Antioxidant activity of barley tea and their composition

In our previous paper, we assessed the antioxidant effect of warm water ext ract from barley grain on the oxidative deterioration of oil. In the presen t, antioxidant compositions in hot water extract from barley grain (referre d to as barley tea hereafter) were identified, and their antioxidant activi ty was measured. Polyphenols in barley tea were identified by using high pe rformance liquid chromatography (column, Develosil ODS-HG, mobile phase, di stilled water-acetonitrile-0.05 M phosphoric acid 90:10:0.05 v/v), thin-lay er chromatography (the fraction by silicagel G 60) and ultra violet spectru m analysis. Antioxidant activity was assessed by the Rancimat method so as to determine the rancid point (induction time) and the oven test. Polypheno ls in barley tea was detected, and the structures of polyphenols were estab lished as catechol, gallic and gentisic acids, gallocatechin (GC) and epiga llocatechin gallate (EGCG). The main component of polyphenols was catechol. On the other hand, very small quantities of the GC and EGCG existed in bar ley tea. Barley tea and ethyl acetate extract obtained from barley tea show ed preventive effects on oxidative deterioration of oil. Especially, ethyl acetate extract were markedly higher than that barley tea. Antioxidant acti vity of gentisic and gallic acids showed a greater preventive effect.