Inactivation of Listeria innocua on frankfurters that contain potassium lactate and sodium diacetate by flash pasteurization

Listeria monocytogenes, a psychrotrophic foodborne pathogen, is a recurring postprocess contaminant on ready-to-eat meat (RTE) products, including frankfurters. Potassium lactate (PL) and sodium diacetate (SDA) are FDA-approved antimicrobials that inhibit the growth of L. monocytogenes when incorporated into the formulation of fine emulsion sausage. Flash (steam) pasteurization (FP) has been shown to reduce levels of L. monocytogenes, and its surrogate L. innocua, on frankfurter surfaces. The ability of FP to inactivate and prevent the growth of the L. monocytogenes surrogate L. innocua in a pilot plant setting was investigated. FP treatment (1.5 s, 121 degrees C) of single layers of frankfurters that were surface-inoculated with either 5,4, or 3 log CFU/g of L. innocua immediately before FP (1.5 s, 121 degrees C) resulted in log reductions of 1.97 (+/- 0.11), 2.03 (+/- 0.10), or 2.07 (+/- 0.14), respectively. Inoculum level had no effect on the inactivation of L. innocua. Following 8 wk of refrigereated storage (4 degrees C), L. innocua levels decreased by 0.5 log in non-FP-treated frankfurter packs, while the 2 log reduction of L. innocua was maintained for FP-treated frankfurters. FP (1.5 s, 121 degrees C) had no effect on frankfurter color or texture. Because the numbers of L. monocytogenes associated with contaminations of ready-to-eat meats are typically very low, the use of FP in combination with PL and SDA has the potential to reduce the number of frankfurter recalls and foodborne illness outbreaks.