Lethality and post-package pasteurization treatments for reducing Salmonella spp., Shiga toxin-producing Escherichia coli and Listeria monocytogenes in reduced-moisture ready-to-eat meat and poultry products

The first objective of this study was validating the effectiveness of a commercial cooking smokehouse cycle as a lethality treatment for efficacy reduction of Salmonella and Escherichia coli (E. coli) surface-inoculated with a multistrain mixture of each pathogen separately onto whole muscle beef and poultry strips. As a second objective determine the appropriate time and temperature for post package pasteurization in three different time periods (3-, 6-, and 10 min) at two different temperatures (77 °C and 82 °C) on reducing Listeria monocytogenes (L. monocytogenes) on beef and chicken reduced moisture whole muscle strips. Fully cooked beef and chicken strips (n = 24 per replication) were cut and weighed into 10-g portions. A four-strain cocktail was prepared of L. monocytogenes for inoculation. Five replications of the study were performed. Samples were inoculated with 200 µl of the mixed multistrain cocktail, and cell attachment allowed for 20 min then repeated on the opposite side. The positive control samples (0 min) samples (n = 15 total) per each temperature were placed individually into filter bags. Inoculated meat strips were vacuum packaged and placed into a circulating water bath at their designated time (3-, 6-, or 10 min) and temperature (77 °C or 82 °C). Samples were aseptically transferred to filtered bags, and 90 ml of buffered peptone water (BPW) was added. Samples were stomached, and serial dilutions were made using 9 ml BPW blanks. Samples were plated to a thin layer tryptic soy agar (TSA) overlaid oxford modified agar base (MOX) supplemented with Moxalactam for L. monocytogenes and incubated at 37 °C for 24 h. Counts were averaged and converted to log CFU/g prior statistical analysis. Samples producing an inconclusive manual plate count estimate (below detection limit) were analyzed via Dupont® BAX® PCR analysis. Smokehouse cycle treatment on both chicken and beef reduced moisture whole muscle strips Salmonella and E. coli reduction was ≥ 7.5 log CFU/g. The recommended time and temperature for post-package pasteurization for inactivation of L. monocytogenes is 77 C for 6 min showed a reduction of ≥ 6.18 log CFU/g for both chicken and beef reduced moisture whole muscle strips. As well as treatments with more extended time and higher temperature were effective on the L. monocytogenes inactivation. Effectiveness of the smokehouse cooking cycle was validated with the reduction of Salmonella and E. coli required by the Food Safety and Inspection Service (FSIS) in the United States Department of Agriculture (USDA). Post-packaging pasteurization at different time periods showed L. monocytogenes reduction to the point that was below the limit of detection.