Abstract: Probiotics offer numerous health benefits for human beings. However, it is difficult to achieve the expected beneficial effects of oral probiotics due to the viability loss during processing, storage and digestion. Oral delivery systems are effective ways to improve the processing and storage stability, gastric acid and bile salt tolerance, and intestinal adhesion and colonization ability of probiotics. This review focuses on the state of the art of oral delivery of probiotics, and summarizes the types of probiotics commonly used in probiotic products and their functional characteristics. Specifically, this review analyzes the effects of external environmental factors such as humidity, temperature, pH and oxygen, and internal environments such as the mouth, stomach, and small intestine on the survival rate of probiotics. Furthermore, the characteristics and applications of different oral delivery systems including microcapsule, hydrogel, oleogel, nanocoating, emulsion, and nanofiber are compared. Finally, this review proposes future prospects for cost reduction, intelligent packaging, co-packaging and population experiments of probiotic delivery systems, with the aim of providing technical support for the development of probiotic formulations with high storage stability and high viability suitable for intestinal targeted delivery.

Key words: probiotics, encapsulation, delivery system, microcapsule, viable count, intestinal colonization