J. W. Savell

Comparison of Methods for Decontamination from Beef Carcass Surfaces

Methods for the removal of fecal contamination from beef carcass surfaces were evaluated using a fecal suspension containing a rifampicin-resistant strain of either Escherichia coli O157:H7 or Salmonella typhimurium . Paired cuts from four distinct beef carcass regions (inside round, outside round, brisket, and clod) were removed from hot carcasses after splitting, and subcutaneous fat and lean carcass surfaces from these cuts were used to model decontamination of prechilled carcass surface regions. Hot carcass surface regions were contaminated with an inoculated fecal suspension in a 400-cm2 area and then treated by one of four treatments either immediately or 20 to 30 min after contamination. One paired contaminated surface region from each carcass side was trimmed of all visible fecal contamination. The remaining paired carcass surface region was washed either with water (35°C) or with water followed by a 2% lactic or acetic acid spray (55°C). Surface samples were obtained for microbiological examination before and after treatment from within and outside the defined area contaminated with the fecal suspension. All treatments significantly reduced levels of pathogens; however, decontamination was significantly affected by carcass surface region. The inside round region was the most difficult carcass surface to decontaminate, regardless of treatment. Washing followed by organic acid treatment performed better than trimming or washing alone on all carcass region surfaces except the inside round, where organic acid treatments and trimming performed equally well. Overall, lactic acid reduced levels of E. coli O157:H7 significantly better than acetic acid; however, differences between the abilities of the acids to reduce Salmonella were less pronounced. All treatments caused minimal spread of pathogens outside the initial area of fecal contamination, and recovery after spreading was reduced by organic acid treatments.

Comparison of water wash, trimming, and combined hot water and lactic acid treatments for reducing bacteria of fecal origin on beef carcasses

Cleaning treatments, such as high-pressure water wash at 35 degrees C or trim, alone and combined with sanitizing treatments, such as hot water (95 degrees C at the source), warm (55 degrees C) 2% lactic acid spray, and combinations of these two sanitizing methods, were compared for their effectiveness in reducing inoculated numbers (5.0 to 6.0 log CFU/cm2) of Salmonella typhimurium, Escherichia coli O157:H7, aerobic plate counts, Enterobacteriaceae, total coliforms, thermotolerant coliforms, and generic E. coli on hot beef carcass surface areas in a model carcass spray cabinet. Log reductions in numbers of all tested organisms by water wash or trim alone were significantly smaller than the log reductions obtained by the different combined treatments. Regardless of the cleaning treatment (water wash or trim) or surface area, the range for mean log reductions by hot water was from 4.0 to > 4.8 log CFU/cm2, by lactic acid spray was from 4.6 to > 4.9 log CFU/cm2, by hot water followed by lactic acid spray was from 4.5 to > 4.9 log CFU/cm2, and by lactic acid spray followed by hot water was from 4.4 to > 4.6 log CFU/cm2, for S. typhimurium and E. coli O157:H7. Identical reductions were obtained for thermotolerant coliforms and generic E. coli. No differences in bacterial reductions were observed for different carcass surface regions. Water wash and trim treatments caused spreading of the contamination to other areas of the carcass surface while providing an overall reduction in fecal or pathogenic contamination on carcass surface areas. This relocated contamination after either water wash or trim was most effectively reduced by following with hot water and then lactic acid spray. This combined treatment yielded 0% positive samples for S. typhimurium, E. coli O157:H7, thermotolerant coliforms, and generic E. coli on areas outside the inoculated areas, whereas percent positive samples after applying other combined treatments ranged from 22 to 44% for S. typhimurium, 0 to 44% for E. coli O157:H7, and 11 to 33% for both thermotolerant coliforms and generic E. coli. From data collected in this study, it is possible to choose an effective, inexpensive treatment to reduce bacterial contamination on beef carcasses. In addition, the similar reduction rates of total coliforms, thermotolerant coliforms, or generic E. coli may be useful in identifying an indicator to verify the effectiveness of the selected treatment as a critical control point in a Hazard Analysis and Critical Control Point program.

