Role of the Physical Elicitors in Enhancing Postharvest Antioxidant Capacity of Table Grape cv Redglobe (Vitis vinifera L.)

Polyphenols, such as anthocyanins, are secondary metabolites produced in plants which can play an important health-promoting role considering their strong correlation with antioxidant capacity. The biosynthesis of these compounds generally increases as a response to biotic or abiotic stress, therefore, in order to achieve as high phenolic accumulation as possible, the interactive effects of storage conditions (temperature and time) and postharvest ultraviolet irradiation (UV-C) on total polyphenols (TPP) and total anthocyanins (TA) content, as well as oxygen radical antioxidant capacity (ORAC), in postharvest “Redglobe” table grape variety were investigated in 2011 vintage. Gathered findings showed that UV-C exposure ranging from 1 to 3 min (0.8-2.4 KJ m-2) positively influence the TA level (with an increase almost twice higher than the control) during a storage time longer than 48 h, independently from the storage temperature; while, with regard to TPP and ORAC, a progressive increment of their values (roughly from 2 to 4 folds higher than the control) up to 120 h of storage was observed, in particular in Redglobe grapes irradiated for 1 min and stored at 4 °C. Responding to the rising consumers needs to have foods that support and promote health, this research demonstrated that the postharvest simultaneous application of physical elicitors can lead to grapes with enhanced antioxidant properties, within normal conditions of market commercialization. The practical relevance of this finding is evident considering that grapes are economically the most important fruit species in the world and approximately 30% of its production is used as fresh fruit.