Impact of encapsulation of probiotics in oil-in-water high internal phase emulsions on their thermostability and gastrointestinal survival

Probiotics have many beneficial physiological effects, such as enhancing immunity and regulating intestinal microflora. However, the highly acidic conditions in the stomach and the high bile acid concentration in the small intestine pose challenges to the maintenance of probiotic activity after ingestion. In this study, we examined the possibility of increasing the viability of probiotics under gastrointestinal conditions by encapsulating them within oil-in-water high internal phase emulsions (HIPEs). These emulsions were prepared using whey protein isolate (WPI) and pectin, which were gelled by adding GDL and calcium to form double network HIPE gels. The gel strength, stability, and shear viscosity of the gelled HIPEs increased as the pectin concentration was raised from 0 to 2%. Cryo-SEM analysis showed that the pectin formed a dense hydrogel network in the aqueous phase surrounding the oil droplets in the HIPEs. Probiotics were encapsulated within the gelled HIPEs by dispersing a probiotic powder in the oil phase. Confocal microscopy indicated that the probiotics were mostly distributed in the water, and interfacial phases, with only a few of the probiotics remaining in the oil phase. Encapsulation of the probiotics in the HIPEs increased the number of live cells remaining after a heat treatment and after passage through a simulated gastrointestinal model. The incorporation of pectin into the HIPEs increased the viability of the probiotics, especially after exposure to the gastric phase. This study highlights the potential of HIPEs in preserving probiotic activity, which may be useful for the development of more effective functional foods.