Application of whey protein micro-bead coatings for enhanced strength and probiotic protection during fruit juice storage and gastric incubation

CONTEXT: Coated whey protein micro-beads may improve probiotic protection and provide delayed cell-release mechanisms. OBJECTIVE: Lactobacillus rhamnosus GG was encapsulated in whey protein micro-beads by droplet extrusion with coating via electrostatic deposition: primary-polysaccharide and secondary-whey protein. MATERIALS AND METHODS: Storage studies were performed in cranberry and pomegranate juice (pH 2.4; 28 days; 4 and 25°C) followed by simulated ex vivo porcine gastric (pH 1.6) and intestinal (pH 6.6) digestion. RESULTS AND DISCUSSION: After storage and simulated gastro-intestinal digestion, free cells, cells suspended in protein and cells encapsulated in alginate micro-beads, illustrated complete probiotic mortality, while coated micro-beads enhanced probiotic viability after juice storage (8.6 ± 0.1 log(10)CFUmL(-1)). Beads also showed significant binding of hydrophobic molecules. Coated micro-beads illustrated high gastric survival (9.5 ± 0.1 log(10)CFUmL(-1)) with 30 min delayed intestinal release relative to non-coated micro-beads. CONCLUSIONS: Micro-bead coatings could be applied in delayed cell-release for targeted intestinal probiotic delivery.