Use of hot water for beef carcass decontamination

Hot water treatment of beef carcass surfaces for reduction of Escherichia coli O157:H7, Salmonella typhimurium, and various indicator organisms was studied using a model carcass spray cabinet. Paired hot carcass surface regions with different external fat characteristics (inside round, outside round, brisket, flank, and clod) were removed from carcasses immediately after the slaughter and dressing process. All cuts were inoculated with bovine feces containing 10(6)/g each of rifampicin-resistant E. coli O157:H7 and S. typhimurium, or with uninoculated bovine feces. Surfaces then were exposed to a carcass water wash or a water wash followed by hot water spray (95 degrees C). Counts of rifampicin-resistant Salmonella and E. coli or aerobic plate count (APC) and coliform counts were conducted before and after each treatment. All treatments significantly reduced levels of pathogens from the initial inoculation level of 5.0 log(10) CFU/cm2. Treatments including hot water sprays provided mean reductions of initial counts for E. coli O157:H7 and S. typhimurium of 3.7 and 3.8 log, APC reductions of 2.9 log, and coliform and thermotolerant coliform count reductions of 3.3 log. The efficacy of hot water treatments was affected by the carcass surface region, but not by delaying the treatment (30 min) after contaminating the surface. Verification of efficacy of hot water interventions used as critical control points in a hazard analysis critical control point (HACCP) system may be possible using coliform counts.

Factors influencing the variation in tenderness of seven major beef muscles from three Angus and Brahman breed crosses.

Beef carcasses (n=30) from 3/4 Angus (A)×1/4 Brahman (B), 1/4A×3/4B, and 1/2A×1/2B F(1) crosses were used to evaluate breed type, electrical stimulation, and postmortem aging on the M. semimembranosus (SM), M. semitendinosus (ST), M. biceps femoris (BF), M. vastus lateralis (VL), M. gluteus medius (GM), M. longissimus dorsi lumborum (LD), and M. triceps brachii (TB). Shear force values decreased with increased postmortem aging to a greater extent in steaks from 3/4A×1/4B than steaks from the other breed types. Shear force values for steaks from the round (SM, ST, BF, VL) were higher than steaks from the loin (LD, GM) and chuck (TB) for both electrically stimulated and non-electrically stimulated muscles. In the LD muscle, calpastatin activities were similar among breed types. Muscle type played the greatest role in determining tenderness.

Decontamination of Beef Carcass Surface Tissue by Steam Vacuuming Alone and Combined with Hot Water and Lactic Acid Sprays

Hot beef carcass surface regions (outside round, brisket, and clod) contaminated with feces spread over a 5-cm2 (1-in2) area were cleaned using a steam-vacuum spot-cleaning system alone or combined with subsequent sanitizing treatments of hot water (95 degrees C at the nozzle), or warm (55 degrees C) 2% lactic acid spray, or combinations of these two sanitizing methods. These treatments were compared for effectiveness in reducing aerobic plate counts (APC) and counts of Enterobacteriaceae, total coliforms, thermotolerant coliforms, and Escherichia coli. All treatments significantly reduced the numbers of each group of bacteria on beef carcass surfaces. However, reductions obtained by steam vacuuming were significantly smaller than those obtained by a combination of steam vacuuming with any sanitizing treatment. No differences in bacterial reductions were observed between different carcass surface regions. Steam vacuuming reduced the number of different indicator organisms tested by ca. 3.0 log cycles but also spread the bacterial contamination to areas of the carcass surface adjacent to the contaminated sites. This relocated contamination after steam vacuuming was most effectively reduced by spraying with hot water and then lactic acid. This combined treatment consistently reduced the numbers of Enterobacteriaceae, total and thermotolerant coliforms, and E. coli to undetectable levels (<1.0 log10 CFU/cm2) on areas outside the initial 5-cm2 inoculated areas.

Evaluation of peroxyacetic acid as a post-chilling intervention for control of Escherichia coli O157:H7 and Salmonella Typhimurium on beef carcass surfaces.

