Optimization of the storage conditions of freeze-dried lactic acid bacteria for the design of probiotic products for raniculture.

S.E. PASTERIS; G. MONTEL MENDOZA; M.C. OTERO; M.E. NADER-MACÍAS

Estambul

Simposio; 23rd International ICFMH Symposium, FoodMicro2012; 2012

The bullfrog (Lithobates catesbeianus) products are of main interest in the global market: the meat has a high degree of absorbable proteins and low fat contents, and thus desirable for dyslipidemic patients; the liver is used for “pâté” elaboration. These aspects require intensive farming operations, increasing the risk of infectious diseases outbreaks by causing mass mortality and a high impact on the production costs. In previous works, lactic acid bacteria (LAB) from Argentinean bullfrog hatcheries were isolated and selected as potentially candidates to design probiotic products to prevent epizootics in raniculture. The protective effect of probiotics depends on the number of viable bacterial cells, which is related to the preservation method, the freeze-drying process being the most frequent method to maintain the viability and functional properties of beneficial bacteria. In this work, the effect of storage conditions (drying medium, temperature and time) on the viability and beneficial properties (production of inhibitory metabolites, hydrophobicity and autoaggregation) of indigenous Lactococcus lactis CRL 1584 and CRL 1827; Lactococcus garvieae CRL 1828 and Lactobacillus plantarum CRL 1606, was evaluated. Bacterial cells were dried in skim milk, whey protein concentrate (WPC), sucrose, lactose, (individually and combined), later included in glycogelatin capsules, and stored in plastic bottles with silica gel at 4 and 25°C during 12 months. A full three-factor ANOVA test was applied to each strain. The results show that the number of viable cells at 4°C were significantly higher (p≤0.05) than at 25°C. Moreover, the ANOVA tests for LAB strains indicated that the decrease of cell viability within the time was significant. The optimal drying media for CRL 1827 and CRL 1828 strains was 5% skim milk+5% lactose; for CRL 1606 was 5% skim milk+5% sucrose, while for CRL 1584 were 5% WPC+5% lactose and 5% skim milk+5% lactose. In all the experiment, the beneficial properties of the rehydrated LAB strains were not affected. This study allows the selection of the optimal conditions for the long storage of LAB strains to formulate a probiotic product to be used during bullfrog breeding.