Background – Antioxidants are compounds that help prevent oxidation. Information on their presence in foods and their uses as neutralizers of oxidants or free radical compounds in the prevention of chronic non-communicable diseases has attracted scientists in various fields. Hence information related to their analytical determination is crucial.
Objectives – To discuss the major analytical methods in the determination of antioxidants in foods.
Discussion – The choice of analytical methods in the determination of antioxidants depends on the types of antioxidants of interest. Antioxidants in foods could be analysed either as a functional group, antioxidant groups or as individual antioxidants. Functional group could be measured by the total antioxidant capacity (TAC) in the use of any of the following major assays; trolox equivalent antioxidant capacity (TEAC) decolourization (1), ferric reducing antioxidant power (FRAP) (2) and oxygen radical absorbance capacity (ORAC) (3). The major antioxidant group assays include the determination of total polyphenol (TPP) performed by the Folin-Ciocalteu method, total carotenoids, total anthocyanins and total flavonoids (4). The determinations of individual antioxidants such as carotenoid and flavonoid profiles include the use of HPLC and LC-MS and other complex assays (5).
Conclusion – Attempts are made to validate the antioxidant assays in the Pacific region for use as a routine analysis in regional laboratories.
References
1 Re R, Pellegrini N, Proteggente A, Pannala A, Yang M and Rice-Evans C. Antioxidant activity applying an improved abts radical cation decolorization assay. Free Radic. Biol. Med, 1999; 26, 1231-1237.
2 Pulido R, Bravo L and Saura-Calixto F. Antioxidant activity of dietary polyphenols as determined by a modified ferric reducing/antioxidant power assay. J. Agric. Food Chem, 2000; 48, 3396-3402.
3 Cao G and Prior RL. Measurements of oxygen radical absorbance capacity in biological samples. In Methods in Enzymology: Oxygen radicals in biological systems. New York, Academic press, pp. 51-62.
4 Sellappan S, Akoh CC. Flavonoids and antioxidant capacity of Georgia-grown Vidalia onions. J. of Agric. and Food Chemistry, 2002a; 50: 5338-5342.
5 Lako J, Trennery VC, Wahlqvist M, Wattanapenpaibbon T, Sotheeswaran S, and Premier R. Phytochemical flavonols, carotenoids and the antioxidant properties of a wide selection of Fijian fruit, vegetables and other readily available foods. Food Chemistry 2006; in press.