Highly acid-sensitive Bifidobacterium adolescentis (ATCC 15703) cells were entrapped in pea, soy, faba, and lentil protein-alginate capsules and subjected to challenge studies in synthetic gastric juice (SGJ, pH 2.5/37oC) and intestinal fluids (SIF, pH 6.5/37oC). B. adolescentis cells trapped in pea, soy, faba, and lentil protein-alginate capsules showed 1.9, 3.3, 5.1, and 5.5 log reductions in cell numbers, respectively after a 2 h challenge. Release of encapsulated B. adolescentis cells in SIF over 3 h indicated that after the first 10 min, almost all cells were released, regardless of the wall material. Storage of pea protein-based capsules was also tested in commercial orange, pineapple, and white grape juices at 4 and 22oC for a 6-week duration. Encapsulated B. adolescentis cells survived in pineapple and white grape juice, but not in orange juice.
This study also evaluated survival of free and encapsulated B. adolescentis cells entrapped within PP-alginate capsules during storage in 3 types of fruit juice. Survival varied with the storage temperature and the type of fruit juice. After 6 weeks of storage, both free and encapsulated B. adolescentis cells entrapped in PP-alginate capsules survived in pineapple juice and white grape juice at 4 and 22oC. Entrapped cells probably exhibit greater survival rates upon encountering gastric conditions. Encapsulation using the PP-alginate system can be used for delivery of probiotics in beverages for optimization of health benefits.