THE EFFECT OF MICROWAVE AND CONVENTIONAL COOKING ON THE TEMPERATURE PROFILES AND MICROBIAL-FLORA OF MINCED BEEF

Beef mince samples were cooked to the rare, medium and well done states by microwave and conventional oven methods. The raw samples all contained large numbers of contaminating organisms and low numbers of Listeria monocytogenes were detected in the majority of samples. A substantial proportion of the contaminating flora survived in mince cooked by microwaves to the rare, medium and well done states, prior to a 30-min standing period. Listeria monocytogenes survived in all samples cooked by microwaves to the rare state, prior to the standing period and was still present in one of three after the standing period. It was also detected in one of three samples cooked to medium prior to a standing period. This organism was not detected in mince cooked by conventional oven methods. In all the samples cooked by microwaves with a standing period and samples cooked to rare and medium by conventional oven, survival of some of the microflora occurred. The survival rate decreased with the severity of the cooking treatment.