The effects of microcapsules with different protein matrixes on the viability of probiotics during spray drying, gastrointestinal digestion, thermal treatment, and storage

The objective of this research was to encapsulate probiotic bacteria based on the protein matrix and investigate the influences on the survival of probiotic bacteria during spray drying, in vitro gastrointestinal digestion, heating, and storage. A probiotic isolate Bacillus coagulans BC01 was spray dried in whey protein isolate (WPI), soy protein isolate (SPI), camel whey protein isolate, or sodium caseinate. Probiotic microcapsules fabricated using WPI obtained the highest survival during spray drying, NaCl and paraxin challenges and storage, as less cell wall damage occurred during spray drying which could be observed by flow cytometer. However, the highest survivals during in vitro gastrointestinal digestion and thermal treatment were found in microcapsules with SPI matrix, which could be attributed to its relatively low solubility in water that prevented probiotics from being released prematurely, thus protecting probiotics from the damage of low pH environment and diminishing the direct contact of cells with external heat shock. In conclusion, the current study demonstrated that WPI-based probiotic microcapsules with less cell wall damage during processing and SPI-based probiotic microcapsules with relatively low solubility may provide better protection to adverse external environments.