Effect of protein-based nanoencapsulation on viability of probiotic bacteria under hostile conditions

The present study aimed to evaluate the effect of the incorporation of protein-based nanoencapsulation on the viability and stability of probiotic Lactobacillus rhamnosus in digestion conditions and model food. In the study’s first phase, protein-based nanoparticles were prepared by the pH cycling method, and then the probiotic, Lactobacillus rhamnosus, was nano-encapsulated. Two types of proteins, namely, whey protein and zein protein, were used to encapsulate probiotics individually. The obtained nano-encapsulated probiotics were characterized by performing particle size, SEM, FTIR, and in vitro assay was performed. Then, free and nano-encapsulated probiotics were added to the model food (yogurt) and analyzed for microbiological and sensory evaluation. Nanoencapsulation with both types of proteins significantly (p < .05) improved the stability and viability of Lactobacillus rhamnosus. The particle size for whey and zein nano-encapsulated probiotics ranged between 96 and 100 nm. The encapsulation efficiency for whey and zein nanoparticles was recorded at 96% and 87%, respectively. SEM images for both zein and whey nanoparticles showed their irregular spherical structure. FTIR spectra suggested that the mechanism of entrapment involved in water-insoluble or physical properties was mostly responsible for the generated loaded nanoparticle. In vitro analysis illustrated that whey nanoencapsulation showed the highest viability in SGC and SIC, followed by zein nanoencapsulation and free probiotics showed the minimum viability. Protein nanoencapsulation also significantly affected the sensory properties of food products. Conclusively, the nanoencapsulation of probiotics using protein nanoparticles helps prolong the viability and stability of probiotics under-simulated gastrointestinal digestion conditions and in yogurt.