Factors Associated with Tenderness of Three Beef Muscles

Tenderness is the prominent quality determinant and probably the most important sensory characteristic of beef steak and roast meat. Currently postmortem aging (storage of carcass at refrigerated temperatures for 8 to 14 days) appears to be the best method for producing tender meat. Although the improvement in meat tenderness as a result of postmortem aging is measurable both subjectively and objectively, the exact mechanism responsible for this improvement in tenderness is unknown. It is well known that different muscles within the same carcass react differently to postmortem storage; for example, tenderloin is tender to begin with and does not improve significantly with postmortem storage, while ribeye is the toughest muscle initially and improves greatly with postmortem storage. The purpose of these experiments was to attempt to answer the following questions: 1)Why are some muscles (e.g., tenderloin) tender at 24 hr postmortem and nonresponsive to postmortem aging? and 2) Why do some muscles (e.g., ribeye and tenderloin) respond differently to postmortem aging

Factors Associated with Tenderness of Three Beef Muscles

Tenderness is the prominent quality determinant and probably the most important sensory characteristic of beef steak and roast meat. Currently postmortem aging (storage of carcass at refrigerated temperatures for 8 to 14 days) appears to be the best method for producing tender meat. Although the improvement in meat tenderness as a result of postmortem aging is measurable both subjectively and objectively, the exact mechanism responsible for this improvement in tenderness is unknown. It is well known that different muscles within the same carcass react differently to postmortem storage; for example, tenderloin is tender to begin with and does not improve significantly with postmortem storage, while ribeye is the toughest muscle initially and improves greatly with postmortem storage. The purpose of these experiments was to attempt to answer the following questions: 1)Why are some muscles (e.g., tenderloin) tender at 24 hr postmortem and nonresponsive to postmortem aging? and 2) Why do some muscles (e.g., ribeye and tenderloin) respond differently to postmortem aging

Valuing Fed Cattle Using Objective Tenderness Measures

Beef tenderness is critical in consumer satisfaction with beef steak products. Current fed cattle valuation systems do not differentiate carcasses based upon tenderness variation. However, considerable research indicates consumers are willing to pay more for tender relative to tough beef steak. This article develops a tenderness-augmentation to current fed cattle grid pricing systems. Using a large set of actual carcasses, we determine that a tenderness-augmented price grid would reorder fed cattle value by on average nearly $5.00/cwt dressed relative to current valuation methods. Substantial opportunity is present to improve beef tenderness through new price signals to producers.beef quality, meat tenderness, cattle value, cattle price, Agribusiness, Farm Management, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries, Q11, Q13, M31,

Efficacy of Hypobromous Acid as a Hide-On Carcass Antimicrobial Intervention

Escherichia coli O157:H7 and Salmonella on cattle hides at slaughter are the main source of beef carcass contamination by these foodborne pathogens during processing. Hypobromous acid (HOBr) has been approved for various applications in meat processing, but the efficacy of HOBr as a hide antimicrobial has not been determined. In this study, the antimicrobial properties of HOBr were determined by spraying cattle hides at either of two concentrations, 220 or 500 ppm. Treatment of hides with 220 ppm of HOBr reduced the prevalence of E. coli O157:H7 on hides from 25.3 to 10.1% (P , 0.05) and reduced the prevalence of Salmonella from 28.3 to 7.1% (P \u3c 0.05). Treatment of hides with 500 ppm of HOBr reduced (P , 0.05) the prevalence of E. coli O157:H7 on hides from 21.2 to 10.1% and the prevalence of Salmonella from 33.3 to 8.1%. The application of 220 ppm of HOBr reduced (P \u3c 0.05) aerobic plate counts, total coliform counts, and E. coli counts on hides by 2.2 log CFU/100 cm2. The use of 500 ppm of HOBr resulted in reductions (P \u3c 0.05) of aerobic plate counts, total coliform counts, and E. coli counts by 3.3, 3.7, and 3.8 log CFU/100 cm2, respectively, demonstrating that the use of higher concentrations of HOBr on hides resulted in additional antimicrobial activity. These results indicate that the adoption of a HOBr hide wash will reduce hide concentrations of spoilage bacteria and pathogen prevalence, resulting in a lower risk of carcass contamination

