Effect of preharvest selenium sprays on antioxidant properties of Fakhri grape raisins(Vitis vinifera cv Fakhri)

Raisins are dried grapes that obtained from different cultivars of Vitis vinifera L. and are rich sources of a wide type of polyphenols that are considered particularly interesting for their beneficial properties in human health. Selenium as a rare non- metal element due to the high antioxidant properties in trace amounts is necessary for cellular function in many plant and human organisms. The objective of the present study was to evaluate the effect of exogenous selenium treatment on antioxidant properties of Fakhri grape raisins. The vines were sprayed with selenium (selenat) concentrations at 0 (control), 1, 2 and 3 mg/L at three stage of berry growth (1-Berry set 2-Lage phase, 3-Veraison). Fruits were harvested at commercial maturity stage and dried under sun s shade conditions. Some traits such as selenium content, DPPH radical scavenging activity, total phenolic and flavonoid content were raisins evaluated. The results showed that raisins produced from grapes pre-harvest treated with 3 mg/L of selenat had more antioxidant activity, total phenolics, and flavonoids content. The highest amount of internal selenium content in raisins was obtained in 2 mg/L of selenat treatment. Our results indicated that selenium could enhance raisins antioxidant activity and pre-harvest treatment with selenium can be proposed as a novel technique to improve the quality of grapes and raisins

Keywords:

Fruit selenium , Selenat , Total flavonoid , Total phenol