Abstract:This study aims to improve the encapsulation rate of Lactobacillus gasseri and enhance the colonization of the bacteria in human body.To be specific，the preparation process of the double-layer encapsulated L.gasseri microcapsules was optimized by response surface methodology.It was determined that the optimal preparation conditions were as follows：film formation time of 15 min，chitosan concentration of 0.6% ，and pH5.2.Under the optimal conditions，the encapsulation rate of L.gasseri was up to 76.52%.The yielded microcapsules were significantly more tolerant to the acid environment in human body，and all the bacterial cells were released in the simulated intestinal fluid within 1.0 h-1.5 h.Moreover，the storage stability of the microcapsules was significantly improved.