Effect of electrical stimulation, delayed chilling and post-mortem aging on the quality of M. longissimus dorsi and M. biceps femoris of grass-fed steers

BACKGROUND: Roughage-based low-input beef production systems are gaining increasing interest owing to the perceived ecological advantages and potential health benefits associated with the favourable fatty acid composition of such beef. The low plane of nutrition may on the other hand yield less tender beef by affecting growth, carcass weight and fatness and therefore, indirectly, early post-mortem (p.m.) proteolytic enzyme activity and sarcomere shortening. This study aimed to examine delayed chilling and electrical stimulation as promising techniques to control early p.m. muscle metabolism in a way that improves the tenderness of beef from purely grass-fed steers in comparison with that from steers receiving a finishing diet with concentrates.RESULTS: Electrical stimulation decreased the pH at 1.5 and 3 h p.m. in the M. longissimus dorsi (LD) and M. biceps femoris (BF) of the treated carcass sides as well as the maximum shear force in the LD, while delayed chilling had no effect on pH or texture. The interactions of carcass fatness with electrical stimulation (P = 0.025) and delayed chilling (P = 0.089) indicated more pronounced effects of the p.m. treatments on beef texture in leaner carcasses.CONCLUSION: Electrical stimulation, but not delayed chilling, could markedly improve pasture beef texture and reduce the aging period needed for proper tenderisation. Copyright © 2008 Society of Chemical Industry