The effect of short-time microwave exposures on Escherichia coli O157:H7 inoculated onto beef slices

Abstract

Escherichia coli O157:H7 is an important human pathogen causing haemorrhagic colitis, hemolyticureamic<br><br>syndrom and thrombotic thrombocytopenic purpura. In this study the effect of microwave<br><br>irradiation of beef samples which were inoculated with E. coli O157:H7 were investigated. The portions<br><br>of fresh beef slices weighting 200 g each and about 10 × 10 × 2 cm in size, were soaked in fully growth<br><br>of E. coli O157:H7, in BHI broth. The swab samples were taken from the contaminated samples, after<br><br>different times of radiation (10, 20, 30, 40 and 50 s), using a domestic microwave oven at full power. The<br><br>bacterial counts were performed by using surface plating on sorbitol Mac Conkey agar supplemented<br><br>with cifixime and potassium tellurite. After each experiment the surface temperature of treated samples<br><br>were measured. The experiment was carried out in triplicate and it was concluded that the microwave<br><br>radiation which enhance the surface temperature more than 70°C, can eliminate the superficial<br><br>contamination of cattle beef slices with E. coli O157:H7