Double encapsulation of Lactobacillus casei in carriers based on alginate-carboxymethyl cellulose and whey protein and its antimicrobial effect on Listeria monocytogenes and Escherichia coli.

Abstract

Abstract: Aim: Double emulsion microcapsules (W1/O/W2) containing probiotic bacteria Lactobacillus casei and carrying alginate and whey protein are designed to protect against stomach acid conditions and increase survival after entering the intestine. Material and methods: In this study, we showed the role of double emulsion W1/O/W2 with alginate-whey system (0.5, 1, 3, 5% w/v) on liquid digestive digestibility of Lactobacillus casei strain. PGPR was used as a lipophilic surfactant in the oil phase containing soybean oil. The emulsion structure was studied by (FTIR) and X-ray diffraction (XRD). Morphological properties were also investigated. In addition, in vitro release of probiotics was evaluated by pH changes. Then, the antimicrobial properties of microencapsulated probiotics were investigated in the milk environment after exposure to microbial agents such as Escherichia coli and Listeria monocytogenes. Results: Based on the obtained results, the survival of encapsulated Lactobacillus casei increased with increasing whey percentage. So that the highest survival rate is related to the sample of 5% whey. Also, the alginate-whey system is stabilized in the simulated gastric fluid and ensures better protection of the probiotics enclosed in the acidic environment. On the contrary, they swell in simulated intestinal fluid and help release the encapsulated probiotics. The responsiveness of the alginate-whey system to their acidic pH to protect probiotics in simulated gastric fluids as well as the release of probiotics in simulated intestinal fluids indicates potential application for targeted delivery of probiotics to the intestine. Also, due to the production of bacteriocin by probiotics, it can be concluded that they can have favorable antimicrobial properties against microbial agents such as Escherichia coli and Listeria monocytogenes, but in the present study, due to the microencapsulation of the probiotic, there was little change in the number of microorganisms. It was not observed and was not statistically significant (p>0.05). Conclusion: The results were that encapsulating probiotic strain liquid with double emulsion system is desirable in oral applications. Also, the antimicrobial effect of encapsulated Lactobacillus casei on the pathogenic agents of Escherichia coli and Listeria monocytogenes was investigated. Key words: Lactic acid bacteria, alginate, whey protein, probiotics