Combined use of multiple methodologies for the measurement of total antioxidant capacity in UK commercially available vegetable juices.

Substantial evidence exists to support the hypothesis that high fruit and vegetable consumption, rich in antioxidants, can reduce the incidence of several disease states. The aim of this study was to compare the results obtained by six spectrophotometric biochemical methods including the ferric reducing antioxidant power (FRAP), 2, 2-diphenyl-1-picryhydrazyl (DPPH•), 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS•⁺), copper (II) reducing capacity (CUPRAC) and Cerium (IV) reducing antioxidant capacity (CERAC) assays as well as Folin-Ciocalteu method (FC) for the measurement of total antioxidant capacity (TAC) and total polyphenols (TP) in different commercially available vegetable juices. There was a significant positive correlation between the results obtained for FRAP, ABTS•⁺, CUPRAC, CERAC and FC (0.68 ≤ r ≤ 0.96, P < 0.01). DPPH• was only correlated with CERAC (r = 0.66, P < 0.01). Beetroot juice had the highest TAC and TP regardless of the method of analysis.