The malondialdehyde (MDA) level was determined as 2-thiobarbituric acid (TBA) reactive metabolites according to the procedure adopted Zhou and Leul (1998). Mushroom cup tissue(0.2 g) was homogenized and extracted in 10 mL of 0.25% TBA madein 10% trichloroacetic acid (TCA). The extract was heated at 95◦C for30 min and then cooled on ice. After ice cooling, the samples were centrifuged at 6000 × g for 10 min. The absorbance of supernatant was measured at 532 nm by spectrophotometer. The correctionof non-specific turbidity was made by subtracting the absorbancevalue taken at 600 nm. The quantity of MDA was expressed on afresh weight basis in mol kg−1of protein by using an extinction coefficient of 15.5 mol m−1