Postmortem proteolytic and organoleptic changes in hot-boned muscle from grass- and grain-fed and zeranol-implanted cattle

• Published in: Food research international 1996-01, Vol.29 (1), p.27-34
• Main Authors: Xiong, Y.L., Moody, W.G., Blanchard, S.P., Liu, G., Burris, W.R.
• Format: Article
• Language: English
• Subjects: Animal productions; beef; Biological and medical sciences; cattle feeding; electrical stimulation; feed; feed grains; flavor; Food industries; Fundamental and applied biological sciences. Psychology; grass silage; hot boning; Meat and meat product industries; palatability; postmortem changes; proteolysis; sensory properties; Terrestrial animal productions; Vertebrates; zeranol
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/0963-9969(95)00056-9

A total of 21 yearling steers (Angus sires × crossbreed dams) were allotted to three forage management systems: (a) pasture on Johnstone fescue (G); (b) grain on grass (GG); and (c) grain on grass with zeranol implant, a growth promoter (GGP). After approximately 150 days on experiment (May to October), three randomly selected steers from each dietary group were slaughtered, and composition, sensory characteristics and proteolytic changes of semimembranosus muscle were examined during postmortem storage at 2 °C. Overall, muscle chemical composition was not affected (P> 0.05) by dietary regimen with or without the implant. Grass-fed beef had a stronger (P ≤ 0.05) grassy flavor at 2 days postmortem and developed more (P ≤ 0.05) off-flavor after 10 days of aging than grain-supplemented beef. Postmortem storage generally improved beef tenderness. The implantation did not (P> 0.05) affect weight gain nor carcass yield. However, GGP beef was more tender (P ≤ 0.05) than G and GG beef after 2 days storage; a similar trend was observed in overall beef acceptability. Proteolysis of the muscle from the three forage systems was similar in that all showed major changes beyond 2 days postmortem with the disappearance of titin and troponin-T and the appearance of a 30 kDa component being most noticeable. These results suggest postmortem differences in beef palatability among the different nutritional treatments were not closely related to muscle composition and proteolytic degradation.