Preparation and properties of biofilm-states Bifidobacterium adolensentis Gr19 under dynamic culture system and its application on probiotic ice cream manufacture

Biofilms are microbial aggregates that attach to the surfaces of specific substances, producing extracellular polymeric substances (EPS) to increase their resistance. However, the biofilm-state strains produced by the current static culture system are not industrially applicable. Therefore, this study aimed to establish a dynamic culture system to investigate the biofilm-forming ability of Bifidobacterium adolensentis (B. adolensentis) Gr19 on pea hulls, wheat bran, flaxseed bran, buckwheat bran, and quinoa bran (2% w/v), and analyze the effect of different culture systems on the probiotic properties of bacterial strains. Finally, the probiotic activity, physicochemical properties, stability, and sensory acceptability of ice cream supplemented with dynamically cultured biofilm-state strains were evaluated. B. adolensentis Gr19 formed the most biofilms on flaxseed bran in the dynamic culture system. It showed better cell adhesion ability and resistance to bile salts, gastrointestinal fluids, and low temperatures than planktonic-state strains. Adding dynamically cultured biofilm-state strains to ice cream significantly improved product hardness, reduced overruns and melting rates, and stabilized probiotic viability, yielding 6.1 log CFU/mL viable bacteria after 18 weeks of storage. Although the sensory score of ice cream decreased due to a sandy texture, no significant changes were evident in consumer purchase patterns. The results indicated that by-products could be used to establish a dynamic culture system for biofilm strains. This might offer a theoretical basis for creating highly resistant probiotics for the food industry and reduce the possibility of contamination in the agro-industry.