Antilisterial Properties of Marinades during Refrigerated Storage and Microwave Oven Reheating against Post-Cooking Inoculated Chicken Breast Meat


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This study evaluated growth of Listeria monocytogenes inoculated on cooked chicken meat with different marinades and survival of the pathogen as affected by microwave oven reheating. During aerobic storage at 7 °C, on days 0, 1, 2, 4, and 7, samples were reheated by microwave oven (1100 W) for 45 or 90 s and analyzed microbiologically. L. monocytogenes counts on nonmarinated (control) samples increased (P < 0.05) from 2.7 ± 0.1 (day-0) to 6.9 ± 0.1 (day-7) log CFU/g during storage. Initial (day-0) pathogen counts of marinated samples were <0.5 log CFU/g lower than those of the control, irrespective of marinating treatment. At 7 d of storage, pathogen levels on samples marinated with tomato juice were not different (P ≥ 0.05; 6.9 ± 0.1 log CFU/g) from those of the control, whereas for samples treated with the remaining marinades, pathogen counts were 0.7 (soy sauce) to 2.0 (lemon juice) log CFU/g lower (P < 0.05) than those of the control. Microwave oven reheating reduced L. monocytogenes counts by 1.9 to 4.1 (45 s) and >2.4 to 5.0 (90 s) log CFU/g. With similar trends across different marinates, the high levels of L. monocytogenes survivors found after microwave reheating, especially after storage for more than 2 d, indicate that length of storage and reheating time need to be considered for safe consumption of leftover cooked chicken.