干热处理对米糠蛋白结构与功能特性的影响

对干热处理后米糠蛋白的结构及功能特性变化进行探讨，结果表明：90 ℃干热处理下米糠蛋白组分发生明显的热变性，米糠蛋白的β-折叠结构含量有较大程度降低，并主要转变为无规卷曲结构和β-转角结构。随着干热处理温度的升高，α-螺旋结构含量逐渐增大，无规卷曲结构和β-转角结构含量并未表现出明显的线性变化趋势。干热处理条件下无序结构的增多促进了米糠蛋白的水合作用，使米糠蛋白溶解性增加，而随着干热处理温度升高至100 ℃，米糠蛋白的溶解度有所降低；无序结构增多使米糠蛋白整体柔性增强，随着干热处理温度的升高，米糠蛋白的乳化性呈现先减小后增大的变化趋势，在100 ℃干热处理下米糠蛋白乳化性达到最大值45.56 m2/g，而米糠蛋白的乳化稳定性亦有所增加；米糠蛋白起泡性随干热处理温度的升高呈现先增大后减小的变化趋势，干热处理温度80 ℃时米糠蛋白起泡性达到最大值为87.36%，米糠蛋白的泡沫稳定性随干热处理温度升高逐渐降低。

Effect of Dry Heat Treatment on Structural and Functional Properties of Rice Bran Protein

The changes in structure and functional properties of rice bran protein caused by dry heat treatment were studied
in this research. Results showed that dry heat treatment at 90 ℃ caused obvious denaturation of rice bran protein, which
was manifested by a considerable decrease in β-sheet content and consequently an increase in random coil and β-turn
contents. The α-helix content increased gradually with an increase in heating temperature, while random coil structure and
β-sheet structure did not exhibit an obvious linear trend. The dry heat treatment resulted in the formation of more disordered
structures and promoted the hydration of rice bran protein, in turn improving its solubility. However, rice bran protein
became less soluble after undergoing dry heat treatment at 100 ℃. The overall flexibility of rice bran protein was enhanced
due to the formation of more disordered structures, and the emulsifying activity tended to decrease and then increase with
increasing temperature. Maximum emulsifying activity index (EAI) of 45.56 m2/g was obtained by dry heat treatment at
100 ℃, accompanied with an increase in emulsion stability. The foaming capacity of rice bran protein displayed an upward
and then downward trend with increasing temperature. Heat treatment at 80 ℃ gave maximum foam overrun of 87.36%, and
the foam stability was decreased by increasing temperature.