Abbey L. Nutsch

Evaluation of a steam pasteurization process in a commercial beef processing facility

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.

Steam pasteurization of commercially slaughtered beef carcasses: Evaluation of bacterial populations at five anatomical locations

A steam pasteurization process (patent pending) has been shown to effectively reduce pathogenic bacterial populations on beef tissue and to significantly reduce naturally occurring bacterial populations on commercially slaughtered beef carcasses. The objective of this study was to determine the effectiveness of the steam pasteurization treatment for reducing bacterial populations at several anatomical locations on commerically slaughtered carcasses. Before and after pasteurization treatment (82.2 degrees C, 6.5-s exposure time), a sterile sponge was used to sample 300 cm2 at one of five locations (inside round, loin, midline, brisket, or neck). Eighty carcasses (40 before treatment and 40 after treatment) were sampled per anatomical location over 2 processing days. Before treatment, aerobic plate counts (APCs) were found to be highest (P < or = 0.01) at the midline (4.5 log10 CFU/100 cm2), intermediate at the inside round, brisket, and neck (ca. 3.8 log10 CFU/100 cm2), and lowest at the loin (3.4 log10 CFU/100 cm2). After treatment, APCs at all locations were reduced significantly (P < or = 0.01). The inside round, loin, and brisket had the lowest (P < or = 0.01) APCs (ca. 2.6 log10 CFU/100 cm2), whereas the midline and neck had APCs of 3.1 and 3.3 log10 CFU/100 cm2, respectively. The lower reduction in APCs at the neck area indicated that the treatment may not be as effective there, possibly because of the design of the pasteurization equipment. Generic Escherichia coli populations were low at all locations before treatment, with populations on 32% of all carcasses sampled being less than the detection limit of the study (5.0 CFU/100 cm2). After treatment, E. coli populations were significantly lower (P < or = 0.01) than populations before treatment and 85% of all carcasses sampled had E. coli populations below the detection limit. The maximum E. coli population detected after treatment was 25 CFU/100 cm2. For enteric bacterial populations, no differences were observed in the effectiveness of the treatment among the five carcass locations.

A survey of castration methods and associated livestock management practices performed by bovine veterinarians in the United States

BackgroundCastration of male calves destined for beef production is a common management practice performed in the United States amounting to approximately 15 million procedures per year. Societal concern about the moral and ethical treatment of animals is increasing. Therefore, production agriculture is faced with the challenge of formulating animal welfare policies relating to routine management practices such as castration. To enable the livestock industry to effectively respond to these challenges there is a need for more data on management practices that are commonly used in cattle production systems. The objective of this survey was to describe castration methods, adverse events and husbandry procedures performed by U.S. veterinarians at the time of castration. Invitations to participate in the survey were sent to email addresses of 1,669 members of the American Association of Bovine Practitioners and 303 members of the Academy of Veterinary Consultants.ResultsAfter partially completed surveys and missing data were omitted, 189 responses were included in the analysis. Surgical castration with a scalpel followed by testicular removal by twisting (calves <90 kg) or an emasculator (calves >90 kg) was the most common method of castration used. The potential risk of injury to the operator, size of the calf, handling facilities and experience with the technique were the most important considerations used to determine the method of castration used. Swelling, stiffness and increased lying time were the most prevalent adverse events observed following castration. One in five practitioners report using an analgesic or local anesthetic at the time of castration. Approximately 90% of respondents indicated that they vaccinate and dehorn calves at the time of castration. Over half the respondents use disinfectants, prophylactic antimicrobials and tetanus toxoid to reduce complications following castration.ConclusionsThe results of this survey describe current methods of castration and associated management practices employed by bovine veterinarians in the U.S. Such data are needed to guide future animal well-being research, the outcomes of which can be used to develop industry-relevant welfare guidelines.

Validation of a Traditional Italian-Style Salami Manufacturing Process for Control of Salmonella and Listeria monocytogenes†

