Study of fermentation growth kinetics and survival after freezing and lyophilization of microorganisms isolated from brazilian grape sourdough

This study was developed to evaluate the influence of strains of Lactobacillus paracasei (LP1 and LP2) and Saccharomyces cerevisiae (SC1 and SC2) in fermentation and in survival durin g the processes of freezing and lyophilization. The microorganisms were cultivated in a discontinuo us fermentation system for 15 h and the analyses of pH, absorbance, dry biomass and plate counts were p erformed. LP1 showed the same exponential phase as LP2, and its specific speed of growth was higher and statistical ly different from the others (P < 0.05). The yeasts presented growth rates higher than the LAB. However, the LAB presented higher biomass yields and lower pH values. LP2 showed the same exponential phase as LP1, its specific rate of growth was higher and statistically different from the others (P < 0.05). The microorganisms presented good stability before and after lyophilization, with LP2 showing l ower microbial reduction.