Determining ORAC
Unraveling the science of food is a multidisciplinary effort involving a diverse range of chemists, life sciences experts, and physicians. As a result, many of the milestones in food and nutrition have been an outcome of combined biological (in vivo) and analytical (in vitro) assays. As the potential therapeutic value of antioxidants becomes further elucidated, a sophisticated approach to determine the efficacy of these substances is being developed.
Antioxidants help break down or "quench" the cell-damaging compounds known as free radicals that are thought to contribute to cancer, cardiovascular disease and cognitive decline. Progress in determining the link between the dietary content and physiological benefit are reliant on an effective measurement of biological potential. The Oxygen Radical Absorbance Capacity (ORAC) test is an in vitro or in vivo assay designed to measure the total antioxidant power of foods and other chemical substances by tracking chemical biomarkers. The assay represents a breakthrough in antioxidant testing because it measures both lipophilic and hydrophillic extracts and is the first tool for measurement of total antioxidant capacity.
The assay combines a sample with a chemical marker that fluoresces and an oxidizing agent. Although other methods had been developed to measure antioxidant potential, the ORAC assay has the most relevance to biology since it utilizes a peroxyl radical generator in the assay. The peroxyl radical is not only one of the most common reactive oxygen species but is also reactive with both water and lipid soluble substances. Trolox is a widely accepted standard for antioxidant activity and ORAC results are expressed as micromole (µM) Trolox equivalents (TE) per gram with one ORAC unit being equivalent to the net protection area provided by 1µM of Trolox.
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Richard Crowley Food Product Design
December 2004 Download PDF
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