Italian-style salami batter (formulated with pork shoulder) was inoculated with ca. 7.0 log CFU/g of either Salmonella or Listeria monocytogenes. Salami links (55-mm cellulose casings) were fermented at 30 degrees C for 24, 40, or 72 h and then dried to target moisture/protein ratios (MPRs) of 1.9:1 or 1.4:1. Links were sampled after fermentation (24, 40, and 72 h) and after combined fermentation-drying treatments (MPRs of 1.9:1 and 1.4:1 for all fermentation periods), and microbiological and proximate analyses were performed at each sampling. Pathogen populations were enumerated by direct plating on selective agar and by an injured-cell recovery method. When enumerated by the injured-cell recovery method, Salmonella populations were reduced by 1.2 to 2.1 log CFU/g after fermentation alone (24 to 72 h) and by 2.4 to 3.4 log CFU/g when fermentation was followed by drying. Drying to an MPR of 1.4:1 was no more effective than drying to an MPR of 1.9:1 (P > 0.05). When enumerated directly on selective media, Salmonella populations were reduced from 1.6 to 2.4 log CFU/g and from 3.6 to 4.5 log CFU/g for fermentation alone and fermentation followed by drying, respectively. L. monocytogenes populations were reduced by <1.0 log CFU/g following all fermentation and combined fermentation-drying treatments, regardless of the enumeration method. These results suggest that the Italian-style salami manufacturing process evaluated does not adequately reduce high pathogen loads. Processors may thus need to consider supplemental measures, such as raw material specifications and a final heating step, to enhance the lethality of the overall manufacturing process.

Effectiveness of a laboratory-scale vertical tower static chamber steam pasteurization unit against Escherichia coli O157 :H7, Salmonella Typhimurium, and Listeria innocua on prerigor beef tissue

A laboratory-scale vertical tower steam pasteurization unit was evaluated to determine the antimicrobial effectiveness of different exposure times (0, 3, 6, 12, and 15 s) and steam chamber temperatures (82.2, 87.8, 93.3, and 98.9 degrees C) against pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria innocua) inoculated onto prerigor beef tissue. Samples were collected and microbiologically analyzed immediately before and after steam treatment to quantify the effectiveness of each time-temperature combination. The 0-s exposure at all chamber temperatures (cold water spray only, no steam treatment) was the experimental control and provided < or = 0.3 log CFU/cm2 reductions. Chamber temperatures of 82.2 and 87.8 degrees C were ineffective (P > 0.05) at all exposure times. At 93.3 degrees C, significant reductions (> 1.0 log CFU/cm2) were observed at exposure times of > or = 6 s, with 15 s providing approximately 1 log cycle greater reductions than 12 s of exposure. The 98.9 degrees C treatment was consistently the most effective, with exposure times of > or = 9 s resulting in >3.5 log CFU/cm2 reductions for all pathogens.

Antimicrobial activity of cetylpyridinium chloride against Listeria monocytogenes on frankfurters and subsequent effect on quality attributes

Frankfurters inoculated with Listeria monocytogenes were treated with 1% cetylpyridinium chloride (CPC) or with 1% CPC followed by a water rinse at various combinations of spray temperatures (25, 40, and 55 degrees C), spray pressures (20, 25, and 35 psi), and times of exposure (30, 40, and 60 s). No significant differences (P > 0.05) were observed in the reductions achieved by 1% CPC + water wash and those achieved with 1% CPC treatment alone. L. monocytogenes populations were reduced by ca. 1.7 log CFU/g immediately following treatment, with no differences (P > 0.05) observed for different spray temperatures, pressures, or exposure times. The effectiveness of 1% CPC spray treatment (at 25 degrees C, 20 psi, and 30 s of exposure) against L. monocytogenes on vacuum-packaged frankfurters stored at 0 and 4 degrees C for 42 days was then evaluated. Application of a 1% CPC surface spray to frankfurters immediately prior to packaging reduced L. monocytogenes concentrations by 1.4 to 1.7 log CFU/g and further restricted growth of the pathogen during 42 days of refrigerated storage, thereby meeting U.S. Department of Agriculture alternatives 1 and 2 criteria for Listeria control. CPC treatment reduced aerobic plate counts, lactic acid bacteria, yeasts and molds, total coliforms, and Escherichia coli populations on noninoculated frankfurters to below detectable limits. The 1% CPC treatment did not affect the color (L*, a*, and b* values) of frankfurters stored for 42 days at 0 or 4 degrees C (P > 0.05). The effect of 1% CPC treatment on the firmness of frankfurters was also negligible.

Efficacy of cetylpyridinium chloride against Listeria monocytogenes and its influence on color and texture of cooked roast beef.

