Effects of salts of organic acids on the survival of Listeria monocytogenes in soft cheeses

The purpose of this study was to determine the effect of sodium lactate and sodium propionate, both in combination with sodium acetate, on strains of Listeria monocytogenes in artificially inoculated soft cheeses. Minas Frescal and Coalho cheeses, inoculated with a mix of L. monocytogenes 1/2a and Scott A, underwent two treatments: 2% (w/v) sodium lactate in combination with 0.25% (w/v) sodium acetate and 2% (w/v) sodium propionate in combination with 0.25% (w/v) sodium acetate. The samples were analysed immediately and after 7 days at 10 °C. The growth of the pathogen was inhibited in cheeses containing the salts of organic acids, and the effects of treatment were statistically significant (P < 0.05). However, there was no difference between the types of treatment applied. Our data demonstrate that the effectiveness of the salts of organic acids depended on the initial concentration of L. monocytogenes and that a higher concentration of the salts is necessary to ensure sustained inactivation of target pathogens because they are weakly antilisterial when the soft cheeses are stored at 10 °C.