To evaluate the effect of extended post-harvest hanging time on pork carcass sides (n = 20), aerobic plate count (APC), Enterobacteriaceae, yeast and mold populations, pH, and moisture content were determined. Pork carcasses were sampled on d 1, 7, 14, and 21 to determine their microbial quality from the lean tissue of 3 anatomical locations, the flank, shoulder, and jowl. After the 21-d extended hanging time, pork shoulder butts (n = 17) (Institutional Meat Purchase Specifications #406; USDA Agricultural Marketing Service, 2014) were fabricated from these carcasses into 2.54-cm pork blade steaks. Pork blade steaks were vacuum packaged, stored up to 35 d at 0°C ± 1°C, and evaluated for APC, Enterobacteriaceae, yeast and mold populations, and pH on d 0, 7, 14, 21, 28, and 35. Pork carcass surface moisture content declined (P < 0.01) from 65.1% on d 1 to 50.5% on d 21. The carcass pH was similar (P > 0.42) at 5.88 on d 1, 7, and 14; however, the pH declined (P < 0.05) to 5.72 at d 21. Pork carcass APC populations remained relatively low during the extended hanging time; however, the jowl had the highest (P < 0.05) APC populations among all anatomical locations. In addition, the proportion of yeast populations above the detection limit for the jowl was found to be greatest (P < 0.05) compared to the flank and the shoulder. Pork blade steak APC population was 5.06 log colony-forming units/g (CFU/g) on d 35; however, these counts were below 108 log CFU/g, which is when meat is considered spoiled. There was a day effect for Enterobacteriaceae and mold populations (P < 0.05). These results indicate that pork carcasses and vacuum-packaged steaks fabricated from pork carcasses have acceptable microbial quality when they undergo an extended hanging time.

The effectiveness of a recently invented "steam pasteurization" (S) process in reducing pathogenic bacterial populations on surfaces of freshly slaughtered beef was determined and compared with that of other standard commercial methods including knife trimming (T), water washing (35°C; W), hot water/steam vacuum spot cleaning (V), and spraying with 2% vol/vol lactic acid (54°C, pH 2.25; L). These decontamination treatments were tested individually and in combinations. Cutaneus trunci muscles from freshly slaughtered steers were inoculated with feces containing Listeria monocytogenes Scott A, Escherichia coli OI57:H7, and Salmonella typhimurium over a predesignated meat surface area, resulting in initial populations of ca. 5 log CFU/cm2 of each pathogen. Tissue samples were excised from each portion before and after decontamination treatments, and mean population reductions were determined. Treatment combinations evaluated were the following (treatment designations within the abbreviations indicate the order of application): TW, TWS, WS, VW, VWS, TWLS, and VWLS. These combinations resulted in reductions ranging from 3.5 to 5.3 log CFU/cm2 in all three pathogen populations. The TW, TWS, WS, TWLS, and VWLS combinations were equally effective (P > 0.05), resulting in reductions ranging from 4.2 to 5.3 log CFU/cm2. When used individually, T, V, and S resulted in pathogen reductions ranging from 2.5 to 3.7 log CFU/cm2 Steam pasteurization consistently provided numerically greater pathogen reductions than T or V. Treatments T, V, and S were all more effective than W (which gave a reduction on the order of 1.0 log CFU/cm2). Steam pasteurization is an effective method for reducing pathogenic bacterial populations on surfaces of freshly slaughtered beef, with multiple decontamination procedures providing greatest overall reductions.

The effects of extrusion cooking alone or in combination with electron beam radiation (3.5 kGy) on vacuum-packaged beef-based snack sticks containing beef cardiac muscle were investigated. During formulation, Clostridium sporogenes PA 3679 spores were added to achieve a concentration of 4 log CFU/g. Twin-screw extrusion cooking at 72°C reduced aerobic plate counts (APCs) by 3.63 log cycles and C. sporogenes viable cell counts by 2.02 log cycles for the inoculated product. After irradiation (3.5 kGy), APCs were decreased to 1 log CFU/g when compared to 0 kGy counterparts receiving 0 kGy. Spores were not detected in irradiated inoculated samples, which contained C. sporogenes PA 3679 at levels of 3.17 to 3.50 log CFU/g after extrusion cooking.

This research evaluated the effectiveness of a newly patented steam-pasteurization process for reducing bacterial populations on the surfaces of freshly slaughtered beef carcasses. The process was developed jointly by Frigoscandia Food Processing Systems (Bellevue, WA) and Excel Corp. (Wichita, KS), a division of Cargill (Minneapolis, MN). In laboratory studies, portions of prerigor beef carcasses inoculated with very high levels of three pathogens, Salmonella, Escherichia coli O157:H7, and Listeria, were treated in a prototype steam-pasteurization chamber, which effectively eliminated at least 99.9% of all three pathogens and was most effective when used in combination with other standard commercial decontamination methods. The effectiveness of a full-scale, automated, steam-pasteurization system was evaluated in a commercial beef slaughter facility. The commercial system was very effective, reducing the naturally occurring overall bacterial population by over 90% and reducing the population of E. coli (nonpathogenic) and related organisms to undetectable levels. Steam pasteurization is very effective at reducing bacterial contamination on unchilled beef carcasses and should be viewed as one step in an overall process of reducing the risk of pathogenic bacteria in beef and beef products.