Journal of Food Research; Vol. 3, No. 2; 2014 ISSN 1927-0887 E-ISSN 1927-0895 Published by Canadian Center of Science and Education 61 Role of the Physical Elicitors in Enhancing Postharvest Antioxidant Capacity of Table Grape cv Redglobe (Vitis vinifera L.) Pasquale Crupi 1 , Arianna Pichierri 1 , Rosa Anna Milella 1 , Rocco Perniola 1 & Donato Antonacci 1 1 CRA - Consiglio per la Ricerca e la sperimentazione in Agricoltura - Unità di ricerca per l’uva da tavola e la vitivinicoltura in ambiente mediterraneo, Italy Correspondence: Donato Antonacci, CRA - Consiglio per la Ricerca e la sperimentazione in Agricoltura - Unità di ricerca per l’uva da tavola e la vitivinicoltura in ambiente mediterraneo, Italy. Tel: 39-080-891-5711. E-mail: donato.antonacci@entecra.it Received: October 28, 2013 Accepted: February 10, 2014 Online Published: February 17, 2014 doi:10.5539/jfr.v3n2p61 URL: http://dx.doi.org/10.5539/jfr.v3n2p61 Abstract 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. Keywords: physical elicitors, UV-C, polyphenols, anthocyanins, ORAC 1. Introduction The grape consumption has been associated with multiple beneficial health effects mainly due to the polyphenol content in this fruit (Cook & Samman, 1996; Teissendre et al., 1996). Phenolics are secondary metabolites that are widely distributed in the plant kingdom. Typically in Vitis vinifera they are present as flavonoids, comprising flavanols, anthocyanins and flavan-3-ols, and non-flavonoids, comprising hydroxybenzoic acids, hydroxycinnamic acids and stilbenes (Glories, 1998). Numerous studies have established that total anthocyanins as well as phenolic concentrations are positively related to the total antioxidant activity (Wang, Cao, & Prior, 1997; Meyers, Watkins, Pritts, & Liu, 2003; Sun, Chu, Wu, & Liu, 2002). Recently, due to health awareness campaigns, consumers have become more and more interested in foods that support and promote health which are characterized by high health-promoting compound content rather than having superior external quality attributes, as was previously the case. Therefore, to meet this shift in consumer needs the use of postharvest elicitors, that can promote the levels of phytochemicals in postharvest crops, has become an area of key interest (Goldmann, Kader, & Heintz, 1999; Huyskens-Keil & Schreiner, 2004). It is known that quantitative and qualitative pattern of polyphenols depends on the developing stage of a plant, which means that by selecting the harvest time it is possible to obtain products with different flavonoid profiles. Generally, in order to improve the elicitor’s effect on the accumulation of phenols during the postharvest stage, fruit and vegetables should be harvested at optimum maturity (Schreiner & Huyskens-Keil, 2006; Terry & Joyce, 2004). The storage process can modify the content of phenolic acids and flavonoids in the plant material, leading to an increase or decrease which depend on the storage conditions, such as temperature and time, but also