Inactivation of a non-pathogenic strain of E. coli by ionising radiation

Ionising radiation is an effective method to reduce pathogenic E. coli O157:H7 in meat and poultry products. Radiation sensitivity of bacteria, however, depends on several factors. After applying an irradiation dose of 1 kGy to cultures of the non-pathogenic strain of E. coli, DSM 498, grown and irradiated in nutrient broth, reductions of 3-4 decimal units were achieved (D10 = 0.27 kGy). If grown on minced turkey meat, however, reduction rates were lower (D10 = 0.47 kGy). Even lower reduction rates were obtained during irradiation of frozen meat (D10 = 0.72 kGy) compared to treatments at cooling temperatures (D10 = 0.48 kGy). For data evaluation, both, first order reduction kinetics and the Weibull model were compared. The results emphasise the necessity to determine inactivation kinetics in food matrices of target extrinsic factors (e.g. temperature).