Presence of Yersinia enterocolitica in minced meat exposed to heat treatment in microwave oven

In this study, the thermal effect of microwave oven in different heats to that infected with Yersinia enterocolitica (O:3 P 41797) in minced meat was examined. Under sterile conditions, 500 g unheated minced meat samples were inoculated with 10(9) cells/ml of Y. enterocolitica pure culture. The infected samples were heat treated for 4 min at 150, 400, 550, 700 and 800 W and the core temperature of the samples were 35 degreesC, 54 degreesC, 67 degreesC, 80 degreesC, 97 degreesC, respectively in the microwave oven. The presence of Yersinia enterocolitica in the minced meat samples was determined on the days of 1, 7, 14, and 21 with Yersinia Selective Agar Base (Cefsulodin-Irgasan-Novobiocin, CIN Agar). At the end of exposing heat treatment in microwave oven at 35 degreesC for 4 min, following results were recorded, first day 2.17 log CFU/g, seventh day 5.82 log CFU/g, fourteenth day 7.89 log CFU/g, twenty first days 10.32 log CFU/g. The same experiment was conducted at 54 degreesC and the results were as follows; first day 2.17 log CFU/g, seventh day 5.71 log CFU/g, fourteenth day 7.79 log CFU/g, twenty first day 8.88 log CFU/g. On the other hand, minced meat exposed to heat treatment in microwave at 67 degreesC, 80 degreesC, 97 degreesC, no microorganism was found on the infected minced meat samples.