Virgin olive oil has a unique chemical composition compared to other vegetable oils.
One of the reasons for this unique composition is that most vegetable oils are extracted from seeds using solvents, which remove only the fat. In contrast, virgin olive oil is extracted directly from olives by mechanical means, as the oil is naturally contained in the flesh of the fruit. As a result, many compounds naturally associated with the oil in the olive are retained in virgin olive oil.
Another reason is that olives contain unique compounds that are not found in other vegetable oils. These compounds play an important role in both the health benefits and the organoleptic characteristics of virgin olive oil.
Finally, the fatty acid profile of olive oil, characterized by its high content of oleic acid, also makes it unique among vegetable oils.
The chemical composition of virgin olive oil can be divided into two main fractions:
A) Saponifiable Fraction (98–99%)
A.1 Triglycerides (96%)
A.2 Diglycerides (2%)
A.3 Free Fatty Acids (0.5%)
B) Unsaponifiable Fraction (1–2%)
B.1 Compounds Derived from Fatty Acids:
B.1.1 Phospholipids (40–135 mg/kg)
B.1.2 Waxes (approximately 250 mg/kg)
B.1.3 Sterol Esters
B.2 Non-Fatty Acid Compounds:
B.2.1 Hydrocarbons
B.2.1.1 Squalene (8,000 mg/kg)
B.2.1.2 β-carotene, a precursor of vitamin A (4 mg/kg)
B.2.2 Fatty Alcohols (1,500–2,000 mg/kg)
B.2.3 Sterols (1,000–2,000 mg/kg)
B.2.4 Tocopherols (Vitamin E) (50–300 mg/kg)
B.2.5 Pigments (40 mg/kg)
B.2.6 Polyphenols (50–800 mg/kg)
B.2.7 Volatile and Aromatic Compounds
Comments on the Chemical Composition of Extra Virgin Olive Oil
a) Olive oil consists mainly of the saponifiable fraction, which is essentially fat. Like other vegetable oils, most of this fat is made up of triglycerides, the form in which plants naturally store fats. Diglycerides and free fatty acids are either intermediate compounds formed during triglyceride synthesis or the result of triglyceride breakdown.
b) The unsaponifiable fraction represents only a small proportion of virgin olive oil, yet it contains a wide variety of compounds present in small quantities. These substances are responsible for many of the oil's most important characteristics, including its color, flavor, and aroma, as well as its antioxidant and anti-inflammatory properties, which contribute to its health benefits.
c) The concentration of compounds in the unsaponifiable fraction can vary considerably, as it depends on many factors, including the olive variety, growing conditions, and extraction process.
d) Most of the compounds in the unsaponifiable fraction are lost during the refining process.