Osteopontin enhances the probiotic viability of Bifidobacteria in pectin-based microencapsulation subjected to in vitro infant gastrointestinal digestion

Encapsulation is usually adapted to improve probiotic viability under adverse environmental conditions, and used to ensure adequate amount of probiotics reach the distal gastrointestinal tract and achieve probiotic action. In the present study, sub-species of Bifidobacterium were encapsulated with pectin or alginate by an emulsification/internal gelation method. Bovine milk osteopontin (OPN) was used as an excipient with potential to improve the protection of the probiotics during processing and/or gastrointestinal digestion. Here, we reported that the use of OPN significantly improved probiotic viability during freeze drying and simulated infant gastrointestinal digestion. The viability of Bifidobacterium bifidum R0071 and Bifidobacterium breve M-16V loaded in pectin-based freeze-dried microcapsules with 0.5% OPN addition remained at over 106 CFU g−1 after simulated infant digestion. In comparison, the microcapsules without OPN had a probiotic viability of only 103 CFU g−1. The protective effect of OPN was proven to be dose dependent. For example, the B. bifidum R0071 viability was 6.1 log CFU·g−1 after the gastrointestinal digestion for the pectin-based microencapsulation without OPN addition, while the value remained at 8.4 log CFU·g−1 when OPN concentration reached 5%. In this study, we also demonstrated that extracellular calcium ions could chelate with OPN molecules which could be attributed to preventing damage of the probiotic cell wall and the improved protective effective of microencapsulation. Overall, these results provide new insight into the use of OPN as a microencapsulation excipient to promote probiotic viability and its potential future application in functional foods such as infant formula with enhanced gut health.