EVALUATION OF LACTIC-ACID BACTERIUM FERMENTATION PRODUCTS AND FOOD-GRADE CHEMICALS TO CONTROL LISTERIA-MONOCYTOGENES IN BLUE-CRAB (CALLINECTES-SAPIDUS) MEAT

Fresh blue crab (Callinectes sapidus) meat was obtained from retail ma rkets in Florida and sampled for viable Listeria monocytogenes. The pa thogen was found in crabmeat in three of four different lots tested by enrichment and at levels of 75 CFU/g in one of the same four lots by direct plating. Next, crabmeat was steam sterilized, inoculated with a three-strain mixture of L. monocytogenes (ca. 5.5 log(10) CFU/g), was hed with various lactic acid bacterium fermentation products (2,000 to 20,000 arbitrary units [AU]/ml of wash) or food-grade chemicals (0.25 to 4 M), and stored at 4 degrees C. Counts of the pathogen remained r elatively constant in control samples during storage for 6 days, where as in crabmeat washed with Perlac 1911 or MicroGard (10,000 to 20,000 AU), numbers initially decreased (0.5 to 1.0 log(10) unit/g) but recov ered to original levels within 6 days. Numbers of L. monocytogenes cel ls decreased 1.5 to 2.7 log(10) units/g of crabmeat within 0.04 day wh en washed with 10,000 to 20,000 AU of Alta 2341, enterocin 1083, or Ni sin per ml. Thereafter, counts increased 0.5 to 1.6 log(10) units with in 6 days. After washing with food-grade chemicals, modest reductions (0.4 to 0.8 log(10) unit/g) were observed with sodium acetate (4 M), s odium diacetate (0.5 or 1 M), sodium lactate (1 M), or sodium nitrite (1.5 M). However, Listeria counts in crabmeat washed with 2 M sodium d iacetate decreased 2.6 log(10) units/g within 6 days. In addition, tri sodium phosphate reduced L. monocytogenes counts from 1.7 (0.25 M) to >4.6 (1 M) log(10) units/g within 6 days. These results demonstrate th at numbers of L. monocytogenes on crabmeat may be reduced appreciably by ''washing'' with select antimicrobial agents.