Chemical Composition

  • Free fatty acids
  • Phospholipids
  • Sterols
  • Phenols
  • Tocopherols
  • Pigments
  • Volatile organic compounds
  • Resinoid and gelatinous substances

Fatty acids

The composition of olive oil in fatty acids is not a steady one. It depends on such factors as the olive variety, each olive growing area’s soil and climate conditions, and the olive fruit’s degree of maturity. The element which differentiates olive oil from all other oils is the fact that it mainly contains monounsaturated fatty acids.

As evidence suggests, those fatty acids appear to be more effective in reducing LDL cholesterol, the so-called “bad” cholesterol. The main fatty acids (unsaturated) in olive oil are the following: oleic; linoleic; linolenic; arachidic; and palmitoleic.

The main constituent of olive oil is oleic acid which is found in greater amounts than those of the remaining acids. The main fatty acids (saturated) in olive oil are palmitic acid, which is found in greater amounts than those of the remaining saturated acids, and stearic acid.


Virgin olive oil is poor in phospholipids. Most of the quantity of those phospholipids derives from the olive pit. Lecithin and cephalin are the phospholipids usually found in olive oil.


Sterols are cyclic alcohols of great molecular weight. They are found in all natural fatty material either free forming or, as esters, bonded with fatty acids. They are soluble in fats, in oils, and non-polar solutions. They are insoluble in water.

Depending on their origin they are divided into zoosterols (a characteristic of animal fatty substances), phytosterols (a characteristic of the higher plants’ fatty substances), and mycosterols (encountered in lower plants, especially fungi).


Another category of natural antioxidants encountered in great quantity in olive oil are phenols which derive from olive tree leaves. The main phenols contained in oils are tyrosol, which free forms in all olive oils, and hydroxytyrosol which has exceptionally high antioxidant activity.


Tocopherols are natural antioxidants found in oils. The antioxidant activity of tocopherols increases as we move from their alpha to their delta form. Their antioxidant action aside, tocopherols also show vitamin activity which increases in the opposite direction than that of the antioxidant activity, i.e., it is higher in the delta-Tocopherols and lower in the alpha-Tocopherols. Determining tocopherol concentration in olive oil is useful in detecting potential olive oil adulteration with other oils deriving from plants. The main tocopherols are: alpha-Tocopherol, beta-Tocopherol, gamma-Tocopherol, and delta-Tocopherol.