Combined effect of modified atmosphere bulk packaging, dietary vitamin E supplementation and microbiological contamination on colour stability of Musculus gluteus medius

Ten Simmentaler type calves were fed diets supplemented with 500 mg vitamin E per day and ten fed control diets. After completion of a 100 day feeding period the cattle were slaughtered and rump steaks (M. gluteus medius) from each carcass PVC-overwrapped and subsequently bulk packaged in 100% CO2 or 20% CO2: 80% O2. Steaks with low levels of bacteriological contamination were also prepared and packaged. Bulk packs were stored at 4°C for 0, 14, 28 and 42 days and the PVC-overwrapped samples subsequently displayed for 0, 4 and 7 days at 4°C. After display saturation, surface metmyoglobin and oxymyoglobin accumulation of the steaks were determined and acceptability of the steaks assessed by sensory evaluation using a trained panel. The dietary vitamin E supplemented steaks were more acceptable than the steaks from cattle not supplemented with vitamin E. Steaks prepared with low levels of bacteriological contamination, supplemented with dietary vitamin E, were more acceptable and discoloured less than all the other treatments. Beef rump steaks bulk packaged in 20% CO2: 80% O2 or 100% CO2 were acceptable and colour stable for up to 14 days bulk storage at 4°C and a subsequent 2 days retail display at 4°C.