Total Antioxidant Capacity of Teas by the Ferric Reducing/Antioxidant Power Assay

Abstract

This study aimed to compare in vitro antioxidant power of different types of tea (Camellia sinensis). The ferric reducing/antioxidant power (FRAP) assay was used to measure the total antioxidant power of freshly prepared infusions of 25 types of teas. Results showed that different teas had widely different in vitro antioxidant power and that the antioxidant capacity was strongly correlated (r = 0. 956) with the total phenolics content of the tea. Expressed as micromol of antioxidant power/g of dried tea leaves, values ranged as 132-654 micromol/g for black ("fermented") teas, 233-532 micromol/g for Oolong ("semifermented") teas, and 272-1144 micromol/g for green ("nonfermented") teas. One cup of tea of usual strength (1-2%), therefore, can provide the same potential for improving antioxidant status as around 150 mg of pure ascorbic acid (vitamin C).

Phenolic compounds and antioxidant activity of rice

“…Cells are continuously exposed to oxidants from endogenous and exogenous sources and the production of free radicals is a part of the metabolism. The organism also has antioxidant compounds from endogenous and exogenous sources participating in the maintenance of the balance between oxidants and antioxidants (Benzie and Szeto, 1999;Fogliano et al, 1999;Heim et al, 2002). The disequilibrium in this balance due to the alteration in the concentration of these compounds is called oxidative stress, which results in damage to the cells and tissues in several ways: damaging the biomolecules and cell components, activating specific signalling paths, originating toxic products, changing gene expression and enzyme activity, and interrupting normal mechanisms of cell repair.…”

The effect of method, standard and sample components on the total antioxidant capacity of commercial waters assessed by optical conventional assays

“…FRAP assay measures the ability of antioxidants to reduce the ferric 2,4,6-tripyridyl-s-triazine complex [Fe(III)-(TPTZ)2] 3+ to the intensely blue coloured ferrous complex [Fe(II)-(TPTZ)2] 2+ , in acidic medium, with an absorption maximum at 593 nm (Benzie & Strain, 1999;Benzie & Szeto, 1999;Griffin & Bhagooli, 2004;Prior et al, 2005;Pulido et al, 2000;Sánchez-Alonso et al, 2007). FRAP reaction detects compounds with redox potentials <0.7 V (redox potential of Fe 3+ -TPTZ).…”

“…Ferric reducing antioxidant potential (FRAP) (Benzie & Strain, 1999;Benzie & Szeto, 1999;Griffin & Bhagooli, 2004;Prior, Wu, & Schaich, 2005;--Pulido, Bravo, & Saura-Calixto, 2000;Sánchez-Alonso, Jiménez-Escrig, Saura-Calixto, & Borderías, 2007), trolox equivalent antioxidant capacity (TEAC) (Castro, Rogero, Junqueira, & Carrapeiro, 2006;Pellegrini et al, 2003), oxygen radical absorption capacity (ORAC) (Cao et al, 1993;Ou, Hampsch-Woodill, & Prior, 2001;Ou, Huang, Hampsch-Woodill, Flanagan, & Deemer, 2002;Prior et al, 2005) and total reactive antioxidant potential (TRAP) (Ghiselli, Serafinni, Natella, & Scaccini, 2000;Prior et al, 2005;Sánchez-Moreno, 2002) are examples of methods used to determine TAC. Mechanistically, these methods are based either on single electron transfer or hydrogen atom transfer reactions between an oxidant and a free radical (Sánchez-Moreno, 2002).…”

Process optimization for osmo-dehydrated carambola (Averrhoa carambola L) slices and its storage studies

“…The total antioxidant potential in terms ferric reducing antioxidant power (FRAP) was carried out by using methanolic extracts of the osmo-dehydrated products (Benzie and Szento 1999).…”