Sliced (cut) and exterior (intact) surfaces of restructured cooked roast beef were inoculated with Listeria monocytogenes, treated with cetylpyridinium chloride (CPC; immersion in 500 ml of 1% solution for 1 min), individually vacuum packaged, and stored for 42 days at 0 or 4 degrees C. Noninoculated samples were similarly treated, packaged, and stored to determine effects on quality (color and firmness) and on naturally occurring bacterial populations, including aerobic plate counts and lactic acid bacteria. Immediately after CPC treatment, regardless of inoculation level, L. monocytogenes populations were reduced (P = 0.05) by about 2 log CFU/cm2 on sliced surfaces and by about 4 log CFU/cm2 on exterior surfaces. Throughout 42 days of refrigerated storage (at both 0 and 4 degrees C), L. monocytogenes populations on CPC-treated samples remained lower (P = 0.05) than those of nontreated samples for both surface types. After 42 days of storage at both 0 and 4 degrees C, aerobic plate count and lactic acid bacteria populations of treated samples were 1 to 1.5 log CFU/cm2 lower (P = 0.05) than those of nontreated samples for both surface types. CPC treatment resulted in negligible effects (P > 0.05) on the color (L*, a*, and b* values) of exterior and sliced roast beef surfaces during storage. For both sliced and exterior surfaces, CPC-treated samples were generally less firm than nontreated samples. CPC treatment effectively reduced L. monocytogenes populations on roast beef surfaces and resulted in relatively minor impacts on color and texture attributes. CPC treatment, especially when applied to products prior to slicing, may serve as an effective antimicrobial intervention for ready-to-eat meat products.

Primary care physicians and pandemic influenza: An appraisal of the 1918 experience and an assessment of contemporary planning

This multidisciplinary research project examined the role of primary care physicians in past pandemic flu responses and current planning efforts. Project researchers gathered and synthesized historical research, state and federal planning documents, and interview-based data. The 1918 influenza pandemic presented one model from which to understand the role played by physicians during a large-scale disease outbreak, and the challenges they faced. Contemporary planning documents were assessed for their inclusion of primary care physicians. Literature reviews and interviews comprised the principal sources of information. Findings included the following: (1) primary care physicians do not have the time to engage fully in pandemic planning activities; (2) physicians are willing to serve during a pandemic; however, government support and the availability of resources will affect their level of involvement; (3) communities should develop plans for coordinating local physicians who will allow alternative care sites to be functionally staffed; and (4) full coordination of physicians is not possible under the US healthcare system.

Comparing the mannitol-egg yolk-polymyxin agar plating method with the three-tube most-probable-number method for enumeration of Bacillus cereus spores in raw and high-temperature, short-time pasteurized milk.

The U.S. Food and Drug Administrations Bacteriological Analytical Manual recommends two enumeration methods for Bacillus cereus: (i) standard plate count method with mannitol-egg yolk-polymyxin (MYP) agar and (ii) a most-probable-number (MPN) method with tryptic soy broth (TSB) supplemented with 0.1% polymyxin sulfate. This study compared the effectiveness of MYP and MPN methods for detecting and enumerating B. cereus in raw and high-temperature, short-time pasteurized skim (0.5%), 2%, and whole (3.5%) bovine milk stored at 4°C for 96 h. Each milk sample was inoculated with B. cereus EZ-Spores and sampled at 0, 48, and 96 h after inoculation. There were no differences (P > 0.05) in B. cereus populations among sampling times for all milk types, so data were pooled to obtain overall mean values for each treatment. The overall B. cereus population mean of pooled sampling times for the MPN method (2.59 log CFU/ml) was greater (P < 0.05) than that for the MYP plate count method (1.89 log CFU/ml). B. cereus populations in the inoculated milk samples ranged from 2.36 to 3.46 and 2.66 to 3.58 log CFU/ml for inoculated milk treatments for the MYP plate count and MPN methods, respectively, which is below the level necessary for toxin production. The MPN method recovered more B. cereus, which makes it useful for validation research. However, the MYP plate count method for enumeration of B. cereus also had advantages, including its ease of use and faster time to results (2 versus 5 days for MPN).

Steam pasteurization to reduce bacterial populations on commercially slaughtered beef carcasses

A steam pasteurization system (SPS) has been shown in laboratory and commercial evaluations to effectively reduce bacterial populations on freshly slaughtered beef. Our study evaluate d the bactericidal uniformity of SPS. Samples were collected from the five anatomical locations, one per carcass, 40 samples per location , so that 200 carcasses were evaluated before and 200 after pasteurization. Each carcass was sampled by wiping a 300 c m2 area of the specified location with a moist, sterile sponge. For all locations, the total aerobic plate count (APC) after pasteurization was lower (P#.01). Before pasteurization, the midline was contaminate d most heavily (2.5 log10 cfu/cm2 ). After pasteurization, the neck and midline had the highest residual APCs (1.3 and 1.1 log 10 cfu/cm2, respectively). For all anatomical locations, the enteric bacteria (E. coli, total coliform, an d Enterobacteriaceae ) were lower (P#.01) after than before pasteurization. Only two of 200 pasteurized carcasses ha d E. coli populations greater than 1 cfu/cm2. During pasteurization, steam blankets the carcasses, theoretically providing uniform bacterial destruction. This study demonstrated the effectiveness of SPS for reducing total aerobic and enteric bacterial populations uniformly over five anatomical locations on commercially processed carcasses.