Post-Harvest Use of Ultraviolet Light (UV) and Light Emitting Diode (LED) to Enhance Bioactive Compounds in Refrigerated Tomatoes.

Different strategies have been developed to increase the concentration of bioactive compounds in tomatoes during post-harvest, with ultraviolet light (UV) and light emitting diodes (LEDs) being interesting tools. The aim of this study was to evaluate the effect of ultraviolet (UVA at 366 nm and UVC at 254 nm) pre-treatment (1 kJ/m2) and red-blue LED light (25.4 µmol/m2/s) on the concentration of carotenoids, (poly)phenols and hydrophilic/lipophilic antioxidant capacity during 7 days of refrigeration storage of green tomatoes (Solanum lycopersicum L.) cultivar "Raf". In addition, special attention was paid to quality parameters (weight loss, colour, acidity, soluble solids and ripening index). Tomatoes exposed to LED light at 6 °C for 7 days increased up to three times the total carotenoids content (mainly β-carotene and E-lycopene) compared to tomatoes refrigerated in the dark, while UV treatments alone did not significantly affect the carotenoid content. Besides, exposure to LEDs increased the hydrophilic and lipophilic antioxidant capacity of tomatoes by 30%, without affecting phenolic contents. Thus, LED treatments alone during refrigerated storage fostered ripening and improved the nutritional value of tomatoes, without compromising quality parameters. Further studies must be carried out to evaluate the impact on sensory attributes and consumer acceptance.