该研究以低温脱脂豆粕为原料，采用“碱溶酸沉”法收集大豆蛋白沉淀，对其进行分散、热处理和喷雾干燥或冷冻干燥制备获得大豆分离蛋白（SPI）。通过观察该产品的热聚集行为及其所成热致凝胶机械性能，考察热处理和干燥方式对所得产品凝胶性能的影响。结果表明，热处理使制得大豆分离蛋白多以聚集体的形式存在，导致其溶解性（pH值7.0）分别从79.9%和69.8%下降至35.2%和42.0%。相对于经过热处理制得的大豆分离蛋白，未经过热处理制得的大豆分离蛋白其差示扫描量热仪分析图存在78 ℃和98 ℃吸热峰；其分散液再次经历热处理后，分散液中蛋白的体积分数约从30%下降至20%，展现出进一步聚集并形成有序结构的趋势；对于质量分数为16%的喷雾干燥大豆分离蛋白（SD-SPI）和冷冻干燥大豆分离蛋白（FD-SPI）样品分散液所制备的凝胶，其断裂应力分别为10.80 kPa和12.50 kPa，显著高于对应HSD-SPI（经热处理）凝胶的3.69 kPa和HFD-SPI（经热处理）的4.36 kPa，但后两者硬度高于前两者。另一方面，干燥方式没有对所得大豆分离蛋白的凝胶性质产生显著的影响。可见，大豆分离蛋白制备过程中对大豆蛋白分散液进行升温热处理是影响所得蛋白产品溶解性、聚集行为和凝胶性能的关键步骤。寻找相应的替代工艺有望提高大豆分离蛋白的品质和功能特性，拓展其在食品工业尤其是植物基食品中的应用。

Soy proteins, isolated from low-temperature de-fatted soy flakes via alkaline dissolution and acidic precipitation, were subjected to dispersion, heat treatment, and spray drying or freeze drying to prepare soy protein isolates (SPIs). The thermal aggregation behavior of the obtained products, as well as the mechanical properties of their gels, were observed to investigate the effects of heat treatment and different drying methods on the gelation properties of SPIs. The results indicate that heat treatment caused the SPIs to exist predominantly as aggregates. The solubility (at pH value 7.0) of the spray dried and freeze dried SPIs was reduced from 79.9% and 69.8% to 35.2% and 42.0%, respectively. Unlike SPIs prepared with heat treatment, the differential scanning calorimetry results of SPIs prepared without heat treatment showed heat absorption peaks at 78 ℃ and 98 ℃. After heating the dispersions again, the volume of the protein fraction in the dispersions decreased from 30% to 20%, showing a trend of further aggregation and the formation of ordered structures. The fracture stresses of gels prepared from spray dried-SPI and freeze dried-SPI sample dispersions with mass fractions of 16% were 10.80 kPa and 12.50 kPa, respectively, which are significantly higher than those of the heated spray dried-SPI (3.69 kPa) and heated freeze dried-SPI (4.36 kPa) gels. Nevertheless, the heated spray dried-SPI and heated freeze dried-SPI gels were harder than their unheated counterparts. In contrast, the drying methods did not have a significant impact on the solubility, thermal aggregation behavior, or gelation properties of the resultant SPI products. Therefore, the dispersion heat treatment used during SPI preparation is the key step that significantly affects the functional properties of SPI, including solubility, thermal aggregation behavior, and gelation properties. By seeking alternative solutions for heating during preparation, the quality and functional properties of SPIs could be improved. They could potentially be used as a functional ingredient in food processing, especially for plant-based foods.

广东省基础与应用基础研究基金项目（2022A1515010892）；河南工业大学小麦和玉米深加工国家工程研究中心开放课题资助课题（NL2021004）；广西重点研发计划项目（桂科AB22080014）