a b s t r a c tThis study reports the effect of different concentrations of nisin (0, 100 and 500 IU mL À1 ) against Staphylococcus aureus in Minas Traditional Serro cheese manufactured with raw milk. We also evaluated the influence of nisin on the physicochemical properties, mechanical characteristics and colour of the cheese over 60 days of ripening. Nisin was effective in reducing S. aureus count in Serro cheese; a reduction of 1.2 and 2.0 log cycles in S. aureus count was observed from the 7th day of ripening for cheese containing 100 IU mL À1 and 500 IU mL À1 of nisin, respectively, compared with the control sample. The major changes in physicochemical properties, mechanical characteristics and colour were associated with cheese ripening, except for the index of ripening, which was lower in the presence of nisin. The addition of nisin is a powerful tool to contribute to the safety of traditional cheese produced with raw milk.

a b s t r a c tCheese produced with raw milk can be a risk to consumer health. It is known that lactic acid bacteria present in raw milk and in natural starters can produce antimicrobial compounds against some foodborne bacteria. This work aimed to evaluate the survival of Listeria innocua in Minas Traditional Serro cheese during cheese ripening. The cheeses were inoculated with 10 1 , 10 2 or 10 3 CFU mL À1 of the bacterium and were analyzed for 60 days of ripening at 30°C. It was observed that the time and the dose of bacteria inoculated affected (p < 0.05) the survival of L. innocua. Even when the lowest dose was inoculated, at the end of the 60 days, approximately 10 2 CFU mL À1 of L. innocua was detected in the cheese. The lactic acid bacteria present in the milk and in the natural starter were not sufficient to guarantee the absence of L. innocua in Minas Traditional Serro cheese even after 60 days of storage, as is required by Brazilian legislation.

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