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.

ABSTRACT: The primary objective of this study was to monitor viability of Shiga toxin-producing Escherichia coli (STEC), Salmonella spp., and Listeria monocytogenes during preparation and storage of fuet. Regarding methodology, 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 multistrain 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 to ≤pH 5.3 (≤48 h). Sausages were then dried at 12 ± 2°C and ca. 80% ± 4% relative humidity to a water activity (aw) of 0.89 (within 33 days) or aw 0.86 (within 60 days). 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 30 days at 20 ± 2°C. The results revealed that pathogen numbers remained relatively unchanged after fermentation (≤0.35 log CFU/g reduction), whereas reductions of ca. 0.8 to 3.2 log CFU/g were achieved after drying fuet to aw 0.89 or 0.86. Regardless of whether fuet was or was not pressure treated, additional reductions of ca. 2.2 to ≥5.3 log CFU/g after drying were achieved following 30 days of storage at 20°C. For non-HPP-treated fuet dried to aw 0.89 and stored for 30 days at 20°C, total reductions of ≥5.3 log CFU/g in levels of STEC or Salmonella spp. were achieved, whereas levels of L. monocytogenes were reduced by ca. 3.6 log CFU/g. Total reductions of ≥5.3 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 0.86, that were pressure treated and then stored for 30 days at 20°C, total reductions of >6.2 log CFU/g in levels of all three pathogens were achieved. In conclusion, the processing parameters tested herein, with or without application of HPP, validated that reductions of ≥2.0 or ≥5.0 log CFU/g in levels of STEC, Salmonella spp., and L. monocytogenes were achieved during preparation and storage of fuet.

Meat Bars: A Survey To Assess Consumer Familiarity and Preparation Parameters and a Challenge Study To Quantify Viability of Shiga Toxin-Producing Escherichia coli Cells during Processing and Storage.

Meat bars are dried snacks containing a mixture of meat, berries, and nuts. To explore consumer awareness of meat bars, we conducted two online, nationally representative surveys and established that 70.8% (743 of 1,050) of U.S. citizens were unfamiliar with this product. When asked to check all answers that applied, most of the 545 respondents (who were recruited based on their familiarity with meat bars) preferred beef (n = 385) as the protein source, followed by chicken (n = 293), pork (n = 183), and turkey (n = 179). Most meat bars were purchased from grocery stores (n = 447), followed by online orders (n = 130) and outdoor stores (n = 120). When asked specifically whether they made their own meat bars, 17.8% of respondents (97 of 545) replied "yes," the majority (52 of 97, 54%) of which obtained recipes online. Some 69.1% (67 of 97) measured the internal temperature of the meat during dehydration, but only 10.3% (10 of 97) confirmed the internal temperature by using a thermometer. Given the paucity of information available on the fate of pathogenic or spoilage bacteria associated with meat bars, as another component of this study, batter was prepared with or without encapsulated citric acid (ECA; 0.74%) added to a formulation of ground beef (65%; 90% lean, 10% fat), chopped pecans (15%), golden flaxseed flour (9.7%), chopped cranberries (5.0%), chopped sunflower seeds (3.1%), sea salt (1.1%), black pepper (0.8%), and celery powder (0.35%). Batter was inoculated (ca. 6.5 log CFU/g) with Shiga toxin-producing Escherichia coli (STEC), portioned by hand (40 ± 0.1 g each), and then dried in a commercial dehydrator. Regardless of the drying treatment, inclusion of ECA in the batter resulted in a pH decrease from ca. 5.5 to ca. 4.7 to 5.0 in the finished product. Without ECA, when meat bars were dried at 62.8°C for 6 h, 71.1°C for 4 h, or 62.8°C for 2 h and then 71.1°C for 2 h, levels of STEC decreased by ca. 6.2, 6.3, or 5.2 log CFU/g, respectively. With ECA, STEC decreased by ca. 6.0, 6.6, or 6.0 log CFU/g in meat bars dried at 62.8°C for 6 h, 71.1°C for 4 h, or 62.8°C for 2 h and then 71.1°C for 2 h, respectively. Our results confirmed that a ≥5.0-log reduction in STEC could be achieved in meat bars formulated with or without ECA under all dehydration conditions tested.

