Development of a probiotic delivery system based on gelation of water-in-oil emulsions

- Gellan gels presented prevalence of elastic behavior 7 min after acidification.
- Spherical microbeads with diameter of 1.85 μm were produced by emulsion gelation.
- Survival rate to in vitro digestion of encapsulated L. rhamnosus was higher than 77%.

The protection and delivery of probiotic cultures remain a challenge for the food industry. In this work, a new delivery system was developed based on gellan added to the aqueous phase of a water-in-oil emulsion. The concentration of polysaccharide was evaluated to control gel mechanical properties. Uniaxial compression tests were performed to characterize the mechanical properties of gels, and rheological oscillatory tests were conducted to evaluate gelation time. Different emulsion formulations were evaluated with the aim of producing small microgels. The resistance of microgels to digestion steps was evaluated by size measurements and ζ-potential analyses in in vitro tests. The microgels were stable to oral and gastric digestion, but they were destabilized in enteric fluid. Lactobacillus rhamnosus was encapsulated into the gelled and non-gelled emulsions, and its survival was evaluated after in vitro digestion. The probiotic viability was higher than 77% in gelled emulsion and decreased to 66% when the aqueous phase did not form gel. Our results show that emulsion gelation improved microbial resistance to in vitro digestion conditions.