A study of the effect of free and encapsulated cells of the probiotic strain Weizmannia coagulans on the properties of a probiotic fermented milk product and an assessment of their survival under simulated gastrointestinal conditions

The creation of probiotic fermented milk products, additionally enriched with probiotics, capable of maintaining their viability during storage of the finished product and under the harsh conditions of the gastrointestinal tract (GIT) is a pressing issue. In this study, capsules of alginate, pectin, and κ-carrageenan, additionally coated with chitosan, were produced using an emulsion method, encapsulating cells of the probiotic strain Weizmannia coagulanS. Samples of the probiotic fermented milk product containing free and encapsulated W. coagulans cells were prepared, and the physicochemical, microbiological, and sensory characteristics of the finished product were analyzed. When testing the viability of the capsules in the finished product under simulated GIT conditions, it was found that encapsulated cells demonstrated a high survival rate compared to free cellS. For capsules made of an alginate-pectin mixture (A-P), it was 9.92 Log10 CFU/ml, for capsules made of an alginate-pectin-carrageenan mixture (A-P-C), 10.33 Log10 CFU/ml, the viability of free cells dropped to 2.17 Log10 CFU/ml. Encapsulated and free probiotic cells during storage of a fermented milk product had a significant impact on various characteristics of the finished product. A tendency towards an increase in titratable acidity, a decrease in viscosity, and an increase in syneresis was observed. The viability of free probiotic cells during 21 days of storage decreased by 7.13 Log10 CFU/ml, while the viability of encapsulated cells dropped by only 1.35 Log10 CFU/ml for A-P capsules and by 2.92 Log10 CFU/ml for A-P-C capsuleS. The addition of free and encapsulated cells had little effect on the sensory characteristics of the finished product at the end of its shelf life. The results showed that probiotic encapsulation significantly increased bacterial survival both in the finished product during storage and under simulated gastrointestinal conditions.