INVESTIGATION OF SURVIVAL AND VIABILITY OF PROBIOTIC STRAINS DURING STORAGE
YORDANKA DERMENZHIEVA, VIKTORIA MARINOVA, ILIYANA RASHEVA,
YOANA KIZHEVA, PETIA HRISTOVA*
Department of General and Industrial Microbiology, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
*Corresponding author:pkabad@biofac.uni-sofia.bg
Keywords: probiotic products, lactic acid bacteria, transit tolerance, viability, storage
Abstract: Сorrect taxonomy identification, viability and transit tolerance of the probiotic strains are crucial for achievement of the expected effects of probiotic supplements. Probiotics strains may be incorporated in dietary supplements and other food matrices which are expected to have up to 24 months of stability. However, the viability of probiotic cultures depends on production technology, type of the product and storage conditions during the entire shelf-life. Survival of probiotic bacteria are also affected by the high concentration of digestive enzymes and the low value of pH, during their passing through the gastrointestinal system. To increase the transit tolerance of probiotic strains, capsule dosage form is often used. In the present study the survival of probiotic strains was monitored at different periods of the product storage. Also, the effect of pepsin and pancreatin on probiotic strains in various commercial formulations was tested. The impact of the capsule on the viability of probiotic strains in terms of storage has been studied. In vivo transit tolerance of the probiotic strains under simulated conditions was visualized by the fluorescence microscopy method. Our results showed that the strains tested were more sensitive to the simulated gastric juice conditions, and many of them did not survive after 90 minutes and were more resistant to small intestine conditions. Viability of the probiotic strains at pH 3 is higher than at pH 2. At pH 3 all strains in products showed similar stability, and their number only slightly decreased. It was observed that after 90 days of storage, the number of bacteria significantly decreased but was still in the order of 106 CFU/ml.