Effects of UV-C irradiation on lipid peroxidation markers during ripening of tomato (Lycopersicon esculentum L.) fruits

The effects of a hormic dose (3.7 kJ m(-2)) of UV-C (254 nm) on changes in fruit membrane lipids peroxidation markers during storage were determined using tomato (Lycopersicon esculentum L. cv. Trust) fruit. There were two distinct response phases following the treatment. A significant induction of lipid peroxidation markers (lipofuscin-like compounds, malondialdehyde, aldehydes, pentane, ethane, hydrogen peroxide, and efflux of electrolytes including potassium and calcium) occurred within the first 5 days. This induction suggests that the cell membrane was the primary target of UV-C irradiation. After this period, the level of all of these peroxidation markers become lower in UV-C-treated fruit than in control fruit, suggesting the induction of a defense or repair mechanism, probably involving production of antioxidants and activation of antioxidative enzyme. Within the second phase, any changes in lipid peroxidation activity reflected the fruit ripening / senescence process rather than the UV-C effect.