Four experiments were conducted to test the efficacy of peroxyacetic acid as a microbial intervention on beef carcass surfaces. In these experiments, beef carcass surfaces were inoculated with fecal material (no pathogens) or fecal material containing rifampicin-resistant Escherichia coli O157:H7 and Salmonella Typhimurium. Inoculated surfaces were subjected to a simulated carcass wash with and without 2% l-lactic acid treatment before chilling. In Experiments 1 and 2, the chilled carcass surfaces were sprayed with peroxyacetic acid (200 ppm; 43°) for 15 s. Peroxyacetic acid had no effect on microbial counts of any organism measured on these carcass surfaces. However, lactic acid reduced counts of E. coli Type I (1.9log(10) CFU/cm(2)), coliforms (3.0log(10) CFU/cm(2)), E. coli O157:H7 (2.7log(10) CFU/cm(2)), and S. Typhimurium (2.8log(10) CFU/cm(2)) entering the chilling cooler and prevented growth during the chilling period. In Experiment 3, peroxyacetic acid at different concentrations (200, 600, and 1000 ppm) and application temperatures (45 and 55 °C) were used to investigate its effectiveness in killing E. coli O157:H7 and S. Typhimurium compared to 4% l-lactic acid (55 °C). Application temperature did not affect the counts of either microorganism. Peroxyacetic acid concentrations up to 600 ppm had no effect on these microorganisms. Concentrations of 1000 ppm reduced E. coli O157:H7 and S. Typhimurium by up to 1.7 and 1.3log(10) CFU/cm(2), respectively. However, 4% lactic acid reduced these organisms by 2.7 and 3.4log(10) CFU/cm(2), respectively. In Experiment 4, peroxyacetic acid (200 ppm; 43 °C) was applied to hot carcass surfaces. This treatment caused a 0.7log(10) CFU/cm(2) reduction in both E. coli O157:H7 and S. Typhimurium. The collective results from these experiments indicate that peroxyacetic acid was not an effective intervention when applied to chilled inoculated carcass piece surfaces.

Microbiological effects of acid decontamination of beef carcasses at various locations in processing

Hot (55°C), dilute (1% v/v) lactic acid was sprayed on beef carcass surfaces immediately after dehiding, after evisceration (immediately before chilling), or at both locations. Surface samples of carcasses were examined for total aerobic plate counts (APCs) and for the presence of Salmonella and Listeria . APCs of treated beef carcasses were lower (P<0.05) than those of control carcasses. APCs were determined both at slaughter day 0 (immediately after carcasses enter the chill room) and after 72 h postmortem. At day 0, reductions in log10 APC by more than 90% occurred when carcasses were treated with lactic acid after evisceration or both after dehiding and after evisceration. The effect of lactic acid decontamination was greatest on carcasses treated with lactic acid both after dehiding and after evisceration. No further reductions in APCs of carcasses were observed on samples taken 72 h postmortem. No difference in color between control and acid-treated carcasses was observed. All samples tested for the presence of Salmonella were negative. Listeria was detected in three samples from control carcasses only. Samples obtained from strip loins of acid-treated or control carcasses did not show any consistent pattern of differences in microbiological counts. Additional data collected from carcasses sprayed with lactic acid in three different sized slaughter plants showed that irrespective of differences in size of slaughter facility, mean APCs of acid-treated carcasses were significantly (P<0.05) lower than those of control carcasses.

NATIONAL BEEF QUALITY AUDIT-2011: IN-PLANT SURVEY OF TARGETED CARCASS CHARACTERISTICS RELATED TO QUALITY, QUANTITY, VALUE, AND MARKETING OF FED STEERS AND HEIFERS

The 2011 National Beef Quality Audit (NBQA-2011) assessed the current status of quality and consistency of fed steers and heifers. Beef carcasses (n = 9,802), representing approximately 10% of each production lot in 28 beef processing facilities, were selected randomly for the survey. Carcass evaluation for the cooler assessment of this study revealed the following traits and frequencies: sex classes of steer (63.5%), heifer (36.4%), cow (0.1%), and bullock (0.03%); dark cutters (3.2%); blood splash (0.3%); yellow fat (0.1%); calloused rib eye (0.05%); overall maturities of A (92.8%), B (6.0%), and C or greater (1.2%); estimated breed types of native (88.3%), dairy type (9.9%), and Bos indicus (1.8%); and country of origin of United States (97.7%), Mexico (1.8%), and Canada (0.5%). Certified or marketing program frequencies were age and source verified (10.7%), ≤A(40) (10.0%), Certified Angus Beef (9.3%), Top Choice (4.1%), natural (0.6%), and Non-Hormone-Treated Cattle (0.5%); no organic programs were observed. Mean USDA yield grade (YG) traits were USDA YG (2.9), HCW (374.0 kg), adjusted fat thickness (1.3 cm), LM area (88.8 cm2), and KPH (2.3%). Frequencies of USDA YG distributions were YG 1, 12.4%; YG 2, 41.0%; YG 3, 36.3%; YG 4, 8.6%; and YG 5, 1.6%. Mean USDA quality grade (QG) traits were USDA quality grade (Select(93)), marbling score (Small(40)), overall maturity (A(59)), lean maturity (A(54)), and skeletal maturity (A(62)). Frequencies of USDA QG distributions were Prime, 2.1%; Choice, 58.9%; Select, 32.6%; and Standard or less, 6.3%. Marbling score distribution was Slightly Abundant or greater, 2.3%; Moderate, 5.0%; Modest, 17.3%; Small, 39.7%; Slight, 34.6%; and Traces or less, 1.1%. Carcasses with QG of Select or greater and YG 3 or less represented 85.1% of the sample. This is the fifth benchmark study measuring targeted carcass characteristics, and information from this survey will continue to help drive progress in the beef industry. Results will be used in extension and educational programs as teaching tools to inform beef producers and industry professionals of the current state of the U.S. beef industry.

