酶解时间对大豆分离蛋白结构及功能性质的影响

Effect of Enzymatic Hydrolysis Duration on Structure and Functional Properties of Soybean Protein Isolate

为探究不同酶解时间下大豆分离蛋白酶解产物(soybean protein isolate enzymatic hydrolysate,SPIH)结构与功能特性之间的构效关系,通过测定不同酶解时间下的蛋白质水解度及多肽质量分数评估大豆分离蛋白(SPI)的水解情况;通过傅里叶变换红外光谱、内源荧光光谱检测和表面疏水性、乳化性及抗氧化能力测定,分析其结构与功能之间的关系。结果表明:SPI的水解度随酶解时间的延长不断增加,多肽质量分数随酶解时间的延长呈先增大后减小的趋势;其次,随着酶解时间的增加,蛋白质发生解折叠,酶解2 h时蛋白质结构逐渐舒展,最大吸收波长发生红移且荧光强度增强;此外,酶解使SPI二级结构发生了改变,酶解2 h时β-折叠面积分数最高。SPIH的表面疏水性、乳化性、抗氧化能力、ζ-电位及其乳液的粒径均在酶解2 h时呈现最佳状态。该研究为明确SPI在不同酶解时间下的结构与功能特性变化规律提供依据,拓宽其在食品行业的应用范围。

In order to investigate the structure-function relationship of soybean protein isolate enzymatic hydrolysate(SPIH)under different enzymatic hydrolysis time,the hydrolysis of soybean protein isolate(SPI)was evaluated by measuring the degree of hydrolysis and the mass fraction of polypeptide.The relationship between structure and function was characterized by Fourier transform infrared spectroscopy,endogenous fluorescence spectroscopy,surface hydrophobicity,emulsification,and antioxidant capacity.The results showed that the hydrolysis degree of SPI increased with the prolonged enzymatic hydrolysis duration,while the mass fraction of polypeptide initially increased and then decreased over the duration of enzymatic hydrolysis.Moreover,as the enzymatic hydrolysis time increased,protein unfolding occurred.The protein structure gradually unfolded after enzymatic hydrolysis at 2 h,leading to a red shift in maximum absorption wavelength and enhanced fluorescence intensity.In addition,the secondary structure of SPI was changed by enzymatic hydrolysis,with theβ-fold area fraction reaching its peak at 2 h.The surface hydrophobicity,emulsification,antioxidant capacity,ζ-potential and the particle size of the SPIH emulsion were all optimized at 2 h of enzymatic hydrolysis.This study provides the theoretical basis for understanding the changes in structural and functional properties of SPI under different enzymatic hydrolysis durations,thereby expanding its applications in the food industry.