QUALITY CHANGES OF BEEF STEAKS STORED IN CONTROLLED GAS ATMOSPHERES CONTAINING HIGH OR LOW-LEVELS OF OXYGEN

Steaks from bovine Longissimus and Semimembranosus muscles were used to determine the influence of gas atmospheres on beef color, microbial growth and shrinkage during 9 days of retail display in 2 separate experimental trials. Steaks were displayed in 1 of 4 gas mixtures and were compared to steaks packaged under conventional vacuum and in a film wrap. Gas mixtures containing O2 levels of 10% (1/2 ambient) did not maintain a bright red color, but those with 40-75% O2 (more than twice ambient) maintained acceptable color for 9 days of storage. Atmosphere stored steaks lost more moisture (P < 0.05) than vacuum-packaged steaks. Psychrotrophic and mesophilic microbial counts from steaks stored 9 days in atmospheres containing 15% CO2 were lower (P < 0.05) than the counts for the control steaks.