Effect of inhibitory liquid smoke fractions on Listeria monocytogenes during long-term storage of frankfurters

Listeria monocytogenes is a potential health hazard that sometimes finds harborage in facilities that manufacture ready-to-eat meats, including frankfurters. Our objectives were to examine the effect of select liquid smoke extracts on control of L. monocytogenes on frankfurters. Frankfurters were either obtained locally at retail (containing lactate-diacetate) or manufactured for us in-house or by a local processor (without added lactate-diacetate). In challenge studies of retail franks containing lactate-diacetate, low levels of L. monocytogenes were able to increase by 2 to 8 log on 5 of 10 brands tested when held at 1.6 degrees C (35 degrees F). Treatments with liquid smoke extracts were able to reduce and control growth of L. monocytogenes on the most permissive franks for 10 weeks when treated for as long as 90 s to as little as 5 s versus untreated controls. Effective control of L. monocytogenes was also obtained when dipped for as short as 1 s or when dropped through an atomized mist produced by a pressurized spray canister. Frankfurters manufactured without lactate-diacetate by a large commercial manufacturer of franks were sprayed with liquid smoke by using a commercial device as they exited the peeler. When inoculated at three different levels (10(1), 10(2), and 10(3) CFU) with a four-strain cocktail of L. monocytogenes and stored at 6 degrees C (43 degrees F), the smoke-treated samples again demonstrated effective control of L. monocytogenes relative to untreated control samples. Frankfurters produced in-house without lactate-diacetate and treated while still in the casing also showed suppression of Listeria compared with controls. The data show that surface application of liquid smoke extracts by dipping or spraying may inhibit the growth of L. monocytogenes on frankfurters during shelf life and should facilitate a claim as an alternative 2, and possibly alternative 1, process for (U.S. Food and Drug Administration) hazard analysis and critical control point purposes.