Encapsulation is a common approach to improve the bacterial survival of probiotics. In this study, two new low-methoxyl pectins (CMP-6 and CMP-8) were used as coating materials to produce microcapsules (MCs) for the encapsulation of Lactobacillus acidophilus LMG9433T, Lactobacillus casei LMG6904T, and Lactobacillus rhamnosus LMG25859. A fermentation test showed that encapsulation did not influence the fermentation ability of lactobacilli. The biofilm formation of encapsulated lactobacilli was stimulated when an in situ cultivation was conducted on MCs, which was verified by cryo-SEM observation. The resultant biofilm-forming MCs (BMCs) contained high-density bacterial cells (∼1010 CFU/mL). Compared to planktonic lactobacilli, pectin-based MCs showed significant protection for encapsulated lactobacilli from heat shock and simulated gastric digestion. Especially, benefiting from the biofilm formation, BMCs provided higher protection with enhanced resistance to heat shock, freeze-drying, and gastrointestinal digestion than MCs. Our result highlighted the superior bacterial resistances of biofilm-forming probiotics encapsulated in pectinate microcapsules.
Keywords: Lactobacillus; biofilm; encapsulation; heat shock; low-methoxyl pectin.