Alleviation of chilling injury in postharvest tomato fruit by preconditioning with ultraviolet irradiation.

BACKGROUND: Tomato fruit is usually stored at low temperatures for delayed ripening and extended shelf life. However, tomato fruit is susceptible to chilling injury when exposed to low temperatures. In this study, the potential effects of preconditioning with UV-C or UV-B irradiation on chilling injury of postharvest tomato fruit were investigated.

RESULTS: Mature-green tomato fruit were exposed to 4 kJ m(-2) UV-C or 20 kJ m(-2) UV-B irradiation and stored for 20 days at 2 °C and subsequently 10 days at 20 °C. UV irradiation was effective in reducing chilling injury index and delaying ethylene peak. Furthermore, UV irradiation preserved storage quality as manifested by reduced weight loss, better retention of firmness, and higher contents of total soluble solids, soluble protein and soluble sugar during subsequent storage at 20 °C. UV-C irradiation significantly delayed the development of the red colour after 10 days of storage at 20 °C. On the other hand, UV irradiation decreased total phenolics content and antioxidant capacity, suggesting possibly reduced stress response to low temperature resulted from enhanced physiological adaptation by UV preconditioning.

CONCLUSION: Our results suggest that preconditioning with UV-C or UV-B irradiation in appropriate doses had a positive effect on alleviating chilling injury in postharvest tomato fruit.