The antioxidant system plays a crucial role in the ripening process.
This system includes CAT, SOD, some peroxidases and the
enzymes involved in the ascorbate–glutathione cycle: APX and
GR. These enzymatic components, together with the low-molecular-
weight antioxidants ascorbic acid (AA) and glutathione (GSH),
ultimately scavenge H2O2 at the expense of NADPH or NADH
(Foyer & Halliwell, 1976). In general, all essential oil fumigation
treatments enhanced the antioxidant enzyme activities of mushrooms
compared to control (Fig. 4), in agreement with the reduced
ROS production (Fig. 3A and B). Mushrooms from cinnamaldehyde
fumigation treatment had the highest activities for APX and GR.
However, no significant differences (P > 0.05) were observed
between essential oil treatments for SOD activity. These findings
are in agreement with the results of Chanjirakul, Wang, Wang,
and Siriphanich (2006), who reported that antioxidant enzyme
activities in raspberries were increased by methyl jasmonate
treatment