The exogenous protein (e.g. whey protein isolate, WPI) is commonly used to fortify and modify the functionality of starchy food, that might influence starch hydrolysis during gastric digestion. In this study, the effect of whey protein on the digestion of lotus seed starch (LS) subjected to a dynamic in vitro gastric digestion was investigated. The particle size distribution, the swelling power of the starch and the changes in pH, viscosity, microstructure and hydrolysis of 2% LS and blends of 2% LS with 1, 2 and 4% WPI were investigated. The presence of whey protein caused decreases in the particle size and the swelling power and an increase in the viscosity of the LS granules. The presence of whey protein also delayed the decrease in the pH and increased the hydrolysis of LS during the in vitro gastric digestion. WPI surrounded or encapsulated the LS granules observed using confocal laser scanning microscopy, and may have been the reason for the decrease in swelling power of the starch granules. The increased degree of gastric digestion of LS with the addition of WPI was largely related to the delayed decrease in the gastric pH rather than to alterations in the swelling power and viscosity and WPI’s physical barrier toward starch.

外源性蛋白质（例如乳清蛋白分离物，WPI）通常用于强化和改变淀粉类食物的功能，这可能会影响胃消化过程中的淀粉水解。在这项研究中，研究了乳清蛋白对经过动态体外胃消化的莲子淀粉 (LS) 消化的影响。研究了粒径分布、淀粉的溶胀能力以及 2% LS 和 2% LS 与 1、2 和 4% WPI 的混合物的 pH、粘度、微观结构和水解的变化。乳清蛋白的存在导致 LS 颗粒的粒径和溶胀能力降低以及粘度增加。在体外胃消化过程中，乳清蛋白的存在还延迟了 pH 值的降低并增加了 LS 的水解。WPI 包围或封装了使用共聚焦激光扫描显微镜观察到的 LS 颗粒，这可能是淀粉颗粒溶胀能力降低的原因。添加 WPI 后 LS 的胃消化程度增加在很大程度上与胃 pH 值的延迟降低有关，而不是与膨胀力和粘度以及 WPI 对淀粉的物理屏障的改变有关。