Microencapsulating role of whey protein isolate and sucrose in protecting the cell membrane and enhancing survival of probiotic lactobacilli strains during spray drying, storage, and simulated gastrointestinal passage

Limosilactobacillus reuteriKUB-AC5 andLactobacillus johnsoniiKUNN19-2 were spray-dried using whey protein isolate, sucrose, and whey protein isolate combined with sucrose at 130 °C and 150 °C. Differences in membrane fatty acid compositions of probiotics led to differences in cell membrane fluidity, cell injury, and cell survival during spray drying. Combination of whey protein isolate and sucrose improved survival of L. reuteriKUB-AC5, whose cell membrane were more fluid and more sensitive to stress, while whey protein isolate provided the best protection for L. johnsoniiKUNN19-2 against changes in protein secondary structures. Moreover, a relationship was found between membrane damage and the shelf-life ofmicrocapsules. Both microencapsulated cells prepared at the inlet temperature of 130 °C showed an enhanced survival upon simulated gastric digestion compared to the free cells. A thorough understanding of injury sites during spray drying will contribute to establishing optimal conditions and encapsulant formulations that maintain the cells' viability during spray drying, storage, and gastrointestinal passage.