Thermal inactivation of Salmonella spp. in pork burger patties

Predictive models, to estimate the reduction in <em>Escherichia coli</em> O157:H7 concentration in beef burgers, have been developed to inform risk management decisions; no analogous model exists for <em>Salmonella</em> spp. in pork burgers. In this study, “Extra Lean” and “Regular” fat pork minces were inoculated with <em>Salmonella</em> spp. (<em>Salmonella</em> 4,[5],12,i:-, <em>Salmonella</em> Senftenberg and <em>Salmonella</em> Typhimurium) and formed into pork burger patties. Patties were cooked on an electric skillet (to imitate home cooking) to one of seven internal temperatures (46, 49, 52, 55, 58, 61, 64 °C) and <em>Salmonella</em> enumerated. A generalised linear logistic regression model was used to develop a predictive model for the <em>Salmonella</em> concentration based on the internal endpoint temperature. It was estimated that in pork mince with a fat content of 6.1%, <em>Salmonella</em> survival will be decreased by − 0.2407 log₁₀ CFU/g for a 1 °C increase in internal endpoint temperature, with a 5-log₁₀ reduction in <em>Salmonella</em> concentration estimated to occur when the geometric centre temperature reaches 63 °C. The fat content influenced the rate of <em>Salmonella</em> inactivation (<em>P</em> = 0.043), with <em>Salmonella</em> survival increasing as fat content increased, though this effect became negligible as the temperature approached 62 °C. Fat content increased the time required for patties to achieve a specified internal temperature (<em>P</em> = 0.0106 and 0.0309 for linear and quadratic terms respectively), indicating that reduced fat pork mince may reduce the risk of salmonellosis from consumption of pork burgers. <em>Salmonella</em> serovar did not significantly affect the model intercepts (<em>P</em> = 0.86) or slopes (<em>P</em> = 0.10) of the fitted logistic curve. This predictive model can be applied to estimate the reduction in <em>Salmonella</em> in pork burgers after cooking to a specific endpoint temperature and hence to assess food safety risk.