Effect of UV treatment on antioxidant capacity, antioxidant enzyme activity and decay in strawberry fruit

The changes in antioxidant capacity, enzyme activity and decay development in strawberry fruit (Fragaria x ananassa Duch.) illuminated with different UV-C dosages were investigated. Three UV-C illumination durations and dosages, 1,5 and 10 min, (0.43, 2.15 and 4.30 kJ m(-2)) tested promoted the antioxidant capacity and enzyme activities and significantly reduced the severity of decay during storage at 10 degrees C compared to the control. UV-C illumination for 5 and 10 min showed the best results tor enhancing antioxidant capacity expressed as oxygen radical absorbance capacity (ORAC) values after storage for 15 days among all the treatments. These treatments also enhanced the activities of antioxidant enzymes including glutathione peroxidase (GSH-POD), glutathione reductase (GR), superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD) guaiacol peroxidase (G-POD), monodehydroascorbate reductase (MDAR), and dehydroascorbate reductase (DHAR). The nonenzyme components such as reduced glutathione (GSH) and oxidized gultathione (GSSG) also were increased by UV-C exposure. All UV-C dosages increased the phenolic content of strawberry fruits as well. Total anthocyanin content increased during storage in all treatments. However, UV-C illumination showed little effect on the anthocyanin accumulation. All UV-C dosages retarded the development of decay comparing to control treatment, but 5 and 10 min UV-C illumination gave the best decay inhibition. (C) 2007 Elsevier B.V. All rights reserved .