title: Influence of early postmortem protein oxidation on beef quality.
abstract: The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4 degrees C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) alpha-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness.
authors.affiliation: Animal Science Department, Iowa State University, Ames 50011, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Rowe
authors.forename: K R
authors.initials: KR
authors.lastname: Maddock
authors.forename: S M
authors.initials: SM
authors.lastname: Lonergan
authors.forename: E
authors.initials: E
authors.lastname: Huff-Lonergan
mesh_terms: D000821:Animal Feed; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle; D005511:Food Handling / Q000379:methods; D005514:Food Irradiation; D005524:Food Technology; D008297:Male; D008460:Meat / Q000592:standards*; D010084:Oxidation-Reduction; D010858:Pigmentation; D011180:Postmortem Changes; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D011786:Quality Control; D012995:Solubility; D013997:Time Factors; D014810:Vitamin E / Q000008:administration & dosage*
chemical_list: D000975:Antioxidants; D011506:Proteins; D014810:Vitamin E