Behavior of Listeria monocytogenes on Mortadella Formulated Using a Natural, Clean-Label Antimicrobial Agent during Extended Storage at 4 or 12°C.

All-pork mortadella, an Italian-style deli meat, was produced by a local artisanal meat producer with or without 1.0 or 1.5% liquid buffered vinegar (LBV), 0.4, 0.6, or 1.0% dry buffered vinegar (DBV), or a 2.5% blend of potassium lactate and sodium diacetate (KLac). In each of three trials, mortadella was sliced (ca. 1.5 cm thick, ca. 30 g) and surface inoculated with 250 µL per side of a five-strain mixture of Listeria monocytogenes (ca. 3.8 log CFU per slice). The packages were vacuum sealed and then stored at 4 or 12°C. In the absence of antimicrobials, L. monocytogenes levels increased by ca. 2.6 and 6.0 log CFU per slice after up to 120 or 28 days at 4 or 12°C, respectively. With inclusion of 1.0 or 1.5% LBV, 1.0% DBV, or 2.5% KLac as ingredients, pathogen levels decreased by ca. 0.3 to 0.7 log CFU per slice after 120 days at 4°C, whereas with inclusion of 0.4 or 0.6% DBV, L. monocytogenes levels increased by ca. 1.2 and 0.8 log CFU per slice, respectively. After 28 days at 12°C, inclusion of 2.5% KLac, 1.0 or 1.5% LBV, or 0.4 or 0.6% DBV resulted in a ca. 1.4- to 5.7-log increase in L. monocytogenes levels. When 1.0% DBV was included in the formulation, pathogen levels remained unchanged after 28 days at 12°C. However, product quality was lessened at this abusive storage temperature (12°C) for all treatments by the end of storage. Thus, inclusion of LBV or DBV, as clean-label ingredients, in mortadella is equally effective as KLac for controlling L. monocytogenes during storage at 4°C without adversely affecting product quality.

Use of an Electrostatic Spraying System or the Sprayed Lethality in Container Method To Deliver Antimicrobial Agents onto the Surface of Beef Subprimals To Control Shiga Toxin-Producing Escherichia coli.

The efficacy of an electrostatic spraying system (ESS) and/or the sprayed lethality in container (SLIC) method to deliver antimicrobial agents onto the surface of beef subprimals to reduce levels of Shiga toxin-producing Escherichia coli (STEC) was evaluated. Beef subprimals were surface inoculated (lean side; ca. 5.8 log CFU per subprimal) with 2 mL of an eight-strain cocktail comprising single strains of rifampin-resistant (100 µg/mL) STEC (O26:H11, O45:H2, O103:H2, O104:H4, O111:H-, O121:H19, O145:NM, and O157:H7). Next, inoculated subprimals were surface treated with lauric arginate (LAE; 1%), peroxyacetic acid (PAA; 0.025%), or cetylpyridinium chloride (CPC; 0.4%) by passing each subprimal, with the inoculated lean side facing upward, through an ESS cabinet or via SLIC. Subprimals were then vacuum packaged and stored at 4°C. One set of subprimals was sampled after an additional 2 h, 3 days, or 7 days of refrigerated storage, whereas another set was retreated via SLIC after 3 days of storage with a different one of the three antimicrobial agents (e.g., a subprimal treated with LAE on day 0 was then treated with PAA or CPE on day 3). Retreated subprimals were sampled after 2 h or 4 days of additional storage at 4°C. A single initial application of LAE, PAA, or CPC via ESS or SLIC resulted in STEC reductions of ca. 0.3 to 1.3 log CFU per subprimal after 7 days of storage. However, when subprimals were initially treated with LAE, PAA, or CPC via ESS or SLIC and then separately retreated with a different one of these antimicrobial agents via SLIC on day 3, additional STEC reductions of 0.4 to 1.0 log CFU per subprimal were observed after an additional 4 days of storage. Application of LAE, PAA, or CPC, either alone or in combination, via ESS or SLIC is effective for reducing low levels (ca. 0.3 to 1.6 log CFU) of STEC that may be naturally present on the surface of beef subprimals.