What is ORAC Total?

Oxygen Radical Absorbance Capacity is a value or score which measures the level of antioxidants in food materials. This is a standardized test adopted by the U.S. Department of Agriculture and it is believed that foods ranking higher on the ORAC scale will more effectively neutralize free radicals and play a role in free radical theory of aging.

How are antioxidants measured through ORAC Total?

ORAC was developed by Dr. Guohua Cao, a physician and chemist at the National Institute on Aging in Baltimore, Maryland. The ORAC total test measures both the time required for an antioxidant to react as well as the quantity of an antioxidant in a given sample. The test also measures how many free radicals a specific food can absorb. Free radicals or reactive oxygen species (ROS) are generated by normal cellular processes, stresses, or ultraviolet radiation. They react and damage cells, tissues, carbohydrates, proteins and lipids. Thus, excess production of free radicals can cause inflammation, premature aging disorders and several diseases like cancer and diabetes. The role of antioxidants then is to protect the fluorescent molecule from oxidative degeneration. A higher rating on the ORAC test means that a particular food product is neutralizing free radicals at a higher rate.

The ORAC test then is used to determine which food product is more efficient as an antioxidant agent. This test is conducted in a test tube. This method is the most acceptable and accurate indicator in determining antioxidant status because it bases its measurements on the amount of fluorescence in the product. It increases the sensitivity and permits a lower molar ratio of antioxidant sample. Thus, this test minimizes the likelihood of cross-reactions between sample and reagents.

The ORAC test is based on the oxidation of fluorescein by peroxyl radicals for both water-soluble and lipid-soluble substances. The antioxidants block the peroxyl radical mediated oxidation of fluorescein until all the antioxidant activity in the sample is finished and, after that, AAPH (2, 2’-azobis-2-methyl-propanimidamide) generates peroxyl radicals which react with and reduce the fluorescence of fluorescein.  It measures the loss of fluorescein by fluorescence over time due to peroxyl-radical formation by the breakdown of AAPH. The area under fluorescence decay curve (AUC) is used to measure the total peroxyl radical antioxidant activity in a sample. The ORAC also measures ‘total radical scavenging ability’

The ORAC-hydro test reflects water-soluble antioxidant capacity, while the ORAC-lipo test measures lipid-soluble antioxidant capacity. The values of these two tests are additive.

Nowadays, it is compulsory to present the ORAC score of an antioxidant drink or dietary food product.  It is recommended that humans eat foods containing at least 3,000 ORAC units a day. The ORAC score of Acai Berry is 18,500, Pomegranate is 3,307 and Noni Fruit Juice (pure) is 1,506.