的乳化和发泡能力，但发泡稳定性低于未水解的样品。与酪蛋白和酪蛋白/GA 混合物相比，乳化和发泡性能得到提升。此外，水解的酪蛋白-GA 显示出更好的乳化和发泡能力，但发泡稳定性低于未水解的样品。