CHARACTERIZATION AND IDENTIFICATION OF THERMOTOLERANT LACTIC ACID BACTERIA ISOLATED FROM COOKED SAUSAGES AS BIOPROTECTIVE CULTURES

ABSTRACT

Lactic acid bacteria (LAB) are employed in meat products preservation and fermentation. Some strains can survive thermal treatment in cooked meat products, where their bioprotective properties can be used to inhibiting other spoilage flora. A total of 68 presumptive LAB were isolated from commercial cooked sausages collected in Mexico City supermarkets. Based on biochemical tests, 22 strains were selected and their thermotolerant capacity and D_T values were determined in water baths. Only 10 strains were considered as thermotolerant after survive thermal treatments (70C at 30 min). Thermotolerant strains were identified by both phenotypic (API system) and genotypic (16S rRNA) analysis. The genera identified were Pediococcus, Lactobacillus, Aerococcus and Enterococcus. Differences in phenotypic and genotypic in some strains were found, because of a close phylogenetic proximity between the strains. Nonetheless, all the identified thermotolerant LAB strains are natural microflora of meat products and can be employed as bioprotective strains inoculating them before thermal processing in cooked meat products.

PRACTICAL APPLICATIONS

The isolation and identification of LAB strains as the native and dominant flora of meat and meat products could be useful in the looking of bacteria as bioprotective cultures, as LAB inhibit other spoilage and pathogen microorganisms. Thermotolerant capacity of these LAB isolated from cooked meat products is important as the application of these strains as starters during processing before thermal treatment ensures their role as dominant flora during storage. In addition, the potential probiotic of these thermotolerant LAB strains can be useful in functional cooked meat products manufacture.