National Beef Tenderness Survey–2010: Warner-Bratzler shear force values and sensory panel ratings for beef steaks from United States retail and food service establishments

The tenderness and palatability of retail and food service beef steaks from across the United States (12 cities for retail, 5 cities for food service) were evaluated using Warner-Bratzler shear (WBS) and consumer sensory panels. Subprimal postfabrication storage or aging times at retail establishments averaged 20.5 d with a range of 1 to 358 d, whereas postfabrication times at the food service level revealed an average time of 28.1 d with a range of 9 to 67 d. Approximately 64% of retail steaks were labeled with a packer/processor or store brand. For retail, top blade had among the lowest (P < 0.05) WBS values, whereas steaks from the round had the greatest (P < 0.05) values. There were no differences (P > 0.05) in WBS values between moist-heat and dry-heat cookery methods for the top round and bottom round steaks or between enhanced (contained salt or phosphate solution) or nonenhanced steaks. Food service top loin and rib eye steaks had the lowest (P < 0.05) WBS values compared with top sirloin steaks. Retail top blade steaks and food service top loin steaks received among the greatest (P < 0.05) consumer sensory panel ratings compared with the other steaks evaluated. Prime food service rib eye steaks received the greatest ratings (P < 0.05) for overall like, like tenderness, tenderness level, like juiciness, and juiciness level, whereas ungraded rib eye steaks received the lowest ratings (P < 0.05) for like tenderness and tenderness level. The WBS values for food service steaks were greater (P < 0.05) for the Select and ungraded groups compared with the Prime, Top Choice, and Low Choice groups. The WBS values and sensory ratings were comparable to the last survey, signifying that no recent or substantive changes in tenderness have occurred.

Decontamination of cattle hides prior to slaughter using washes with and without antimicrobial agents.

Two trials were conducted to determine the efficacy of cattle wash treatments in reducing pathogens on hides of cattle before slaughter. In trial I, live cattle (n = 120) were washed in an automated, commercial cattle wash system with one of four treatments (single water wash, double water wash, water wash with 0.5% L-lactic acid, or water wash with 50 ppm chlorine). Samples were collected at three locations (brisket, belly, and inside round) pre- and posttreatment to evaluate the effectiveness of treatments on the reduction of aerobic plate counts, coliforms, Escherichia coli and the incidence of Salmonella. For all three locations, bacterial numbers increased from 0.1 to 0.8 log CFU/cm2 posttreatment. In trial II, hide samples were inoculated in the laboratory with 6.0 log CFU/cm2 of rifampicin-resistant Salmonella serotype Typhimurium. Hide wash treatments included higher concentrations of chlorine (100, 200, and 400 ppm) and L-lactic acid (2, 4, and 6%), as well as other antimicrobial agents such as ethanol (70, 80, and 90%), acetic acid (2, 4, and 6%), and Oxy-Sept 333 (0.5, 2, and 4%). Spray wash treatments with ethanol and 4 to 6% concentrations of lactic acid had greater (P < 0.05) mean log reductions than 2% solutions of acetic or lactic acid, as well as 100, 200, and 400 ppm chlorine and the control water wash treatment. Spray wash treatments with Oxy-Sept 333 and 100, 200, or 400 ppm chlorine were not effective (P > 0.05) in reducing Salmonella Typhimurium compared to the (control) distilled water spray wash treatment. Several effective cattle hide interventions were identified in a controlled laboratory setting, but the high concentrations required for effectiveness would likely present problems from an animal welfare standpoint.