Antioxidants in Tea

There are four widely accepted methods of measuring the antioxidant potential in beverages:

1. TEAC. Trolox equivalent antioxidant capacity. See Reference #1 below.

2. ORAC. Total Oxygen Radical Absorbance Capacity. See Reference #1 below.

3. DPPH. Free Radical Scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl. See Reference #2-3 below,

4. FRAP. Ferric reducing antioxidant power. See Reference #4 below.


These methods are used to measure the antioxidant capacity in vitro, or out of the living system (eg in a test tube). The use of multiple assay methods is preferred because antioxidant molecules have their own affinity (preferential interactions) with the predetermined reactive species dictated by each assay.

While many marketing departments may tout the total antioxidant benefits of a particular commercial beverage, it is the inherent set of active antioxidants - both their overall free radical scavenging properties and their ability to remain in sufficient quantities over time throughout the organism that may ultimately dictate its benefit over an extended period of consumption. In tea, EGCG appears to undergo a form of polymerization which may also influence its stability and activity.


References

1. Seeram,N.P.;Henning,S.M.;Lee,R.;Niu,Y.;Scheuller,H.S.; Heber,D.Catechin and caffeine contents of green tea dietary supplements and correlation with antioxidant activity. J.Agric.FoodChem. 2006, 54,1599–1603.

2. Malterud,K.E.;Farbrot,T.L.;Huse,A.E.;Sund,R.B. Antioxidant and radical scavenging effects of anthraquinones and anthrones. Pharmacology 1993, 47,77–85.

3.Nenseter,M.S.;Halvorsen,B.;Rosvold,Q.;Rustan,A.C; Drevon,C.A.Paracetamol inhibits copper ion-induced,azo compound initiated, and mononuclear cells-mediated-oxidative modification of LDL. Arterioscler.Thromb.Vasc.Biol. 1995, 15, 1338–1344.

4. Huang,D.;Ou,B.;Prior,R.L.The chemistry behind antioxidant capacity assays. J.Agric.FoodChem. 2005, 53,1841–1856.