During extraction of olive oil, highly polar polyphenols are retained in the olive pulp, or alpeorujo, which is used as the raw material for olive powder.

The principle polyphenols in olives are tyrosol and hydroxytyrosol, which are both derivatives of the antioxidant oleuropein. These phenolic olive compounds have some of the highest antioxidant activity of any similar compound found in nature.
Polyphenols, tocopherols and other natural antioxidants found in olives are known to prevent lipid oxidation and formation of free radicals in the body, which contribute to tissue damage.

The ability of antioxidants in food to neutralise free radicals can be measured and expressed by the oxygen radical absorbance capacity (ORAC). Studies have demonstrated that there is a strong correlation between antioxidants in food and ORAC values. Flavonoids are one of the many naturally occurring components which contribute to the antioxidant activity of foods.