DSC Sodium Lactate, Sodium Diacetate and Pediocin on the Heat Inactivation of Listeria monocytogenes on the Surface of Frankfurters

The effects and interactions of heating temperature (55 to 60 ̊C), sodium lactate (NaL; 0.0 to 4.8%), sodium diacetate (SDA; 0.0 to 0.4, w/w) and pediocin (0 to 10,000AU) on the heat resistance of L. monocytogenes 101M on the surface of frankfurters were examined. Thermal death times were determined by dipping vacuum packaged frankfurters in a circulatory water bath set to required temperatures. The samples were plated on selective modified oxford formulation and nonselective brain heart infusion agar to determine injury and total survivors. Decimal reduction times (D-value) were calculated. The D-values were analyzed by first order response surface regression for temperature, NaL, SDA and pediocin. The observed D-value ranged from 1.6 to 32 min for franks having different combination of NaL, SDA and pediocin treated at different temperatures according to central composite design. Temperature had the most prominent impact on decreasing the D-value of L. monocytogenes. However, a combination of temperature with pediocin, NaL and SDA was more effective at decreasing the Dvalue of L. monocytogenes as compared to control. A mathematical model describing the combined effects of temperature, Nal, SDA and pediocin on the thermal inactivation of L. monocytogenes was developed. The model can predict D-values for any combination of temperatures, Nal, SDA and pediocin that are within the range of those tested. This model will benefit the industry and consumers by providing possibilities of milder thermal treatment of antimicrobial incorporated readyto-eat meat products while insuring their safety.