B. GORANOV, D. BLAZHEVA, G. KOSTOV, Z. DENKOVA and Y. GERMANOVA
University of Food Technologies, BG – 4000 Plovdiv, Bulgaria
Goranov, B., D. Blazheva, G. Kostov, Z. Denkova and Y. Germanova, 2013. Lactic acid fermentation with encapsulated Lactobacillus casei ssp. rhamnosus ATCC 11979 (NBIMCC 1013) in alginate/ chitosan matrices. Bulg. J. Agric. Sci., Supplement 2, 19: 101–104
Microbial lactic acid production has been studied extensively. The interest in this process is ascribed to the wide application of lactic acid, as well as to the lactobacilli producing it. In the present work we investigated the lactic acid production by encapsulated Lactobacillus casei ssp. rhamnosus ATCC 11979 cells in alginate/chitosan complexes with solid and liquid core. Two different alginate forms – calcium and barium alginate – were studied, which provided different mechanical stability and survival rate of the microorganism. The lactic acid biosynthesis with immobilized cell was compared to a process conducted with free lactic acid bacteria. It was determined that both the free and the immobilized cells produced maximal lactic acid quantities when the active acidity level of the nutrient medium was pH 6.5. The free cells exhibited higher biosynthetic activity at cultivating temperature 37°C, while the immobilized cells had temperature optimum at 42°C. The immobilized preparations’ compressibility was determined, which depicted their mechanical stability. It was established, that the preparations with solid barium alginate core had the highest compressibility. The batch fermentation was carried out in a laboratory bioreactor with mechanical stirring. The dynamics of substrate uptake, accumulation of lactic acid, pH and redox potential of the fermentation medium were determined.