Oleic acid is a monounsaturated fatty acid belonging to the omega-9 family of fatty acids.
It is naturally found in vegetable oils such as olive oil, avocado oil, safflower oil, and canola oil.
Olive oil contains between 61% and 83% oleic acid, depending on the olive variety and growing conditions. The oleic acid content does not depend on the quality of the oil, the extraction method (mechanical or using chemical solvents), or whether the olive oil has been refined.
Characteristics of oleic acid
One of the main characteristics of oleic acid is that it is the most stable unsaturated fatty acid:
- It is more resistant to oxidation than polyunsaturated fatty acids (omega-6 and omega-3).
- It is more stable at high temperatures than polyunsaturated fatty acids (omega-6 and omega-3). For this reason, olive oil is more stable than sunflower oil for frying, since sunflower oil is mainly composed of linoleic acid (omega-6).
Health benefits of oleic acid
Many of the health benefits of olive oil come directly from oleic acid. Its primary benefit is its protective effect on the cardiovascular system. It helps lower blood pressure, reduces LDL ("bad") cholesterol, and increases HDL ("good") cholesterol.
Physical properties of oleic acid
In its pure form, oleic acid is a colorless and odorless liquid.
Its melting point is 15 ºC. Therefore, olive oil begins to solidify when the temperature falls below this point.
Its boiling point is 360 ºC. However, for cooking, the smoke point is more important because it determines the maximum temperature at which an oil can be used before it starts to break down. Olive oil, which is composed mainly of oleic acid, has a smoke point below 220 ºC.
Chemical formula of oleic acid
The molecular formula of oleic acid is C18H34O2.
Like all fatty acids, the oleic acid molecule has a carbon chain structure with a carboxyl functional group (COOH) at one end.
Within the carbon chain, there is a double bond between carbon atoms 9 and 10 (counting from the carboxyl group), giving oleic acid its monounsaturated structure. It belongs to the omega-9 family of fatty acids, and many of its health benefits are attributed to this chemical characteristic.
Amount of oleic acid in olive oil
Most olive oil consists of oleic acid. However, its concentration varies depending on the olive variety used to produce the oil. Some varieties naturally contain a higher percentage of oleic acid than others. The table below shows the approximate oleic acid content of several olive varieties.
| Olive variety | % oleic acid |
| Picual | 76 |
| Cornicabra | 77 |
| Hojiblanca | 74 |
| Frantoio | 67 |
| Manzanilla | 72 |
| Arbequina | 65 |
Amount of oleic acid in other vegetable oils
Each vegetable oil contains a different proportion of fatty acids. This fatty acid portion is known as the saponifiable fraction.
Other foods rich in oleic acid
In addition to vegetable oils, which contain varying amounts of oleic acid, another important source is nuts, including almonds, peanuts, hazelnuts, pistachios, and walnuts.
Oleic acid is also found, although in smaller amounts, in certain types of meat, such as pork.
What is high oleic sunflower oil?
High oleic sunflower oil is sunflower oil from sunflower plants that have been genetically modified to produce more oleic acid. It is widely used in the food service industry.