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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Research Project #423446


Location: Meat Safety and Quality

2016 Annual Report

Objective 1: Develop strategies to manage and improve variation in meat quality and composition traits. 1.1: Determine the temperature and pH profiles for optimal quality of modern pork. 1.2: Develop genetic markers for pork lean color stability, tenderness, water holding capacity, intramuscular fat content, sarcomere length, and postmortem proteolysis. 1.3: Evaluation of plasma glucose and lactate levels at exsanguination as predictors of meat quality attributes. 1.4: Evaluate the relationships between mitochondrial abundance and efficiency and animal variation in beef lean color stability. 1.5: Determine seasonal variation in fatty acid profile of belly adipose from first-pull and run-out hogs fed diets differing in fatty acid profile. 1.6: Determine variation in fatty acid profile of belly fat from first-pull and run-out gilts, barrows, and immuno-castrated barrows. Objective 2: Develop non-invasive technology to improve meat quality, composition, and healthfulness traits. 2.1: Develop regression equations for prediction of ribeye (longissimus) area and other value determining characteristics using the laser-enhanced VBG2000 beef carcass grading camera. 2.2: Determine the effect of light source on robustness of regression equations for prediction of marbling score using the laser-enhanced VBG2000 beef carcass grading camera. 2.3: Develop regression equations for prediction of beef fatty acid profiles with on-line visible and near infrared (VISNIR) spectroscopic evaluation of the ribeye (longissimus) and subcutaneous fat during beef carcass grading. 2.4: Develop regression equations for on-line prediction of fatty acid profiles of pork belly fat with VISNIR spectroscopy. Objective 3: Improve product quality and healthfulness, and food animal growth and production efficiencies, through development of alternatives to conventional antimicrobials utilizing novel metagenomic and microbial genomic technologies.

The effects of the interaction of muscle pH and temperature decline on various pork quality traits will be determined. Genetic markers will be identified that can be used to optimize various pork quality traits. Plasma glucose and lactate levels at exsanguination will be evaluated as predictors of meat quality traits. Mitochondrial abundance and efficiency will be evaluated as mechanisms controlling variation in lean color stability. Season, marketing group, and immuno-castration will be investigated as sources of variation in pork fat quality. The USMARC beef carcass grading camera accuracy will be enhanced by developing prediction models using more stable light sources and laser-enhanced placement adjustments. Healthfulness and quality of beef and pork will be improved by developing visible and near-infrared prediction of fatty acid profile of lean and fat. The effect of alternatives to antibiotics such as lysozyme for young piglets on growth and efficiency will be determined. In addition, the potential for improvement of product quality and efficiency will be determined for diet modified gut microbial composition.

Progress Report
Progress under objective 1: Cured ham color is of great importance in meeting consumer expectations for ham products. Recently a condition has been identified by the meat industry where a band of very pale lean tissue is present on the outside portion of ham muscles. This pale tissue does not produce normal cured color when the muscles are processed into ham products. ARS scientists at Clay Center, Nebraska, began working with pork processors and ham processors to quantify and characterize the phenomenon. Initial efforts to quantify the occurrence of this phenomenon indicate that the condition occurs in the vast majority of pigs regardless of production system and management. Current results indicate that the pale portion of the muscle is higher in muscle pH and much lower in myoglobin concentration. These differences coincide with a significant shift in muscle fiber type towards white (glycolytic) fibers. Ongoing efforts include collaboration with a large pork processor to evaluate differing genetic lines on the incidence and severity of the condition. Moreover, a genome wide association study is underway to identify genetic markers associated with myoglobin content, which may provide a strategy to mitigate the defect. Progress under objective 1: The beef industry is continually seeking ways to improve the consistency of beef tenderness. Experiments were conducted to determine the optimum parameters for commercial implementation of a freezing process to improve tenderness and minimize water losses after thawing and aging. The first pilot lab test of freezing and thawing resulted in too much water loss after thawing. Freezing rate and extent were enhanced with dry ice freezing and resulted in significant tenderness improvement and reduced water loss after thawing, however, lean color stability of steaks during retail display from frozen and thawed top loins was severely reduced. Thus, this tenderization process may not be suitable for retail product but might be feasible for wholesale club distribution of whole subprimals. However, this process might be most suitable for foodservice product to enhance tenderness while managing seasonal fluctuations in meat prices.

1. Impact of blade tenderization on eating quality of beef top sirloin steaks. Tenderness is a critical factor affecting consumer acceptance of beef products. To ensure tenderness, purveyors use a number of strategies, of which, blade tenderization is one of the most common. Disagreement exists regarding the proper application of blade tenderization to improve tenderness without detrimental effects on other palatability traits, such as juiciness and mouth feel. ARS researchers at Clay Center, Nebraska, subjected top sirloin subprimals to treatments including: no blade tenderization, or 1, 2, or 4 passes through a blade tenderizer and then measured slice shear force (instrument tenderness). Consumers also evaluated the steaks and rated them for overall liking. Increasing the number of passes through blade tenderization progressively decreased slice shear force values, but had no effect on consumer ratings for overall liking. More than one pass through blade tenderization will not likely improve consumer satisfaction with top sirloin steaks.

