Viability of Lactobacillus acidophilus La5 in pectin–whey protein microparticles during exposure to simulated gastrointestinal conditions

Abstract

The objective of this study was to evaluate whether the coating of pectin microparticles containing Lactobacillus acidophilus La5 with whey protein heat treated or without heat treatment affects the viability of probiotics when exposed to conditions simulating the passage through the gastrointestinal tract. The microparticles were produced by ionotropic gelation and coated with whey protein by electrostatic interaction. The microparticle morphology and the viability of L. acidophilus La5 during exposure to simulated gastric (pH1.2 or 3.0) and intestinal (pH7.0) conditions were evaluated. There was no significant difference in the viability of L. acidophilus La5 after encapsulation, which was in the order of 8 log10 CFU/g for all the microparticles. The pectin microparticles remained intact when exposed to simulated gastrointestinal conditions at pH1.2, 3.0 and after 300min at pH7.0. On the other hand, both microparticles coated with whey protein heat treated or without heat treatment have remained intact for 120min exposure to simulated gastric juice but have disintegrated after 300min exposure to simulated intestinal juice (pH7.0). This occurrence suggests that the probiotics would be released in a different part of the intestinal tract whether delivered by one microparticle or another. Microencapsulation conferred greater protective effect to L. acidophilus as compared to the free cells. However, the coating of pectin microparticles with whey protein did not confer additional protection to probiotics when exposed to simulated gastrointestinal conditions.