Death kinetics of E-coli O157:H7, E.coli and natural contaminant coliforms in minced beef during irradiation treatment and storage

The death kinetics of Escherichia coli O157:H7, E. coli type 1 and total coliforms after irradiation treatment in minced beef were evaluated to analyze the effect of increasing irradiation doses. Irradiation doses ranging from 0.0 kGy to 1.5 kGy were evaluated for reducing numbers of E. coli during frozen storage conditions at -18degreesC for 30 days. D(10)values of E. coli O157:H7, E. coli type 1, and total coliforms were 0.245 kGy, 0.552 kGy and 0.293 kGy, respectively. An irradiation dose of 1.5 kGy was shown to inactivate 10(5) MPN/g of serotype O157:H7 and 10(3) MPN/g of E. coli type 1. This inactivation level might be considered safe for the consumption of minced beef. Finally, E. coli type 1 was found to be a suitable indicator for assessing the impact of irradiation on E. coli O157:H7 serotype. There was no significant change in numbers of bacteria during frozen storage.