The effect of short-time microwave exposures on Listeria monocytogenes inoculated onto chicken meat portions

Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of chicken meat samples which were inoculated with L. monocytogenes. Drumettes of broiler carcasses were soaked in fully growth of L. monocytogenes in Brain-Heart Infusion broth. The swab samples were taken from the inoculated samples, after various times of radiation (۱۰, ۲۰, ۳۰, ۴۰, ۵۰, ۶۰, ۷۰ and ۸۰ sec), using a domestic MW oven at full power. Following exposures, viable counts and surface temperaturemeasurements were performed. The bacterial counts were performed on Oxford agar. The results indicated that equal or longer than ۶۰ sec exposures of chicken portions to MW heating which enhances the median surface temperature more than ۷۴ ˚C could eliminate the superficial contamination of chicken meat with L. monocytogenes. Statistical analysis showed samples with equal or longer than ۶۰ sec exposures to MW heating had significant decrease in population of inoculated bacteria compared with positive control group(p < ۰.۰۵). Pearson correlation showed a significant correlation between the bacterial population and temperature of samples due to MW exposure (p < ۰.۰۰۱, r = – ۰.۸۷۹ and r۲ = ۰.۷۷۳).

Keywords:

chicken meat , Listeria monocytogenes , Microwave