Viability of Shiga Toxin-Producing Escherichia coli, Salmonella spp., and Listeria monocytogenes During Preparation and Storage of Fuet, a Traditional Dry-Cured Spanish Pork Sausage

Authors: Porto-Fett, Anna; ESPUNA, ESTEVE - Espuna Llc; Shane, Laura; Shoyer, Brad; MCGEARY, LIANNA - Former ARS Employee; STAHLER, LAURA - Former ARS Employee; Osorio, Manuela; Luchansky, John

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2022
Publication Date: 3/22/2022
Citation: Porto Fett, A.C., Espuna, E., Shane, L.E., Shoyer, B.A., Mcgeary, L., Stahler, L., Osoria, M., Luchansky, J.B. 2022. Viability of Shiga toxin-producing Escherichia coli, Salmonella spp., and Listeria monocytogenes during preparation and storage of Fuet, a traditional dry-cured Spanish pork sausage. Journal of Food Protection. https://doi.org/10.4315/JFP-21-356.
DOI: https://doi.org/10.4315/JFP-21-356

Interpretive Summary: One of the most popular Spanish sausage is fuet, a small diameter (ca. 35 mm), low-acid (pH 5.3 to pH 6.2), dry-cured pork sausage with marked sensory attributes, having a very sweet, yet mild taste, with strong black pepper notes, which emanates from the Catalonia region of Northeast Spain. On occasion, however, foodborne pathogens such as Shiga toxin-producing Escherichia coli (STEC), Salmonella spp. (Sal), and Listeria monocytogenes (Lm) have been linked to product recalls and human illnesses attributed to fuet. Thus, the objective of this study was to evaluate a traditional recipe and make protocol for fuet, in combination with levels of available water (aw), high pressure processing (HPP), and extended storage, to control these three pathogens in the final product. Our results established that fermentation of fuet (23 +/- 2C and 95 +/- 4% relative humidity to an end-point pH of lower than or equal to pH 5.3) was only capable of eliminating ca. 2 cells per gram for each of the three pathogens tested. Further reductions of ca. 100, 30, and 6 cells per gram in levels of STEC, Salmonella spp., and L. monocytogenes, respectively, were achieved after drying fuet to aw 0.89, whereas additional reductions of ca. 1,600, 50, and 100 cells per gram, respectively, were achieved when fuet was dried to aw 0.86. In summary, for fuet that was fermented and dried to aw 0.89, and irrespective of whether chubs were or were not pressure treated, total reductions of ca. 2,500 to 2,000,000 cells per gram were achieved for STEC, Salmonella spp., and L. monocytogenes after storage for 30 days at 20C. For fuet that was fermented and dried to aw 0.86, and irrespective of whether chubs were or were not pressure treated, total reductions of 160,000 to 5,000,000 cells per gram were achieved for all three pathogens after storage for 30 days at 20C. These data also established that fuet, as manufactured by the process detailed/validated herein, is both safe for consumers and suitable for the marketplace.

Technical Abstract: Viability of Shiga toxin-producing Escherichia coli (STEC), Salmonella spp., and Listeria monocytogenes was monitored during preparation and storage of fuet, a traditional Spanish sausage. Coarse ground pork (ca. 35% fat) was mixed with salt (2.5%), dextrose (0.3%), starter culture (ca. 7.0 log CFU/g), celery powder (0.5%), and ground black pepper (0.3%), and then separately inoculated with a multi-strain cocktail (ca. 7.0 log CFU/g) of each pathogen. The batter was stuffed into a ca. 42 mm natural swine casing and fermented at 23 +/- 2°C and ca. 95 +/- 4% relative humidity (RH) to lower than or equal to pH 5.3 (less than 48 h). Sausage were then dried at 12 +/- 2C and ca. 80 +/- 4% RH to a final water activity (aw) of aw 0.89 (up to 33 days) or aw 0.86 (up to 60 days). Next, a portion of each batch of fuet was subjected to high pressure processing (HPP; 600 MPa for 3 min) before chubs were vacuum-packaged and stored for up to 30 days at 20 +/- 2C. Overall, pathogen numbers remained relatively unchanged after fermentation (i.e., lower than or equal to 0.3 log CFU/g reduction), whereas reductions of ca. 1.2 to 3.2 log CFU/g were achieved after drying fuet to aw 0.89 or aw 0.86. Regardless if fuet was or was not pressure treated, additional reductions of ca. 2.0 to lower than or equal to 4.9 log CFU/g were achieved after 30 days of storage at 20C. For non-HPP treated fuet dried to aw 0.89 and stored for 30 days at 20C, total reductions of lower than or equal to 5.1 log CFU/g in levels of STEC or Salmonella spp. were achieved, whereas levels of L. monocytogenes were reduced by only ca. 3.4 log CFU/g. Total reductions of lower than or equal to 5.2 log CFU/g in levels of all three pathogens were achieved after drying non-HPP treated fuet to aw 0.86. For fuet dried to aw 0.89 or aw 0.86, pressure treated, and then stored for 30 days at 20C, total reductions of lower than or equal to 6.1 log CFU/g in levels of all three pathogens were achieved. The processing parameters tested herein, with or without application of HPP, validated the requisite reductions of lower than or equal to 2.0- or lower than or equal to 5.0-log CFU/g in levels of STEC, Salmonella spp., and/or L. monocytogenes during preparation and storage of fuet.