2. Universidad Cardenal Herrera-CEU

The individual and combined antilisterial efficiency of nisin, lactic acid and modified atmosphere packaging (MAP) was investigated. Raw ground pork was inoculated with a strain of Listeria monocytogenes and samples were distributed into twelve lots. Half of the lots were stored aerobically and the other six lots were packaged using the MAP. A different combination of nisin (N) and/or lactic acid (LA) was added to each lot (300 ppm N, 500 ppm N; 2% LA; 300 ppm N and 2% LA; 500 ppm N and 2% LA). All samples were stored at 4 °C for 21 days (samples with MAP) or 7 days (samples stored aerobically). The inactivation of L. monocytogenes in samples stored aerobically was attained mainly with the combination of 500 ppm N + LA; however, in samples with MAP, the L. monocytogenes population decreased 3.45 log with the addition of LA, and the combination N + LA increased the inactivation other 0.5 log.