Effect of pectic oligosaccharide on probiotic survival and physicochemical properties of hydrogel beads for synbiotic encapsulation of Lactobacillus bulgaricus

The present study was carried out to evaluate the effects of different concentrations of pectic oligosaccharide (POS) on the physicochemical properties of Lactobacillus bulgaricus (L. bulgaricus) loaded-synbiotic hydrogel beads and the survival of L. bulgaricus. Low methoxyl (LM) pectin-resistant starch (RS) hydrogel beads, named RS beads, were coated/filled with different concentrations of POS: 0.8% (RS-POS0.8 beads), 1.0% (RS-POS1.0 beads), and 1.2% (RS-POS1.2 beads). POS treatment resulted in smooth beads with less surface dent by hydrogen bonding between RS beads and POS, which was confirmed by SEM and XRD analyses. The encapsulation efficiency of RS beads and RS-POS beads ranged from 90.40% to 92.03%. In simulated gastric fluid (SGF) and bile salt solution, free L. bulgaricus completely died but L. bulgaricus encapsulated in RS-POS1.2 beads only slightly decreased. This indicates that RS-POS1.2 beads exhibited higher protective effects on L. bulgaricus under SGF condition and bile salts. Furthermore, considering the relatively higher storage stability of L. bulgaricus loaded in RS-POS1.2 beads, the present results suggest that RS beads coated/filled with POS could be used for synbiotic encapsulation, protection, and delivery of probiotics.