Efficacy of Hypobromous Acid as a Hide-On Carcass Antimicrobial Intervention

Escherichia coli O157:H7 and Salmonella on cattle hides at slaughter are the main source of beef carcass contamination by these foodborne pathogens during processing. Hypobromous acid (HOBr) has been approved for various applications in meat processing, but the efficacy of HOBr as a hide antimicrobial has not been determined. In this study, the antimicrobial properties of HOBr were determined by spraying cattle hides at either of two concentrations, 220 or 500 ppm. Treatment of hides with 220 ppm of HOBr reduced the prevalence of E. coli O157:H7 on hides from 25.3 to 10.1% (P , 0.05) and reduced the prevalence of Salmonella from 28.3 to 7.1% (P \u3c 0.05). Treatment of hides with 500 ppm of HOBr reduced (P , 0.05) the prevalence of E. coli O157:H7 on hides from 21.2 to 10.1% and the prevalence of Salmonella from 33.3 to 8.1%. The application of 220 ppm of HOBr reduced (P \u3c 0.05) aerobic plate counts, total coliform counts, and E. coli counts on hides by 2.2 log CFU/100 cm2. The use of 500 ppm of HOBr resulted in reductions (P \u3c 0.05) of aerobic plate counts, total coliform counts, and E. coli counts by 3.3, 3.7, and 3.8 log CFU/100 cm2, respectively, demonstrating that the use of higher concentrations of HOBr on hides resulted in additional antimicrobial activity. These results indicate that the adoption of a HOBr hide wash will reduce hide concentrations of spoilage bacteria and pathogen prevalence, resulting in a lower risk of carcass contamination

Distribution of \u3ci\u3eEscherichia coli\u3c/i\u3e Passaged through Processing Equipment during Ground Beef Production Using Inoculated Trimmings

The contamination of raw ground beef by Escherichia coli O157:H7 is not only a public health issue but also an economic concern to meat processors. When E. coli O157:H7 is detected in a ground beef sample, the product lots made immediately before and after the lot represented by the positive sample are discarded or diverted to lethality treatment. However, there is little data to base decisions on how much product must be diverted. Therefore, five 2,000-lb (907-kg) combo bins of beef trimmings were processed into 10-lb (4.54-kg) chubs of raw ground beef, wherein the second combo of meat was contaminated with a green fluorescent protein (GFP)–expressing strain of E. coli. This was performed at two different commercial ground beef processing facilities, and at a third establishment where ground beef chubs from the second grinding establishment were mechanically split and repackaged into 3-lb (1.36-kg) loaves in trays. The GFP E. coli was tracked through the production of 10-lb (4.54-kg) chubs and the strain could not be detected after 26.5% more material (500 lb or 227 kg) and 87.8% more material (1,840 lb or 835 kg) followed the contaminated combo at each establishment, respectively. Three-pound (1.36-kg) loaves were no longer positive after just 8.6% more initially noncontaminated material (72 lb or 33 kg) was processed. The GFP strain could not be detected postprocessing in any residual meat or fat collected from the equipment used in the three trials. These results indicate that diversion to a safe end point (lethality or rendering) of the positive lot of ground beef, plus the lot before and lot after should remove contaminated ground beef, and as such provides support for the current industry practice. Further, the distribution and flow of E. coli on beef trimmings through various commercial equipment was different; thus, each establishment needs to consider this data when segregating lots of ground beef and establishing sampling protocols to monitor production

Comparisons of \u3ci\u3eBos indicus\u3c/i\u3e and \u3ci\u3eBos taurus\u3c/i\u3e Inheritance for Carcass Beef Characteristics and Meat Palatability

Crossbreeding is used widely to exploit heterosis and additive genetic variation among breeds to improve efficiency of beef production. The economic value of Bos indicus breeds of cattle, primarily Brahman, in crossbreeding programs in subtropical and tropical climates has been well established. In the temperate climatic conditions of U.S. Meat Animal Research Center, productivity of Bos indicus x Bos taurus F1 crossbred cows has been outstanding for reproduction an matemal performance relative to that of Bos taurus x Bos taurus F1 cross cows when mated to produce terminal-cross calves by Red Poll or Simmental sires. (Brahman and Sahiwal are Bos indicus [humped] breeds; Pinzgauer, Angus, Hereford, Red Poll and Simmental and other European breeds are Bos taurus [nonhumped] breeds)

Temporal Response of Rabbits to β-Adrenergic Agonist Feeding: Tissue Weight, Calpains and Calpastatin Activities, and Nucleic Acid and Protein Concentrations

