Enhanced viability of probiotics (Pediococcus pentosaceus Li05) by encapsulation in microgels doped with inorganic nanoparticles

The major reduction in probiotic viability that occurs during food storage and gastrointestinal transit limits their potential health benefits. Microencapsulation is one of the most effective methods to protect probiotics from various harsh conditions. In this study, a model probiotic (Pediococcus pentosaceus Li05) was encapsulated in an alginate-gelatin microgels in the absence and presence of magnesium oxide (MgO) nanoparticles (NPs). The morphology and surface properties of the encapsulation systems were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), which showed that both the probiotics and NPs were successfully incorporated into spherical microgels. The viability of the probiotic was evaluated after exposure to different conditions: long-term storage in an aerobic environment; heat treatment; and gastrointestinal transit. Encapsulation of the probiotics significantly enhanced their viability under these different conditions. Probiotics encapsulated in MgO-loaded microgels were more stable than free bacterial cells or those encapsulated in microgels alone: less than 2 log(10) CFU reduction after 40 min incubation in gastric fluids versus 5 log(10) CFU reduction in the first 10 min for free cells. The SEM images indicated that the NPs may lead to enhanced probiotic viability by filling pores inside the microgels, which may have inhibited the ability of oxygen and hydrogen ions to access the probiotics. Moreover, the MgO NPs neutralized the hydrogen ions in the gastric fluids, thereby reducing acid-induced degradation of the probiotics. These results demonstrate that MgO-loaded microgels may be a promising encapsulation and delivery system for improving the efficacy of orally administered probiotics by protecting them from the harsh conditions during storage and in the gastrointestinal tract.