INFLUENCE OF LACTIC-ACID AND MODIFIED ATMOSPHERE ON THERMAL-DESTRUCTION OF LISTERIA-MONOCYTOGENES IN CRAWFISH TAIL MEAT HOMOGENATE

Precooked homogenized crawfish tail meat was inoculated with listeria monocytogenes, treated with lactic acid, and packaged in various atmospheres for D value determinations at 60C. D-60 values using 0.0, 0.5, 0.75, and 1.0% lactic acid (LA) treated meat were 4.68, 4.41, 3.46, and 2.49 min, respectively. LA increased sensitivity of L. monocytogenes to heat but this was not solely due to a reduction of pH. Sensory analyses of odor, color, taste, and texture of uninoculated whole crawfish tail meat demonstrated no significant differences (P > 0.05) between LA treated samples and controls. D-60 values for the bacterium in crawfish tail meat homogenate packed in air, O-2, CO2, or N-2 were 10.58, 9.22, 11.68, or 12.97 min, respectively, which were not significantly different (P > 0.05). When 1% LA was added, significant decreases (P < 0.05) in D-60 values were observed in each packaging atmosphere. Similar (P > 0.05) D-60 values for crawfish tail meat treated with 1% LA and packed in air, O-2, CO2, or N-2 were 3.44, 3.88, 3.48, or 3.08, respectively. These results show that heat treatments of 60C were lethal to L. monocytogenes in packaged crawfish tail meat homogenate regardless of package atmosphere. Additionally, LA increased the lethality of heat to the bacterium in all tested package atmospheres.