J. Anim Sci.
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J. Anim Sci. 1987. 64:171-176.
© 1987 American Society of Animal Science
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Fragmentation Index as an Early Postmortem Predictor of Beef Tenderness1

R. R. Hawkins2, G. W. Davis2, J. K. Cable, Jr.3 and C. B. Ramsey2

Texas Tech University, Lubbock 79409

Abstract

Short loins were removed from 36 Holstein (Group I) and 41 Brahman crossbred (Brahman-X) and Hereford steer carcasses (Group II) to study fragmentation index (FI) as an early postmortem (PM) measure of tenderness of beef carcasses and among breeds. Simple correlation coefficients between FI of raw muscle (Group I) and shear-force value (SFV) for cooked loin steaks were .51, .48 and .52 for samples of longissimus muscle aged 24, 48 and 240 h, respectively. When the Hereford and Brahman-X carcasses were pooled (n = 41), SFV of cooked loin steaks was related to USDA quality grade (r = -.46), tenderness estimate by evaluator A, r = -.55, FI at 36 h PM (r = .54) and FI at 240 h PM (r = .52). For Group II carcasses, FI at 36 h PM explained an additional 19.5% of the variation in cooked loin-steak tenderness after fat thickness, hot carcass weight and USDA quality grade factors were included in the regression model. Fragmentation index accounted for 26.4% and 19.5% more of the variation in shear-force value, above the use of all carcass traits, of cooked loin steaks from Holstein and combined Brahman-X and Hereford steers, respectively. Differences in meat tenderness largely are due to muscle protein, and most likely FI is measuring a stromal and(or) myofibrillar protein contribution to tenderness, not related to the aging of muscle proteins. Fragmentation index of raw longissimus muscle at 24 or 36 h PM alone or in conjunction with other carcass measures is a useful tooi in early PM prediction of beef tenderness.

Footnotes

1 Texas Tech Univ., College of Agr. Sci. Manuscript No. T-5-209.

2 Dept. of Anim. Sci.

3 Present address: Agr. Bldg., Univ. of Missouri, Columbia, MO 65211.






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Copyright © 1987 by the American Society of Animal Science.