FREEZE DRYING OF BACTERIAL PREPARATIONS BASED ON LАCTOBACILLUS CASEI

Abstract

For the production of fermented food products, it is important to ensure efficient and long-term storage of microorganism cells of starter preparations. The problem of long-term storage of microorganisms is reduced to the creation of conditions for suspended animation, that is, inhibition of metabolic processes. Of the known methods for storing biomaterials, freeze drying or lyophilization (drying of the material under low pressure and at low temperatures) is considered one of the most effective and economical methods of long-term storage of microorganisms. During drying, cell survival depends on many factors, among which their biological characteristics associated with species and strain specificity, cultivation conditions, culture age, composition of the freeze drying medium, and technological parameters of this process occupy an important place. To protect microorganisms, protective media are used, into which substances are introduced that promote cell survival during freezing, drying and storage. The aim of this work: to select the components of a protective environment to stabilize the biomass of Lactobacillus casei (L. casei) with a high level of antagonistic action to technically harmful microflora and to establish storage regimes for the bacterial preparation. Subject of research: the ability of L. сasei lactobacilli to maintain viability and properties during freeze drying and storage. The work used commonly used microbiological and technological research methods. Research results. The protective effect of protective media on maintaining the viability of L. casei cells and the solubility of bacterial preparations was studied. The best performance was achieved when using sucrose-citrate and sucrose-gelatinous media in a ratio to cell biomass of 2: 1. Lyophilized bacterial preparations were produced, the quality indicators of which meet modern requirements: the number of cells at the level of (4.5-4.8) × 10 11 CFU / cm3, solubility - (0.4-0.5) cm3 of raw sediment and a sufficient level of activity in milk while maintaining a high antagonistic activity to E. coli, S. aureus and Bacillus cereus. When stored for six months at a temperature of (4 ± 2) C and 9 months at a temperature of minus (18 ± 2) C, bacterial preparations retained a high number of living cells and the ability to reactivate. Scope of research results application. The use of bacterial preparations with a protective effect against technically harmful microflora will improve the safety and quality of cheese.