An increase in CO2 and a progressive decrease in O2 levels were also noted for the 75% O2 + 25% CO2 treatment (Fig. 2). A decrease in CO2 levels would be expected throughout the storage period due to the high solubility of this gas in refrigerated meat. However, the observed increase in the CO2 concentration can be explained by the reduction in the O2 concentration due to its consumption by the muscle respiration and due to the growing of aerobic bacteria in the meat producing CO2