The objective of our study was to use of Lactobacillus bulgaricus and Streptococcus thermophilus for kinetics study of lactic acid production from Carob pods syrup and Date syrup. The biologic material used is cultures of Streptococcus thermophilus and Lactobacillus bulgaricus. The Lactic Acid Bacteria was isolated and identified by biochemical biochemical tests. Biochemical analysis of date and carob syrups was taken. Three cultures fermentations of Lactobacillus bulgaricus were carried out in a 2 L jar fermenter (Applikon Biocontroller ADI1030) in MRS broth, in date syrup at concentration 20% and in carob pods syrup medium at concentration 20%. The same cultures fermentations were made by Streptococcus thermophilus in Naylor and Sharpe medium, date syrup and carob pods syrup. The different physicochemical and biochemical analyzes show the richness of date and carob pods syrups in nutritional elements that makes them favorable to the lactic acid fermentations. The Lactobacillus bulgaricus and Streptococcus thermophilus growth’s for the fermentations are characterized by a short duration of the latency phase which indicates that the inoculated cells were in full exponential phase and the perfect adaptation of strains to the different medium used. Kinetics study of growth of Lactobacillus bulgaricus and Streptococcus thermophilus in Carob syrup and Date syrup showed that these medium are favourable to the lactic acid fermentations.
Ouis Nawel, Hariri Ahmed