Impact of Storage Temperature and Product pH on the Survival of Listeria monocytogenes in Vacuum-Packaged Souse

Abstract

Souse is a fully cooked, ready-to-eat gelled pork product. There is a zero-tolerance policy for Listeria monocytogenes in ready-to-eat meat products. The survival and/or growth of L. monocytogenes in souse is unknown. The effectiveness of three different souse formulations (pH 4.3, 4.7, and 5.1) for controlling the growth of L. monocytogenes at two refrigerated storage temperatures (5 and 10 degrees C) was evaluated. All products were vacuum packaged. Uninoculated product was prepared as the control, and other products were artificially surface contaminated with a three-strain cocktail of L. monocytogenes (10(6) CFU/ cm2). Microbial counts were obtained on selective and nonselective media twice weekly through 8 weeks of storage. Souse did not support the growth of L. monocytogenes regardless of product formulation or storage temperature. At 5 degrees C, D-values for products with pH values of 4.7 and 5.1 were not different, but survival of L. monocytogenes in product with a lower pH (4.3) was decreased compared with survival in products with higher pH values (P < 0.05). Survival of L. monocytogenes was not impacted by storage temperatures (P > 0.05). Consumer acceptability (n = 75 souse consumers) of pH 4.3 products was not different from that for (typical) pH 4.7 products (P > 0.05). These results indicate that conventionally produced souse does not support the growth of L. monocytogenes and that inactivation of the organism is more likely in products formulated at a lower pH (< or = 4.3) without affecting consumer acceptance.

Effect of Storage Temperatures and Cooking Times on Viability of Listeria monocytogenes and Escherichia coli O157:H7 Inoculated in/on Goetta

“…In contrast, Kim et al . () reported that souse, a specialty, gelled RTE meat made with pork trimmings and pork by‐products, did not support the growth of L. monocytogenes when the product was stored at 4 or 10C for up to 32 days. The authors attributed the inhibition of the pathogen on souse to the lower pH of the product (pH 4.3 to pH 5.1) and, in part, due to the addition of acetic acid to the formulation.…”