TECHNOLOGICAL CHARACTERIZATION OF LACTIC ACID BACTERIA ISOLATED FROM GOAT MILK CHEESE

CAROL, JUAN J.; SESÍN, ABRAHAM A.; LEDESMA, ANA E.; BUSTOS, ANA Y.

Congreso; LVII SAIB Meeting - XVI SAMIGE Meeting; 2021

Lactic acid bacteria (LAB) have been used for centuries because of their technological properties and their ability to improve the sensorial characteristics of foods. One of the main properties of these bacteria is the production of substances such as organic acids, which inhibit the growth of food pathogens and spoilage microorganisms. Another important property is the ability to hydrolyze proteins during fermentation processes, which can contribute to modifying the allergenic potential of milk proteins and the production of bioactive peptides. Therefore, the objective of the present work was to isolate and technologically characterize LAB from Santiago del Estero artisanal goat milk cheese. Samples of three different cheeses were taken and seeded in MRS medium, obtaining a count of LAB of 6,87 ± 0,19 log units in average. Fifty strains were presumptively identified as LAB strains since were Gram-positive (cocci or bacilli) and negative for catalase production. For this, 64% were cocci and the remaining 36% were bacilli. Among them, fourteen strains, identified by MALDI-TOF as Enterococcus faecium, Lactobacillus plantarum, Leuconostoc mesenteroides, Lactobacillus parabuchneri, among others, were tested for their growth and acidifying capacity in milk as well as their peptide, proteolytic, lipase and antimicrobial activity. All the strains evaluated showed the ability to grow in milk, in a range of 0.9 and 1.8 log CFU/mL, reaching a maximum of 9.09 log CFU/mL after 24 hours of incubation. In relation to the acidifying capacity, the pH decrease was between 0.57 and 1.34, and the lowest pH reached after 24 h of incubation was 5.02. The lactic acid production was between 19.3 and 45 μmoles/100 g of sample. In addition, the strains evaluated showed a variable increase in amino acid concentration after 24 h of grow in milk, with values ranging from 0.05 to 6.08 mg/mL. However, peptidase and lipase activity was practically non-existent in these strains. Finally, three strains were able to inhibit a pathogenic strain of Escherichia coli. These results indicate that lactic acid bacteria isolated from regional cheeses present interesting technological properties to be used in the design of fermented foods.