EFFECT OF SOLVENT TYPE ON THE ANTIOXIDANT POTENTIAL OF ULTRASONIC EXTRACTS OF IRANIAN GRAPE VARIETIES

Abstract

There is limited information on the antioxidant potential of Iranian grape varieties. Due to the very high consumption of grape varieties in Iran and their export, it is necessary to study their antioxidant properties. The aim of this study was to determine the content of phenolic compounds and the antioxidant potential of ultrasonic extracts of seed and skin of four grape varieties including Hosseini (H), Ghazandaei (G), Ghara Shira (GS) and Rish Baba (RB) cultivated in West Azerbaijan, Iran. Ultrasonic extraction was conducted using acetone, ethanol and methanol. Four methods including DPPH, ABTS, reducing power and total phenolic assays were used to examine the antioxidant potential of the samples. Acetone extracts showed the strongest antioxidant capacity and also had the highest total phenolic content. The antioxidant properties of the seed of grapes were higher than those of their skin. GS grape seed and RB grape skin showed the highest antioxidant activity (P<0.05). Moreover, RB extract had the highest total phenolic content. It was concluded that acetone was the best solvent for extracting antioxidants from grape seed and skin. GS seed and RB skin can be considered as good sources of natural antioxidants.