The effects of nisin on Staphylococcus aureus count and the physicochemical properties of Traditional Minas Serro cheese

This study reports the effect of different concentrations of nisin (0, 100 and 500 IU mL(-1)) 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(-1) and 500 IU mL(-1) 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. (C) 2010 Elsevier Ltd. All rights reserved.