Inactivation of Listeria monocytogenes and Shiga Toxin-Producing Escherichia coli in “Soupie,” a Homemade Sopressata

Abstract

Viability of Listeria monocytogenes and Shiga toxin-producing Escherichia coli (STEC) was monitored in “soupie,” a homemade soppressata. Coarse-ground fresh ham was mixed with nonmeat ingredients, a starter culture (ca. 6.0 log CFU/g), and one pathogen cocktail (ca. 6.5 log CFU/g). The batter was then fine ground, stuffed into fibrous casings, and fermented at 26.7°C and ca. 90 ± 5% relative humidity (RH) for ≤ 48 h to achieve a pH of ≤ 5.3. Chubs were dried at 15.6°C and ca. 87 ± 5% RH for 5 days, flattened under weights for 3 days, and then dried for an additional 21 days at 4°C and ca. 73 ± 5% RH. Half of the chubs were vacuum sealed individually in bags with 8 mL of sunflower oil, and the other half were submerged in sunflower oil (ca. 1.5 L) within covered plastic containers; all chubs were stored for 6 months at 20°C. Fermentation and drying delivered a ≤ 1.2-log reduction in levels of both pathogens. Regardless of storage conditions, a ≥ 5.0-log reduction was observed within 1 and 4 months of storage at 20°C for STEC and L. monocytogenes, respectively. These data establish that artisanal soupie, prepared and stored as described here, does not provide a favorable environment for pathogen persistence or proliferation.