Survival of probiotic bacteria in different types of preservation

The article presents the results of studies on the viability of probiotic bacteria during freezing and freeze drying. A consortium of probiotic bacteria was cultured on a nutrient medium with the addition of sodium Selenite at a concentration of 0.03 mg / ml to stimulate the synthesis of exopolysaccharides. Preservation of microorganisms was carried out when the stationary phase of development was reached. Centrifugation with a rotational speed of 3000 rpm for 25 minutes was used to concentrate the biomass. As a protective medium, a sterile 10% solution of saharosa with the addition of buffer salts was used. The biomass of bacteria was frozen at a temperature of minus (18-22) oC for two hours. Optimal lyophilization regimes were selected empirically: pressure 0.01-0.03 atm., temperature minus 50.3-51.2 oC, duration 28 hours. The mass fraction of moisture in the dried product is 2%. The survival rate of crops during drying is 76-85 % depending on the species.