UV-C irradiation effects on levels of enzymic and non-enzymic phytochemicals in tomato

• UV-C irradiation on phytochemicals levels was investigated in tomato at 16 °C.
• Levels of water and lipid soluble antioxidants were not stimulated by UV-C.
• Maximum SOD activity in UV-C fruit was delayed by one week compared to controls.
• Total phenols were stimulated one week earlier as a result of UV-C treatment.

The study examined enzymic and non-enzymic phytochemicals in irradiated and control tomato exocarp. Mature-green tomato fruit were exposed to doses of 0, 3.7 and 24.4 kJ m− 2 UV-C radiation (254 nm) before storage at 16 °C for 28 days. Identification and quantitation of water soluble antioxidants (ascorbic acid, glutathione and cysteine) and lipid-soluble α-tocopherol were analyzed by HPLC. Spectrophotometric analysis was used to quantify total phenols and superoxide dismutase (SOD) activity.Levels of total phenols were stimulated one week earlier with both UV-C treatments compared to the control fruits. Alpha-tocopherol, ascorbic acid, glutathione and its precursor cysteine were significantly reduced with the UV-C treatment compared to controls. Maximum SOD activity in exocarp of UV-C treated fruit was delayed by one week compared to the control group.UV-C irradiation of tomato did not stimulate the accumulation of any specific phytochemicals but did stimulate the accumulation of non-specific phenols.Industrial relevanceDeveloping environmentally safe non-thermal processing technologies which are not capital intensive, in order to improve postharvest losses of tropical crops in developing countries, have always been a challenge to researchers. One such technology is the application of low dose germicidal UV-C radiation to elicit beneficial responses in tropical crops. Understanding the activation of defense mechanisms such as the production of phytochemicals as a result of UV-C irradiation can retard senescence and postharvest losses as well as provide health benefits to consumers through the consumption of fresh produce.