Thermal inactivation of Salmonella spp. in pork burger patties

Abstract

<p>Predictive models, to estimate the reduction in <i>Escherichia coli</i> O157:H7 concentration in beef burgers, have been developed to inform risk management decisions; no analogous model exists for <i>Salmonella</i> spp. in pork burgers. In this study, "Extra Lean" and "Regular" fat pork minces were inoculated with <i>Salmonella</i> spp. (<i>Salmonella </i>4,[5],12,i:-, <i>Salmonella</i> Senftenberg and <i>Salmonella</i> 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 <i>Salmonella</i> enumerated. A generalised linear logistic regression model was used to develop a predictive model for the <i>Salmonella</i> concentration based on the internal endpoint temperature. It was estimated that in pork mince with a fat content of 6.1%, <i>Salmonella</i> 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 <i>Salmonella</i> concentration estimated to occur when the geometric centre temperature reaches 63 °C. The fat content influenced the rate of <i>Salmonella</i> inactivation (<i>P</i> = 0.043), with <i>Salmonella</i> 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 (<i>P</i> = 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. <i>Salmonella</i> serovar did not significantly affect the model intercepts (<i>P</i> = 0.86) or slopes (<i>P</i> = 0.10) of the fitted logistic curve. This predictive model can be applied to estimate the reduction in <i>Salmonella</i> in pork burgers after cooking to a specific endpoint temperature and hence to assess food safety risk.</p>