Guo Fengxian, Lin Luan, He Zhiyong, Zheng Zong-Ping
Fujian Province Key Laboratory for Development of Bioactive Material from Marine Alge College of Oceanology and Food Science Quanzhou Normal University Quanzhou Fujian China.
State Key Laboratory of Food Science and Technology Jiangnan University Wuxi Jiangsu China.
Food Sci Nutr. 2020 Aug 11;8(10):5275-5283. doi: 10.1002/fsn3.1759. eCollection 2020 Oct.
Soy protein is wildly used in food industry due to its high nutritional value and good functionalities. However, the poor storage stability of commercial soy protein products has puzzled both the producers and the users for a long time. The current study assessed the changes in protein solubility, aggregation, oxidation, and conformation of soy protein isolate (SPI) with various soluble aggregates formed at different pH values (pH 5-8) during storage. During storage, SPI samples showed a reduced protein solubility ( < .05), an increased protein oxidation ( < .05), and an attenuated conformational enthalpy (∆H). SPI with a higher pH produced more disulfide-mediated aggregates at the expense of sulfhydryl groups and experienced greater losses of protein tertiary structure and a faster reduction in solubility. Yet, all samples nearly shared similar rising trend during 8-week storage, which indicated the production of protein carbonyls was insensitive to pH. Soluble aggregates present in fresh SPI samples appeared to induce instability of SPI during storage. These findings suggested SPI prepared at pH 6 was in favor of its storage stability, and soluble aggregates presented in fresh samples should be paid more attention for further study of storage stability kinetics.
大豆蛋白因其高营养价值和良好的功能特性而在食品工业中广泛应用。然而，商业大豆蛋白产品较差的储存稳定性长期以来一直困扰着生产商和用户。当前研究评估了在储存过程中，大豆分离蛋白（SPI）在不同pH值（pH 5 - 8）下形成各种可溶性聚集体时，其蛋白质溶解度、聚集、氧化和构象的变化。在储存期间，SPI样品的蛋白质溶解度降低（<0.05），蛋白质氧化增加（<0.05），构象焓（∆H）减弱。较高pH值的SPI以巯基为代价产生更多二硫键介导的聚集体，并且蛋白质三级结构损失更大，溶解度下降更快。然而，在8周的储存期内，所有样品几乎都呈现出相似的上升趋势，这表明蛋白质羰基的产生对pH不敏感。新鲜SPI样品中存在的可溶性聚集体似乎会导致储存期间SPI的不稳定性。这些发现表明，在pH 6条件下制备的SPI有利于其储存稳定性，并且新鲜样品中存在的可溶性聚集体应在进一步研究储存稳定性动力学时给予更多关注。
