Preparation of wheat germ albumin polypeptide microcapsules embedded with starch sodium octenylsuccinate/sodium alginate-based materials and sustained-release properties in vitro

The enzymatic hydrolysis products of wheat germ albumin have been extensively studied due to their strong antioxidant properties. The small intestine is an important part for absorbing active substances, but polypeptides are not acid-resistant and are easily hydrolyzed and lose their activity in the stomach, which does not achieve the effect of small intestine absorption. In this study, the optimal process conditions for microencapsulation of wheat germ albumin polypeptides were determined based on response surface optimization experiments as follows: wall to material ratio (starch sodium octenylsuccinate (SSOS): sodium alginate (SA) = 3:1), homogenization time 10 min, and wall to core ratio 20:1. The embedding rate of microcapsules prepared under these conditions was 65.33%. The average particle size of microcapsules was 100.21 μm. SEM results showed that the freeze-drying microcapsules had a sheet-like structure. The increased intensity of the amide A band in the microcapsules in Fourier transform infrared (FT-IR) spectroscopy indicated the formation of hydrogen bonds between the wall materials, while thermogravimetric analysis confirmed the protective effect of microcapsules on the formation of wheat germ albumin polypeptides. The release rates of microcapsules in gastric and intestinal juice were 26.54% and 84.41%, respectively, indicating that microcapsules had a sustained release effect. • The embedding rate of microcapsules prepared under the optimization conditions was 65.33%. • The average particle size of microcapsules was 100.21 μm. • Thermogravimetric analysis confirmed the protective effect of microcapsules on the formation of wheat germ albumin polypeptides. • The release rates of microcapsules in gastric and intestinal juice were 26.54% and 84.41%.