Survival of Weissella confusa and Lactobacillus paracasei strains in fermented milks under cold storage and after freeze-drying

The technological properties of two Lactobacillus paracasei (UI014 and UI022) and two Weissella confusa (UI006 and UI007) strains were studied in order to ascertain their suitability to be used in the formulation of probiotic fermented milks. All strains were able to grow in milk increasing their counts for more than 2 logarithmic units. Additionally, L. paracasei strains were able to acidify and coagulate the milk which indicates that they can be employed as starter cultures. However, W. confusa strains can only be used as adjunct cultures since their acidification rate was very low. The viability of most strains declined slowly during the cold storage of the dairy product and after 4 weeks, their counts remained approximately 10(7) cfu/ml. Thus, the shelf life of these dairy products is long enough to ensure the intake of viable cells that could promote health benefits. Finally, the four strains studied presented high survival after the freeze-drying process using skim milk as cryo-protectant. Thus this technology can be employed to supply these strains to the dairy industries to be used as starter or adjunct cultures for the formulation of probiotic foods.