Techniques de séchage des starters lactiques et mécanismes affectant la viabilité cellulaire suite à la lyophilisation

Abstract

Preservation of industrial's lactic acid bacteria (probiotics) by freeze-drying. Majority of the lactic acid bacteria have important nutritional needs and do not have resistance against the environmental conditions surrounding their production (drying, storage, etc.) and their use in vivo (physico-chemical properties of the digestive tract). In this condition, industrialists and microbiologists develop regularly research projects of new lactic bacteria able to support the whole of the processes of production, storage and formulation without losing their functional properties. Among the various methods of drying (atomization, fluidization and freeze-drying), freeze-drying makes it possible to obtain a thorough dehydration compatible with very long storage times. This method involves changes in product temperature and is enough aggressive for microorganisms because they require freezing that is not without consequences for cells. In other cases, it causes cellular (peroxydation of the fatty-acids) and genetic (modification of proteins) deteriorations. The use of cryoprotecteurs during freeze-drying and of antioxidants during storage appreciably increases the rate of viability of these cells.

Keywords

• Probiotics
• freeze-drying
• cellular fatty acid
• free radicals
• hydroperoxides
• peroxydation
• cryoprotectants