Inhibition of Listeria monocytogenes by Carnobacterium piscicola in Fresh and Pasteurized Crab Meat
The ability of Carnobacterium piscicola to inhibit Listeria monocytogenes at different concentration levels, storage times and temperatures was examined. Twenty-five g samples of fresh and previously pasteurized blue crab meat were placed into separate sterile 59 ml soufflé cups, inoculated with 0.1 ml C. piscicola at three different concentration levels (2, 4 and 6 log CFU/g) and 0.1 ml (log 2.0 CFU) of L. monocytogenes (ratios of 1:1, 2:1 and 3:1 of C. piscicola to L. monocytogenes). Fresh crab meat and previously pasteurized crab meat was stored at 4°C or 10°C and sampled until aerobic plate count reached ≥ 7 log CFU/g, which was considered spoilage. At each sampling time, crab meat inoculated with both organisms was plated on modified Lactobacillius deMan Rogosa Sharpe (pH 7) and modified oxford agar (MOX). Uninoculated crab meat was plated on trypticase soy agar and meat inoculated with only L. monocytogenes was plated on MOX. In both fresh and pasteurized crab meat, regardless of the inoculation levels, L. monocytogenes and C. piscicola followed similar growth trends. C. piscicola reduced growth of L. monocytogenes in pasteurized crab meat after 14 day at 4°C and 10 day at 10°C (P < 0.05).