Postharvest UV radiation enhanced biosynthesis of flavonoids and carotenes in bell peppers

UV abiotic stresses have beneficial effects in plants inducing the synthesis of secondary metabolites when low doses were applied. The aim of this study was to evaluate the effect of 6 kJ m−2 UV (B or C) and 6 + 6 kJ m−2 UV (B + C) on the main bioactive compounds of red bell peppers during a refrigerated shelf-life period. Changes in carotenoids, phenolics, and flavonoids were studied after 8 and 14 d at 7 °C, an after an additional retail sale period of 4 d at 18 °C. Physicochemical quality attributes were not affected by any UV treatment. Generally, UV treatments induced carotenoid accumulation, highlighting that after 14 d at 7 °C, UVB and UVC increased by 59 % the total carotenoid content, and UVB + C did it by 94 % compared to non-UV-treated peppers as control (CTRL). UVC, UVB, and UVB + C are good elicitors of the flavonoid biosynthesis with 42, 66, and 43 % increases just after treatment, respectively, compared to CTRL. This behaviour was enhanced in UVC and UVB + C treated peppers after 8 d at 7 °C (15 and 44 %, respectively) and after 14 d at 7 °C (146 and 137 %) regarding CTRL peppers, which was also shown after the retail period assayed of 4 d at 18 °C. In conclusion, a postharvest 6 kJ m-2 UV-C treatment could be a great tool for increasing the accumulation of carotenoids and flavonoids in red bell peppers.