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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #330219

Title: Determination of protein markers for beef tenderness in U. S. select beef

item SANTOS, C - Iowa State University
item HUFF-LONERGAN, E - Iowa State University
item LONERGAN, S - Iowa State University
item Wheeler, Tommy
item Shackelford, Steven

Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/22/2016
Publication Date: 6/9/2016
Citation: Santos, C., Huff-Lonergan, E., Lonergan, S.M., Wheeler, T.L., Shackelford, S.D. 2016. Determination of protein markers for beef tenderness in U. S. select beef. [Abstract] American Meat Science Association 2016 Reciprocal Conference. June 19-22, 2016, San Angelo, TX, 2016. No. 135.

Interpretive Summary:

Technical Abstract: Objectives: Beef tenderness is a primary quality feature that defines the consumer’s perception of the product quality. Therefore definition of chemical characteristics that contribute to variation in tenderness within a specific USDA grade can help refine our understanding of meat tenderness. The objective of this experiment was to identify novel protein markers for tenderness in Longissimus dorsi sarcoplasmic fractions utilizing proteomics and a valuable library of beef samples. Materials and Methods: Steaks (USDA Select grade) used in this trial were classified as low shear force (LSF, n = 12; 11.3±1.6 kg) and high shear force (HSF, n = 12; 34.3±4.7 kg), according to their slice shear force (SSF, kg) measurements at 14 days postmortem. Western blotting of whole-muscle samples was used to determine troponin-T degradation (indicator of overall proteolysis). Sarcoplasmic protein samples from day 2 postmortem were prepared for two-dimensional difference in gel electrophoresis (2D-DIGE). Samples from LSF and HSF were sorted according to SSF values and were matched to a pooled internal reference (representative of all samples). Protein samples were loaded (75 µg) on 24 cm strips, pH 6-9, and focused in immobilized pH gradient in the first dimension. For the second dimension the strips were run on 12.5% acrylamide gels (n = 12). After 2D-DIGE, protein spots found to be different in relative abundance between HSF and LSF samples, and with other proteins of interest, were identified using Q Exactive™ Hybrid Quadrupole-Orbitrap Mass Spectrometer (LC-MS/MS). Immunoblots were performed to confirm protein identity. Results: The LSF samples exhibited greater troponin-T degradation (as evidenced by abundance of a 30 kDa fragment) than the HSF samples (LSF ratio to reference was 1.8, HSF ratio to reference was < 0.01; P < 0.01). A total of 31 spots showed a significant difference (P < 0.1) in relative abundance across groups (HSF vs. LSF). Among these, 18 spots were identified as 8 different proteins (Table 1). Proteins that were more abundant in the LSF samples are metabolic enzymes involved in the glycolytic pathway (glyceraldehyde-3-phosphate dehydrogenase, fructose bisphosphate aldolase A). Among the six proteins that showed greater abundance in the HSF samples, four belong to the oxidative energy metabolism pathways (malate dehydrogenase, creatine kinase M-type, myoglobin, carbonic anhydrase 3), one is involved in redox pathways (peroxiredoxin-1) and another one in protein turnover (polyubiquitin). The greater abundance of spots corresponding to oxidative metabolism enzymes suggests that aerobic metabolism may decrease potential for postmortem proteolysis.