Changes in Glutathione, Ascorbate, and Antioxidant Enzymes during Olive Fruit Ripening

The content of glutathione, ascorbate (ASC), and the enzymatic antioxidants, superoxide dismutase and catalase, and components of the ascorbate–glutathione cycle were investigated in the olive fruit (cv. Picual) selected at the green, turning, and mature ripening stages. The changes observed in total and reduced glutathione (GSH), oxidized glutathione (GSSG), the ratio GSH/GSSG, ASC, and antioxidant enzymes (mainly superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) indicate a shift to a moderate cellular oxidative status during ripening and suggest a role for antioxidants in the process. The antioxidant composition of olive oils obtained from the olive fruits of the study was investigated. A model is proposed for the recycling of antioxidant polyphenols mediated by endogenous molecular antioxidants in the olive fruit.