热处理对汉麻乳稳定性的影响及蛋白结构表征

为研究热处理对汉麻乳稳定性及其蛋白结构的影响，本实验通过汉麻乳氮溶解指数、离心沉淀率、乳化特性、乳液表面电位和粒径等指标监测汉麻乳热处理过程中稳定性的变化，利用傅里叶变换红外光谱表征热处理对汉麻乳蛋白二级结构的影响。结果表明：随着热处理温度的升高（55～95 ℃），汉麻乳氮溶解指数由58.55%逐渐减小到39.81%，离心沉淀率由16.58%逐渐增加到34%，汉麻乳蛋白的平均粒径由192.2 nm逐渐增大到304.6 nm；傅里叶变换红外光谱分析结果显示，随着热处理温度的升高，汉麻乳蛋白分子二级结构发生变化，α-螺旋结构相对含量由28.57%减少到23.70%，无规卷曲结构的相对含量由21.13%增加至25.41%；汉麻乳在65 ℃热处理时，Zeta电位绝对值达到最大（20.57 mV），此时汉麻乳表现最稳定，乳化活性及乳化稳定性最高，乳化活性指数为0.357 m2/g、乳化稳定性指数为43.74%。本研究结果将为汉麻乳加工及应用提供理论依据。

Effect of Heat Treatment on the Stability of Hemp Seed Milk and Characterization of Protein Structure

The purpose of this study was to investigate the effect of heat treatment on the stability and protein structure of hemp seed milk. The stability was monitored by the nitrogen solubility index (NSI), centrifugal precipitation rate, emulsification characteristics, emulsion surface potential and particle size. Fourier transform infrared (FTIR) spectroscopy was used to characterize the secondary structure of hemp seed milk proteins. The results showed that with the increase in heat treatment temperature (55–95 ℃), the NSI decreased from 58.55% to 39.81%, the centrifugal precipitation rate increased from 16.58% to 34%, and the average particle size increased from 192.2 nm to 304.6 nm. The results of FTIR analysis showed that the secondary structures of hemp seed milk proteins changed with the increase in heat treatment temperature. The relative content of α-helix decreased from 28.57% to 23.70%, while the relative content of random coil increased from 21.13% to 25.41%. The maximum absolute value of zeta potential of 20.57 mV was observed when hemp seed milk was treated at 65 ℃, accompanied by the best stability and the highest emulsification activity and emulsification stability with emulsifying activity index (EAI) of 0.357 m2/g and emulsion stability index (ESI) of 43.74%. This study will provide a theoretical basis for the processing and application of hemp seed milk.