ABSTRACT
The effectiveness of a steam pasteurization process for reducing naturally occurring bacterial populations on freshly slaughtered beef sides was evaluated in a large commercial facility. Over a period of 10 days, 140 randomly chosen beef sides were microbiologically analyzed. Each side was sampled immediately before, immediately after, and 24 h after steam pasteurization treatment. Total aerobic bacteria (APC), Escherichia coli (generic), coliform, and Enterobacteriaceae populations were enumerated. The process significantly (P ≤ 0.01) reduced mean APCs from 2.19 log CFU/cm2 before treatment to 0.84 log CFU/cm2 immediately after and 0.94 log CFU/cm2 24 h after treatment. Before pasteurization (8 s steam exposure), 16.4% of carcasses were positive for generic E. coli (level of 0.60 to 1.53 log CFU/cm2), 37.9% were positive for coliforms (level of 0.60 to 2.26 log CFU/cm2), and 46.4% were positive for Enterobacteriaceae (level of 0.60 to 2.25 log CFU/cm2). After pasteurization, 0% of carcasses were positive for E. coli , 1.4% were positive for coliforms (level of 0.60 to 1.53 log CFU/cm2), and 2.9% were positive for Enterobacteriaceae (level of 0.60 to 1.99 log CFU/cm2). Of the 140 carcasses evaluated, one carcass was positive for Salmonella spp. before treatment (0.7% incidence rate); all carcasses were negative after steam treatment. This study indicates that steam pasteurization is very effective in a commercial setting for reducing overall bacterial populations on freshly slaughtered beef carcasses. The system may effectively serve as an important critical control point for HACCP systems at the slaughter phase of beef processing. In conjunction with other antimicrobial interventions (mandated by USDA to achieve zero tolerance standards for visible contamination) and good manufacturing practices, this process can play an important role in reducing the risk of pathogenic bacteria in raw meat and meat products.
ABSTRACT
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.
