Modified Atmosphere Packaging Affects Lipid Oxidation, Myofibrillar Fragmentation Index and Eating Quality of Beef

The objective of this study was to evaluate the effects of different modified atmosphere packaging (MAP) systems applied during ageing and retail display on the quality of beef longissimus dorsi. The quality of the steaks was measured by sensory analysis, thiobarbituric acid-reactive substances (TBARS), myofibrillar fragmentation index (MR), protein oxidation, weight loss, cooking loss and vitamin E content. The study included 11 different packaging systems investigated in two separate trials, using O-2, CO2, N-2 gas and vacuum in combination or alone during ageing and retail display. In some systems, loins were sliced into steaks before packaging, and in other systems, loins were vacuum packed and aged for 14-18 days, and thereafter were sliced and repacked in different atmospheres. Systems including high O-2 MAP resulted in a large increase in warmed-over flavour and in TBARS as well as a decrease in juiciness, tenderness and vitamin E content, compared to anaerobic systems. Also, MFI was lower in high O-2 MAP steaks, and an increase in protein oxidation was seen, suggesting that the decrease in meat tenderness was due to reduced proteolysis and/or protein oxidation. In addition, the cooked steaks of high O-2 MAP looked well done, although the internal temperature was only 62 degrees C, indicating premature browning. Ageing of steaks in N-2 did not affect any measured parameter compared to vacuum thermoforming packed muscle. Steaks stored in vacuum skin pack for 20 days were less tender than steaks stored in 100% N-2 for 18 days followed by 2 days in atmospheric air. In conclusion, packaging in high O-2 concentrations compromises several aspects Of meat quality. Copyright (C) 2008 John Wiley & Sons, Ltd.