Evaluation of Some Factors with Significant Influence on Functionality and Viability of Probiotic Strains LA-5 ® and L. Casei 431 ® in Multiple Starter Cultures in Mesophilic Fermented Milk

.  For a very long time, probiotics have been selected on the basis of their suitability to food’s environment and technological procedures, as well as survival ability in vitro and also in vivo. These criteria are still used. The aim of this study was to select, using the Plakett-Burman design of experiments model, of three significant factors, which influence the multiplication ability and viability of probiotic strains Lactobacillus acidophilus (commercial code LA-5®) and Lactobacillus casei subsp. paracasei (commercial code L. casei 431®) in fermented mesophilic milk product (commercial named Sana) obtained by fermentation with a multiple culture with mesophilic lactic starter Flora Danica Chr. Hansen commercial starters (Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. diacetylactis and Leuconostoc mesenteroides subsp. cremoris). By statistical analysis the most important factors (independent variables)  with influence on the probiotic bacteria were selected for the optimized. These are the temperature of fermentation; the ratio between probiotic strains and Flora Danica and the addition of prebiotic Fagopyrum esculentum flour. In the future experiments the optimum values of these parameters will be optimized by using response surface methodology, in order to establish the conditions in which can be obtain the mesophilic fermented milk products with probiotic action in vivo.