Changes in color, antioxidant, and free radical scavenging enzyme activity of mushrooms under high oxygen modified atmospheres

The effects of high oxygen concentration (80% O-2) on color, antioxidant enzyme and free radical scavenging activity of mushrooms (Agaricus bisporus) were investigated. High oxygen modified atmosphere chambers were designed. Mushrooms (A. bisporus) were held at 2 degrees C for 12d in modified atmosphere chambers, linked by separate lines to continuous flow (1.67 mLs(-1)) of humidified air (control) and 80% O-2 (balance N-2). Browning of mushroom flesh and surface exposed to 80% O-2 was prevented and the expected increase in membrane permeability and lipid peroxidation was delayed. Compared to the control treatment, high oxygen significantly inhibited the reactive oxygen species (ROS) such as O-2(center dot-) and H2O2. The corresponding oxygen radical scavenging enzyme activities including SOD, CAT and POD in 80% O-2 were also higher than those in the control (P < 0.05). Higher antioxidant activity was found in high oxygen treated mushrooms. The treatment with 80% O-2 could be used in modified atmosphere of mushrooms to avoid browning, which was due to enhanced antioxidant and free radical scavenging enzyme activity. (C) 2012 Elsevier B.V. All rights reserved.