The evaluation of gamma irradiation and cold storage for the reduction of Campylobacter jejuni in chicken livers

Recent outbreaks of Campylobacter mediated disease attributed to undercooked chicken livers have highlighted a continuing need for methods to reduce Campylobacter numbers in these types of food products. In this study, gamma irradiation is evaluated for its effectiveness in reducing Campylobacter jejuni numbers in experimentally contaminated chicken livers. A wide range of radiation doses were evaluated in conjunction with cold storage parameters, before and after irradiation. Storage of chicken livers at −20 °C prior to radiation treatment, as expected, increased C. jejuni radiation resistance. Livers previously stored at −20 °C exhibited D10 values of 0.748 kiloGray (kGy) compared to livers without previous storage that had a significantly lower D10 value of 0.361 kGy. Cold storage conditions post-irradiation at both 4 °C and −20 °C further reduced the C. jejuni numbers over those reduced by the initial irradiation. The largest reduction (3.8 logs) of C. jejuni numbers in livers produced by combining irradiation and cold storage was achieved using 0.8 kGy of radiation followed by 1 week storage at −20 °C. This reduction of 3.8 logs was not determined to be significantly different from the 3.5 log reduction achieved with the same radiation dose (0.8 kGy) after only 48 h of subsequent storage at −20 °C. •Radiation doses of 1.8 kGy produce >5 log reduction in C. jejuni numbers in livers.•Cold storage post-irradiation produces additional C. jejuni reductions of >1 log.•Cold storage of livers before irradiation more than doubled the D10 value.