Descrição
Artisanal cheese is one of the foods produced in the state of Minas Gerais, and being one of the artisanal products makes it one of the oldest and traditionally produced cheese in Brazil. This cheese is made with unpasteurized milk, which is an ideal substrate for the growth of different foodborne pathogens. In this sense, the aim of this study was to evaluate the growth and survival of L. monocytogenes in cheese at four different time points. Before the cheese was made, the milk was pasteurized and inoculated with L. monocytogenes. The growth of L. monocytogenes was evaluated at two locations in the cheese: in the center and on the rind. All cheeses were produced with a weight of 500 g, and the center was standardized to an average of 158.486 g ± 0.212, while the rinds showed an average variability of 195.952 ± 93.727 during the ripening period. Plate growth was assessed on Oxford agar supplemented with Listeria. Both the center and the rind, as well as the comparison between them, showed no significant statistical differences in growth during the ripening period. However, L. monocytogenes exhibited higher growth in the rinds than in the centers of the cheeses. Five typical colonies of L. monocytogenes identified on the plates at each stage of ripening were transferred to tryptic soy agar with 0.2% yeast extract and subsequently identified by MALDI-TOF in triplicate. The degree of identification had an average of 2.019 ± 0.109, confirming that the strains analyzed were L. monocytogenes. The results of Listeria confirmation by MALDI-TOF were represented graphically in a dendrogram using R, with E. coli as a reference for branch separation. These results confirmed that L. monocytogenes can survive in ripening cheese, growing differently in the center and on the rind, which is an important consideration in artisanal cheese production.
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