本研究利用胃液动态消化模型，探讨了大豆分离蛋白（SPI）乳液（O/W型和W/O型）在胃液酶解消化过程中酶解产物的特性。显微镜检和粒径测定发现，经酶解消化后，乳液液滴逐渐发生分离、絮凝和结合现象，O/W型液滴趋于逐渐变大，而W/O型液滴趋于逐渐变小。乳液经胃液酶解消化后，电位值均由胃液酶解前的负值变成正值，且O/W型电位值逐渐降低，W/O型电位值逐渐升高。说明强酸环境使乳液界面蛋白带电电荷残基发生变化，导致了乳液表面电荷的稳定失衡。两者的游离氨基酸含量都呈先升高后降低的趋势，小肽含量则是O/W型乳液先降低后升高，而W/O型乳液始终呈升高趋势，可推断，O/W型乳液在酶解消化过程中存在二次乳化现象，W/O型乳液没有。聚丙烯酰氨凝胶电泳（SDS-PAGE）和双向电泳分析乳液蛋白组分变化均表明，在胃液的酶解消化过程中，11S蛋白比7S蛋白更易酶解，且其在W/O型乳液中比O/W型乳液中酶解更快，β亚基不易酶解。双向电泳还表明，7S蛋白中偏碱性的亚基易酶解，11S蛋白中偏酸性的亚基易酶解。

The characteristics of the enzymatic hydrolysate of soybean protein isolate (SPI) emulsion (oil-in-water (O/W) and water-in-oil (W/O) type) in the process of gastric digestion were discussed by using the dynamic gastric model in this study. Microscopic examination and particle size determination showed that the uniformly distributed droplets were separated, flocculated, and combined gradually after being digested by the enzyme, and the liquid droplet size of O/W emulsion became larger, whereas that of the W/O emulsion became smaller. After the emulsion was digested by gastric juice, the potential values of emulsions changed from negative to positive; in addition, with the increase in the enzymatic hydrolysis time, the potential values of O/W emulsion and W/O emulsion gradually decreased and increased, respectively. This finding indicated that the strong acidic environment changed the charged protein residues at the emulsion interface, leading to an imbalance of the electric charges on the surface. The free amino acid contents of both emulsions and the content of small peptides of the O/W emulsion increased first and subsequently decreased, while the content of small peptides of W/O emulsion constantly increased. Therefore, it could be inferred that secondary emulsification occurred in the O/W emulsion but not in the W/O emulsion. Polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis were used to analyze the changes in the protein composition of the emulsions. The results showed that 11S protein was more easily hydrolyzed by pepsin than 7S protein during the enzymatic hydrolysis and was hydrolyzed faster in W/O emulsion than in O/W emulsion, while β subunit was not easily hydrolyzed. Furthermore, two-dimensional gel electrophoresis showed that the partial basic and the partial acidic subunits of 7S and 11S protein, respectively, were easily hydrolyzed by pepsin.

国家自然科学基金资助项目（31371782）；河南省教育厅科学技术研究重点项目基础研究计划（14A550007）；河南工业大学校基金基础研究重点培育计划（2013JCYJ04）