[Particular behavior of different Lactobacillus acidophilus strains in petit-suisse cheese].

The objective of this study was to evaluate the physico-chemical and microbiological characteristics of petit-suisse cheeses manufactured with the addition of two Lactobacillus acidophilus strains: LA-14 (potentially probiotic) and La-5 (probiotic culture), using Streptococcus thermophilus TA040 as starter culture. Three cheese-making trials were prepared: Q1 (control: with TA040), Q2 (with TA040 + LA-14), and Q3 (with TA040 + La-5). Parameters analyzed included microbial counts of probiotic, potentially probiotic and starter microorganisms, and physico-chemical parameters (pH and moisture) after 1, 7, 14, 21, and 28 days of storage of the product at 4 +/- 1 degree C. Viable counts of L. acidophilus remained between 7.46 and 7.62 log CFU g(-1) for La-5, and between 6.39 and 6.83 log CFU g(-1) for LA-14. As for the starter, higher populations were observed for Q2 (9.58-9.68 log CFU g(-1)) and Q3 (9.42-9.79 log CFU g(-1)), when compared to Q1, which suggests synergism between L. acidophilus and the starter culture. Moisture and pH values remained stable for cheeses Q1, Q2, and Q3, and no significant differences were detected between cheeses after the first day of storage (p > 0.05). Particular features of both L. acidophilus strains determined different behavior in petit-suisse cheese, and the better adaptation of the La-5 to the product environment was perceptible, since higher populations were observed when compared to LA-14.