2. Relationship between pork loin quality and fresh belly or fresh and processed ham quality. Through genetics and management of pigs and carcasses, the pork industry strives to improve pork quality. Much of the evaluation of product quality is based on assessment of the loin. Yet, it is uncertain whether pigs that produce high quality loins also will produce high quality hams and bellies. In collaboration with colleagues at the University of Illinois and Smithfield Foods, ARS researchers at Clay Center, Nebraska, determined that pork loin quality is not indicative of fresh belly or fresh and processed ham quality. Although statistically significant relationships existed between some primal quality traits, these correlations were weak. The lack of strong correlations may be partially due to differences in chilling among muscles. Use of loin quality to draw conclusions about belly, fresh ham, or processed ham may be misleading. To understand whole carcass quality, loin, belly, and fresh and processed ham characteristics must be evaluated individually. This finding will be used by the pork industry as it considers development of a grading system.

3. Biological basis for differences in beef tenderness among quality grade programs and packing plants. To develop strategies to control variation in tenderness, it is necessary to understand the biological basis of toughness. ARS researchers at Clay Center, Nebraska, in collaboration with the University of Wyoming determined that variation in tenderness among packing plant and quality grade programs was related to variation in muscle shortening during chilling. These findings will allow the beef industry to develop effective strategies to optimize tenderness. Ultimately, this should lead to increased consumer satisfaction and drive demand for U.S. beef.

4. The relationship between quality measurement techniques of pork loins and chops. Assessment of boneless pork loin quality under industrial conditions is used in packing plants for segregation of product into marketing programs and for identifying export product as well as for routine quality control and research. However, it was not known if this assessment is indicative of quality assessment made on pork chops, following vacuum-packaged aging of boneless loins. ARS researchers at Clay Center, Nebraska, in collaboration with Texas Tech University determined that objective color evaluation of loins under industrial conditions was highly correlated with objective color evaluation of chops from aged loins. However, subjective assessment was only moderately indicative of the difficulty in visual assessment of pork loin quality under industrial conditions. This information points to the need for objective technology for grading of pork loins in order to control quality variation in pork chops and maximize consumer satisfaction.

5. On-line prediction of pork loin quality with the VQG pork loin grading camera. The National Pork Board is considering development of a pork grading system. Grading cameras can accurately assess meat quality more consistently and reduce inherent variation in human subjective evaluation. ARS scientists at Clay Center, Nebraska, in collaboration with Texas Tech University determined that loin color, marbling, water-holding capacity, and tenderness could be predicted with on-line assessment of loins with the VQG pork loin grading camera. Implementation of this tool will allow the industry to identify higher quality pork that could be marketed in a premium program.

Review Publications
Hales, K.E., Shackelford, S.D., Wells, J., King, D.A., Pyatt, N.A., Freetly, H.C., Wheeler, T.L. 2016. Effects of dietary protein concentration and ractopamine hydrochloride on performance and carcass characteristics of finishing beef steers. Journal of Animal Science. 94(5):2097-2102. doi:10.2527/jas2015-0225
Foote, A.P., Hales, K.E., Kuehn, L.A., Keisler, D.H., King, D.A., Shackelford, S.D., Wheeler, T.L., Freetly, H.C. 2015. Relationship of leptin concentrations with feed intake, growth, and efficiency in finishing beef steers. Journal of Animal Science. 93(9):4401-4407.
Bernal Rubio, Y.L., Gualdrón Duarte, J.L., Bates, R.O., Ernst, C.W., Nonneman, D., Rohrer, G.A., King, D.A., Shackelford, S.D., Wheeler, T.L., Cantet, R.J.C., Steibel, J.P. 2015. Implementing meta-analysis from genome-wide association studies for pork quality traits. Journal of Animal Science. 93(12):5607-5617.
Boyd, B.M., Shackelford, S.D., Hales, K.E., Brown-Brandl, T.M., Bremer, M.L., Spangler, M.L., Wheeler, T.L., King, D.A., Erickson, G.E. 2015. Effects of shade and feeding zilpaterol hydrochloride to finishing steers on performance, carcass quality, heat stress, mobility, and body temperature. Journal of Animal Science. 93(12):5801-5811. doi: 10.2527/jas2015-9613.
Mckeith, R.O., King, D.A., Grayson, A.L., Shackelford, S.D., Gehring, K.B., Savell, J.W., Wheeler, T.L. 2016. Mitochondrial abundance and efficiency contribute to lean color of dark cutting beef. Meat Science. 116:165-173. doi:10.1016/j.meatsci.2016.01.016.
Grayson, A., Shackelford, S.D., King, D.A., McKeith, R., Miller, R., Wheeler, T.L. 2016. The effects of degree of dark cutting on tenderness and sensory attributes of beef. Journal of Animal Science. 94:2583-2591 doi:10.2527/jas2016-0388.