Preparation of Biofilm-State Bifidobacterium animalis Gr24 and Its Application in Probiotic Ice Cream

In order to solve the problem of low probiotic activity and poor application effect, the biofilm forming differences of Bifidobacterium animalis (B. animalis) Gr24 on five different carriers were evaluated. The optimal carrier was selected to determine the shaking culture conditions of B. animalis Gr24 biofilm, and its ability to resist freezing stress was analyzed, and the effects of biofilm-state B. animalis on the nutrient composition, physicochemical characteristics, storage characteristics, and probiotic properties of ice cream under shaking culture conditions were explored. The results showed that B. animalis Gr24 had the strongest biofilm-forming ability on pea hulls, and the optimal biofilm-forming time was shortened to 24 h. Freezing stress resistance analysis showed that biofilm-state B. animalis Gr24 under shaking culture conditions alleviated the damage of cell membranes and cell walls and the loss of ATPase activity, and the survival rate of the biofilm-state strains increased by 1.15 times compared with planktonic strains. The addition of shaking-cultured biofilm-state B. animalis Gr24 significantly reduced fat content and increased protein content of ice cream, improved product viscosity and hardness, and reduced expansion rate and melting rate, and stabilized probiotic viability, with a 1.5-fold increase in 18-week viable counts compared with planktonic strains. In addition, post-storage probiotic properties showed that low temperature storage significantly improved gastrointestinal environment resistance, intestinal epithelial cell adhesion and antioxidant activity of shaking-cultured biofilm-state strains. In conclusion, the shaking culture conditions significantly improved the biofilm-forming efficiency and the freezing stress resistance of B. animalis Gr24, which could ensure the good quality characteristics of the ice cream while improving its functional activity. This study aimed to lay the industrial technological foundation for the further development of highly resistant probiotic foods.