Why the ORAC assay is advantageous over many other methods?
The mechanism of ORAC is based upon the sound chemical principle and the uniqueness of ORAC lies in the AUC quantitation technique. Indeed, many other methods have been developed for antioxidant activity, such as TEAC (Trolox Equivalent Antioxidant Capacity)1, TOSC (Total Oxyradical Scavenging Capacity)2, FRAP (Ferric Reducing Antioxidant Power)3, and DPPH method4. However, the fatal drawback of these methods is either no oxygen radical involved or lack of complete quantitation technique.  Therefore, only ORAC provides antioxidant activity mechanistically and physiologically.

1 Re, R.; Pellegrini, N.; Proteggente, A.; Pannala, A.; Yang, M.; Rice-Evans, C. Antioxidant activity applying an improved ABTS radical cation decolorization assay. Free Radic. Biol. Med. 1999, 26, 1231-1237.

2 Winston, G. W.; Regoli, F.; Dugas, A. J.; Fong, J. H.; Blanchard, K. A. A rapid gas chromatographic assay for determining oxyradical scavenging capacity of antioxidants and biological fluids. Free Radic. Biol. Med. 1998, 24, 480-493.

3 Benzie, I. F. F.; Strain, J. J. The ferric reducing ability of plasma (FRAP) as a measure of ''antioxidant power'': The FRAP assay. Anal. Biochem. 1996, 239, 70-76.

4 Hirano R., Sasamoto W., Matsumoto A. Antioxidant ability of various flavonoids against DPPH radicals and LDL oxidation. J NUTR SCI VITAMINOL. 2001, 47, 357-362.