The additive properties of Oxygen Radical Absorbance Capacity (ORAC) assay: The case of essential oils.

The ORAC assay is applied to measure the antioxidant capacity of foods or dietary supplements. Sometimes,
the manufacturers claim antioxidant capacities that may not correspond to the constituents of
the product. These statements are sheltered by the general understanding that antioxidants might exhibit
synergistic properties, but this is not necessarily true when dealing with ORAC assay values.
This contribution applies the ORAC assay to measure the antioxidant capacity of ten essential oils typically
added to foodstuffs: citronella, dill, basil, red thyme, thyme, rosemary, oregano, clove and cinnamon.
The major components of these essential oils were twenty-one chemicals in total. After a
preliminary discrimination, the antioxidant capacity of eugenol, carvacrol, thymol, a-pinene, limonene
and linalool was determined. The results showed that 72–115% of the antioxidant capacity of the essential
oils corresponded to the addition of the antioxidant capacity of their constituents. Thus, the ORAC
assay showed additive properties.