Abstract:

A combining method of freeze-drying with microencapsulation technology was used to improve the survival rate of Bifidobacterium lactis in the process of storage and consumption. With high efficient cryoprotectants and Bifidobacterium lactis as the core materials, Bifidobacterium lactis microcapsule was prepared by emulsification method. The varieties of cryoprotectant and their optimum ratio were optimized through orthogonal test, and the survival properties of freeze-dried Bifidobacterium lactis microcapsule in extreme environments such as simulated gastrointestinal environment and high osmotic environment were explored as well as the bile and acid tolerances. The results showed that the addition of 10% ilulin, 6% soy protein, 12% trehalose and 10% mannitol may significantly enhance the living bacterial number of microencapsulated Bifidobacterium lactis during freeze-drying and promote its survival rate to 69.2%. However, compared to the freeze-dried Bifidobacterium lactis powder, the freeze-dried Bifidobacterium lactis microcapsule presented better tolerance in simulated gastrointestinal fluid, high bile solution, high osmotic solution and acid food.

Key words: Bifidobacterium lactis, microcapsule, freeze-drying, cryoprotectant, tolerance