Thermal inactivation and kinetic parameters for Campylobacter jejuni on chicken skin

Abstract

New Zealand has a higher reported incidence rate of campylobacteriosis than other developed countries. It has been suggested that this may be due to the emergence of heat-resistant strains that can survive normal cooking. To test this, typed Campylobacter strains ST474 and ST48 were inoculated onto slices of chicken skin <18 mm in diameter and 4 mm thick using a pipette, and placed in a special aluminium cell, which was heated to a predetermined temperature (in the range of 56.5 to 65 °C) using a temperature-controlled water bath. Survivor curves were plotted, and GlnaFit software was chosen to fit the experimental data; inactivation parameters were estimated using 1-step and 2-step regression. The D values and z values were in the range of 3–6 s and 8–11 °C, respectively. The D values at 60 and 56 °C were in the range of 12–41 s. These D values are in general agreement with previously published reports. Thus, New Zealand’s higher reported rate of campylobacteriosis is possibly due to factors other than the emergence of heat-resistant strains.