Multi-hurdle approach to controlling Listeria monocytogenes in further processed meat products

Processed meat products such as frankfurters, smoked sausage, and deli meat have gained popularity because consumers have less time for food preparation and demand more convenient meat items. Because these products are handled post processing and are often not reheated before consumption, the presence of Listeria monocytogenes (LM) is a concern. In this study, a multi-hurdle approach utilizing organic acids alone or in combination in the raw product and as a post-cook dip were evaluated on their ability to suppress the growth of LM. The turkey and ham deli loaves and beef frankfurters were processed, cooked, cooled, inoculated with Streptomycin-resistant LM, and then dipped. Treatments for the turkey deli loaves included potassium lactate (PL) in the raw product and sodium lactate (SL) and sodium diacetate (SD) dip, PL with SL/PL/SD dip, SL with SL/SD dip, and SL with SL/PL/SD dip while the ham deli loaves were treated with PL in the raw product and PL in the dip, PL with SL/PL/SD dip, SL/SD along with PL dip, and SL/SD with SL/PL/SD dip. The frankfurters contained PL in the raw product and SL in the dip, PL with SL/SD dip, SL/SD with SL dip, and SL/SD in the raw product and in the dip. For each product there was a positive (inoculated) and negative (non-inoculated) control, which was dipped in distilled water. Day 0, 7, 14, 21, 28, 42, and 56 were sampled for LM. There were no differences (P > 0.05) among the organic acid treatments in the turkey deli loaves at any time points, and all organic acid treatments increased the lag phase of LM compared to the positive control. In the ham deli loaves the treatments containing PL in the raw product and SL/PL/SD in the dip, SL/SD with PL dip, and SL/SD with SL/PL/SD dip had similar inhibition effects on LM. The SL/SD with SL dip and SL/SD with SL/SD dip effectively inhibited the growth of LM in the frankfurters. By utilizing this intervention, multi-hurdle approach using organic acids, the industry can minimize LM growth in ready-to-eat (RTE) products, decreasing the occurrences of outbreaks.