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

Rohanie Maharaj, Joseph Arul and Paul Nadeau

Rohanie Maharaj

Innovative Food Science and Emerging Technologies

2014

21

PhytochemicalsPhenolsUltraviolet RadiationTomatoAlpha-TocopherolAscorbic AcidGlutathioneCysteineSuperoxide dismutase

99-106

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 ?-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 relevance Developing 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.

Completed

Elsevier