ABSTRACT
Fruit and vegetables are stored at low temperatures immediately after harvest and submitted to different postharvest treatments to control ripening and extend storage life. The enzymatic systems superoxide dismutase (SOD), catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) also play an important role in the degradation of active oxygen species and hydrogen peroxide (H2O2). Postharvest practices and technologies often produce varying degrees of oxidative stress leading to changes in the endogenous levels of antioxidants, changes in fruit ripening/senescence processes, and, finally, the development of physiological disorders. Oxygen is continuously generated within the chloroplast as a result of water oxidation by the photosynthetic electron transport chain, but concurrently removed by a series of reduction and assimilation reactions that can lead to ROS production. Plants have a complex antioxidative defense system including non-enzymatic and enzymatic components responsible for scavenging ROS.
