Changes in reactive oxygen species production and antioxidant enzyme activity of Agaricus bisporus harvested at different stages of maturity

BACKGROUND: The edible mushroom Agaricus bisporus is more prone to senescence than most other vegetables. However, the senescence of A. bisporus before harvesting is often ignored. In this study the changes in reactive oxygen species (ROS) production and antioxidant enzyme activity of A. bisporus harvested at four different stages of maturity were investigated. RESULTS: The firmness of A. bisporus decreased from 6.22 to 5.12 N. Respiration rate increased from 540.65 to 609.82 mg CO2 kg⁻¹ fresh weight (FW) h⁻¹. Browning degree increased from 0.42 to 0.71, showing a positive correlation with polyphenol oxidase activity. For ROS production, superoxide radical production rate increased from 0.51 to 1.16 nmol g⁻¹ FW s⁻¹. Hydrogen peroxide content increased from 0.81 to 1.39 nmol g⁻¹ FW and then decreased rapidly to 0.68 nmol g⁻¹ FW. Malondialdehyde content increased from 1.58 to 2.64 nmol g⁻¹ FW. For antioxidant enzymes, superoxide dismutase and peroxidase activities decreased significantly at stage 4, whereas a significant increase in catalase activity was found at stages 3 and 4. CONCLUSIONS: The balance between ROS and antioxidants was destroyed at stage 4, causing extensive senescence of mushroom tissues. Thus A. bisporus should be harvested at stage 3.