Lipid stability and meat colour of beef from pasture- and grain-fed cattle with or without vitamin E supplement

Meat from pasture-fed cattle can have high contents of alpha -tocopherol and other anti-oxidants originating from naturally occurring compounds present in grasses. However, meat from pasture-fed cattle may have an increased demand for endogenous antioxidants because of its high content of polyunsaturated fatty acids, which in turn. tray affect its colour and lipid stability. In the work described, we evaluated the effects of pasture-feeding alone and with vitamin E supplementation and compared the findings with those obtained for grain-fed cattle (predominantly sorghum) with and without supplementation. Within each nutritional background, vitamin E supplementation did not alter meat colour or colour stability of fresh or 47-day aged muscle during 7-day aerobic storage. However, both control and supplemented grain-fed product had better meat colour (more redness) compared with meat from grass-fed cattle. These differences in redness between pasture- and grain-fed fresh beef were not apparent after ageing. The treatments did not affect the lipid stability of fresh meat during aerobic storage; however, supplementation reduced (P < 0.01) lipid oxidation in grain-fed aged beef compared with pasture-fed aged beef, despite both having similar alpha -tocopherol contents. Pasture-fed beef had more linolenic acid, less linoleic acid and, overall, was more polyunsaturated than grain-fed beef (P < 0.05). In summary, vitamin E supplementation of pasture-fed cattle did not alter muscle tocopherol contents but pasture-fed beef (both control and supplemented) wits more susceptible to lipid oxidation following ageing than vitamin E supplemented grain-fed beef. (C) 2001 Elsevier Science Ltd. All rights reserved.