CULTURE MEDIA COMPARISON FOR THE ENUMERATION OF LISTERIA-MONOCYTOGENES IN REFRIGERATED VACUUM-PACKAGED TURKEY BOLOGNA MADE WITH CHEMICAL ADDITIVES

Sliced cooked turkey bologna of varying additive formulations was surf ace-inoculated with Listeria monocytogenes (2.18-2.58 log CFU/g), vacu um packaged and stored at 4 degrees C. Growth of the pathogen was enum erated with five different agar media. Overall, tryptic soy agar and m odified Oxford agar recovered higher numbers of colonies, followed by mannitol-phenol redesculin-ferric ammonium citrate agar and lithium ch loride-phenylethanol-moxalactam (LPM) agar, while LPM-potassium tellur ite agar recovered significantly fewer colonies. Sodium acetate (5 g/k g; pH 6.63), sodium lactate (20 g/kg; pH 6.73) and potassium sorbate ( 2.6 g/kg; pH 6.59) were highly inhibitory against L. monocytogenes dur ing the 28-day storage period. The effect of sodium bicarbonate (10 g/ kg, pH 7.59) however, was not significantly different than the control (pH 6.58). (C) 1995 Academic Press Limited