Forty-eight crossbred rabbits were used in three replications of a 2 x 4 factorial arrangement to investigate the short-term responses of tissue accretion, calpains and calpastatin activity, and nucleic acid and protein concentrations to β- adrenergic agonist (BAA) feeding. Rabbits were fed a 17% CP diet with or without 7 ppm of L644,969 and slaughtered after 1, 4, 8, or 16 d of treatment. Empty body dressing percentage and biceps femoris weight (as a percentage of empty body weight [EBWI) were significantly higher in the treated rabbits than in the controls after 16 d of treatment. Heart and liver weights (as a percentage of EBW) were higher ( P \u3c .05) after 1 d and liver weight (as a percentage of EBW) was lower (P \u3c .05) after 16 d in treated vs controls. Except for an elevation of skeletal muscle m-calpain after 16 d, BAA-supplementation did not affect the calpain-calpastatin system. Muscle RNA concentrations and RNA:DNA ratios were higher (P \u3c .05) in treated rabbits after 1 d and remained higher thereafter. Protein:RNA ratios were lower ( P \u3c .0 1) in treated than in control rabbits after 4 d and remained lower throughout the trial. Muscle DNA content was lower after 4 d and higher after 16 d; RNA content was higher after 4, 8, and 16 d; and protein content was higher after 16 d in treated vs control rabbits. Liver nucleic acid and protein concentrations were not affected by BAA treatment. Heart RNA:DNA ratios were higher ( P \u3c .0 1) after 1 d and protein:RNA ratios were lower (P \u3c .05) after 4 d in the treated rabbits than in the controls. Collectively, these data imply that BAA-induced muscle growth in rabbits occurs through hyperplasia and seems to be related to elevated protein synthetic capacity

Supplementary data for article: Nastasijevic, I.; Schmidt, J. W.; Boskovic, M.; Glisic, M.; Kalchayanand, N.; Shackelford, S. D.; Wheeler, T. L.; Koohmaraie, M.; Bosilevac, J. M. Seasonal Prevalence of Shiga Toxin-Producing Escherichia Coli on Pork Carcasses for Three Steps of the Harvest Process at Two Commercial Processing Plants in the United States. Appl. Environ. Microbiol. 2020, 87 (1). https://doi.org/10.1128/AEM.01711-20.

Supplementary material for: [https://doi.org/10.1128/AEM.01711-20]Related to published version: [https://vet-erinar.vet.bg.ac.rs/handle/123456789/2029

Seasonal Prevalence of Shiga Toxin-Producing Escherichia coli on Pork Carcasses for Three Steps of the Harvest Process at Two Commercial Processing Plants in the United States

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that has a significant impact on public health, with strains possessing the attachment factor intimin referred to as enterohemorrhagic E. coli (EHEC) and associated with life-threatening illnesses. Cattle and beef are considered typical sources of STEC, but their presence in pork products is a growing concern. Therefore, carcasses (n = 1,536) at two U.S. pork processors were sampled once per season at three stages of harvest (poststunning skins, postscald carcasses, and chilled carcasses) and then examined using PCR for Shiga toxin genes (stx), intimin genes (eae), aerobic plate count (APC), and Enterobacteriaceae counts (EBC). The prevalence of stx on skins, postscald, and chilled carcasses was 85.3, 17.5, and 5.4%, respectively, with 82.3, 7.8, and 1.7% of swabs, respectively, having stx and eae present. All stx-positive samples were subjected to culture isolation that resulted in 368 STEC and 46 EHEC isolates. The most frequently identified STEC were serogroups O121, O8, and O91 (63, 6.7, and 6.0% of total STEC, respectively). The most frequently isolated EHEC was serotype O157:H7 (63% of total EHEC). Results showed that scalding significantly reduced (P 75%) cases of severe illnesses caused by STEC and are considered adulterants of beef. However, some STEC outbreaks have been attributed to pork products, although the same E. coli are not considered adulterants in pork because little is known of their prevalence along the pork chain. The significance of the work presented here is that it identifies disease-causing STEC, EHEC, demonstrating that these same organisms are a food safety hazard in pork as well as beef. The results show that most STEC isolated from pork are not likely to cause severe disease in humans and that processes used in pork harvest, such as scalding, offer a significant control point to reduce contamination. The results will assist the pork processing industry and regulatory agencies to optimize interventions to improve the safety of pork products.Supplementary material: [https://vet-erinar.vet.bg.ac.rs/handle/123456789/2030]This is the peer-reviewed version of the following article: Nastasijevic, I.; Schmidt, J. W.; Boskovic, M.; Glisic, M.; Kalchayanand, N.; Shackelford, S. D.; Wheeler, T. L.; Koohmaraie, M.; Bosilevac, J. M. Seasonal Prevalence of Shiga Toxin-Producing Escherichia Coli on Pork Carcasses for Three Steps of the Harvest Process at Two Commercial Processing Plants in the United States. Appl. Environ. Microbiol. 2020, 87 (1). [https://doi.org/10.1128/AEM.01711-20