Validation of a quantitative assay for the total content of lipophilic and hydrophilic antioxidants in foods

Bente L Halvorsen; Rune Blomhoff

doi:10.1016/j.foodchem.2010.12.142

Validation of a quantitative assay for the total content of lipophilic and hydrophilic antioxidants in foods

Food Chem. 2011 Jul 15;127(2):761-8. doi: 10.1016/j.foodchem.2010.12.142. Epub 2011 Jan 9.

Authors

Bente L Halvorsen¹, Rune Blomhoff

Affiliation

¹ Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1046 Blindern, 0316 Oslo, Norway.

PMID: 23140732
DOI: 10.1016/j.foodchem.2010.12.142

Abstract

One of the main methods used to assess total antioxidant content in foods is the Ferric Reducing Ability of Plasma (FRAP) assay. The FRAP assay has previously not been extensively validated. In the present study, 39 pure compounds, such as different polyphenols, ascorbic acid, tocopherols, tocotrienols and carotenoids dissolved in water/methanol, water/2-propanol and 2-propanol, were tested. Our results demonstrate that the FRAP assay can quantitate satisfactorily most hydrophilic and lipophilic compounds with antioxidant properties. The reaction was followed for 60min. The most extensive reaction occurred within the first 4min for most compounds and foods. The lipophilic tocopherols and tocotrienols were easily quantitated and reached endpoint within 4min while carotenoids were somewhat more demanding due to low solubility and slower reaction kinetics. We conclude that the FRAP assay, with 4min reaction time, is suitable for high-throughput screening of total antioxidant content of edible items.