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Efficacy of sulfuric acid sodium sulfate on inoculated populations of Salmonella spp. and Campylobacter spp. on pork subprimals, and its effects on natural spoilage microflora, lean discoloration and off-odors




McCullough, Kathryn Rose, author
Belk, Keith, advisor
Morley, Paul, committee member
Delmore, Robert, committee member
Yang, Hua, committee member

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Salmonella and Campylobacter are pathogens commonly associated with foodborne illness. As these pathogens are often found in fresh pork, efforts to reduce or eliminate them is imperative to the pork industry. Additionally, fresh pork is highly perishable and maintenance of desirable attributes is imperative. So, extending shelf life of fresh pork is important to maintain profitability and desirability of product. Although a variety of attributes can determine pork shelf-life, reducing spoilage microflora is an important quality control point. Therefore, this study was conducted to determine efficacy of applying sulfuric acid sodium sulfate (SA) to reduce inoculated populations of Salmonella spp. and Campylobacter spp. on pork subprimals. Additionally, this study aimed to determine efficacy of SA application against inoculated populations of non-pathogenic Escherichia coli that could then serve as surrogates for Salmonella spp. and Campylobacter spp. on pork in in-plant trials (Experiment 1). This study also was conducted to determine effects of a SA spray on the natural spoilage microflora, off odor characteristics, and discoloration properties of pork subprimals during vacuum storage and simulated retail display (Experiment 2). And, SA was evaluated in a commercial pork in-plant system against the natural microflora and inoculated populations of a surrogate bacteria (Experiment 3). For Experiment 1, vacuum packaged pork subprimals were obtained from a local retailer less than 10 days postmortem. Entire subprimals were cut into uniform sample pieces and assigned to one of the following treatments: 1.0 pH SA, 1.5 pH SA, water or an untreated control. Samples were inoculated to a target level of 6 logs CFU/g for Salmonella spp. and surrogate E. coli, or 5.5 logs CFU/g for Campylobacter spp., with cocktails before treatment. Surviving pathogen and non-pathogenic E. coli populations were determined at 5 minutes post- treatment and at 24 h post-treatment. For Experiment 2, boneless pork loins and bone-in backribs were obtained from a commercial pork processing facility and treated with a topical spray of SA at 1.5 pH, 1.0 pH, or an untreated control. After treatment, all samples were placed in dark, refrigerated storage for 14 d or 21 d, after which one half of the samples were removed from storage, overwrapped with polyvinyl chloride film, and placed into retail display cases maintained at 4°C (±2°C) for up to 96 h. At 12 h intervals for the duration of simulated retail display, trained panelists evaluated percent discoloration. Additionally, at 0, 48 and 96 h of display, trained panelists evaluated intensity of off odors and plated and enumerated populations of Psychrotrophic, Pseudomonas, Lactic acid bacteria and yeast and molds. For Experiment 3, 60 carcasses were railed off and market strategically with 5 x 10 cm2 areas. Half the zones were inoculated with the surrogate bacteria, the other half remained uninocualted. Carcasses were then treated with the SA using a commercial application spray cabinet. For Experiment 1, application of 1.0 pH SA was the most effective (P < 0.05) at reducing inoculated populations of both Salmonella spp, and Campylobacter spp, compared to all other treatments. However, no difference (P > 0.05) was observed for Campylobacter and surrogate bacterial populations determined at 5 min versus populations at 24 h. Additionally, non-pathogenic E. coli strains were affected less by treatment than inoculated Salmonella spp. and Campylobacter spp.populations and can, therefore, effectively serve as surrogates for Salmonella spp. and Campylobacter spp. For Experiment 2, after 14 and 21 d of dark storage, both boneless loins and backribs sprayed with 1.0 pH SA had lower (P < 0.05) Psychrotrophic, Pseudomonas, Lactic acid bacteria and yeast and mold populations than control or 1.5-pH treated samples at 0, 48 and 96 h of display. Percent discoloration of boneless loin chops increased over the duration of retail display for products stored for 14 and 21 d before simulated retail display. Boneless loin chops treated with 1.0 pH SA had a greater percent discoloration at each simulated retail display test time than untreated chops or those sprayed with 1.5 pH SA. For Experiment 3, SA proved to effectively lower (P < 0.05) both inoculated and uninoculated bacterial (TPC, EB, TCC, and ECC) populations on pork carcasses. However, treatment with 1.0 pH SA was more effective than treatment with 1.3 pH SA.


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sulfuric acid sodium sulfate
storage life


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