Evaluation of the viability of a lactic acid bacteria at different encapsulation processes

Abstract

The aim of this study was to evaluate the effect of the microencapsulation process on the viability of Lactobacillus fermentum K73. The response surface methodology (RSM) was applied to design a culture medium (CM) with sweet whey and yeast extract in order to increase the production of biomass. The selected CM was used to hydrate the combinations between maltodextrin, sweet whey and / or gum arabic proposed by the mixtures experimental design. Cell viability and tolerance to in vitro gastrointestinal conditions were evaluated to obtain the optimal mixture. The CM and the optimal mixture were dried by spray-drying, freeze-drying and Refractance windowTM drying. The temperature was varied in the three drying technologies. The process conditions were determined by RSM (spray-drying and freeze-drying) and mathematical modelling (Refractance windowTM). The physicochemical properties and shelf life of the powder product were determinate. The viability of L. fermentum K73 were evaluated in a dynamic in vitro digestive system (IViDiS). The results showed that the optimized CM increased biomass production to 10.05 ± 0.39 Log10 CFU/mL. The cell viability was >8.90 Log10 CFU/g with the optimized mixture CM-maltodextrin-milk whey and >8.42 Log10 CFU/g with the CM as carrier material in the three drying technologies. The values of the physicochemical properties were within the normal range of a powder product. CM spray-dried was the powder that increased the viability of the microorganism during the shelf life and in IViDiS. Therefore, this study showed that the microencapsulation process of L. fermentum K73 with CM is a promising alternative for the manufacture of powder products stable over time and tolerant to gastrointestinal conditions.