Olive oil

Olive oil is mainly a mixture of esters and glycerol (triglycerides), and higher fatty acids, some of which are unsaturated although others are saturated. Besides triglycerides, olive oil contains small amounts of other ingredients such as: free fatty acids, phosphatides (lecithins), sterols, phenols, tocopherols, pigments and various retinoids and gelatinous substances (Kirizakis, 1988).

Triglycerides make up about 98.5-99.5% of the components in olive oil, and are what we call the saponifiable fraction, while the remaining 0.5-1.5%, which is the unsaponifiable fraction of the olive oil, is responsible for its main flavours and aromas.

The composition of fatty acids in olive oil, as with other vegetable oils, depends on the variety, the climatic conditions of the area where the trees are grown and various other factors.

Most of the fatty acids in olive oil are unsaturated acids. Among these, monounsaturated oleate (18: 1) is to be found in the largest quantities. The second most abundant unsaturated fatty acid found in olive oil is linoleic (18: 2). The other unsaturated acids, (linolenic (18: 3), arachidonate (20: 4) and palmitoleate (16: 1)) are present in olive oil in very small amounts. Of the saturated acids, palmitate (16: 0) is found in the highest concentrations, followed by stearic acid (18: 0). The main glycerides in olive oil are those of oleic acid, which on their own make up 70-80% of the weight of the oil. Because these glycerides are liquid at room temperature, olive oil as a whole remains liquid at normal room temperatures (Kirizakis, 1988).

Range of percentages in the fat content of olive oil.

International Olive Oil Council (1984)

Olive oil provides an exceptionally large number of benefits to the human body because:

•  of its good balance between saturated and monounsaturated fatty acids.
• of its good balance of Vitamin E and polyunsaturated fatty acids (mainly linoleic).
• linoleic acid makes up about 10% of the oil’s fat content, which matches the human body’s needs in essential fatty acids.
• natural antioxidants are present in olive oil : It contains a wide variety of vitamins and antioxidants, including the most active biological form of vitamin E (α-tocopherol), carotenoids and antioxidant phenols such as oleuropein.
• it contains squalene, which is both a precursor for sterols and an antioxidant and which plays a major role in metabolism, in higher quantities than any other fatty substances.
• it has an excellent linoleic to α-linolenic acid ratio, which is similar to the ratio found in the fat in human milk. The fat composition of olive oil is similar to breast milk. In fact, the only fat which is digested in a greater proportion than the fat in olive oil, is that in breastmilk (Gyorgy 1969).
• due to its low polyunsaturated fat content and its strong antioxidant properties, olive oil is particularly resistant to oxidation. This property is unique to olive oil.
• olive oil does not contain Trans-unsaturated fatty acids, cholesterol or salts

A bitter taste is good for your health. Why does olive oil have a bitter taste?

The phenols and oleuropein contained in olive oil are responsible for its bitter taste and the way it gives you a slight burning sensation on your throat. The main ingredients contained in the unsaponifiable part of olive oil are: Hydrocarbons, Sterols, Tocopherols, Carotenoid pigments, Terpene alcohols, Phenols, Phospholipids, Pigments, Volatile Ingredients and Oleuropein.

These ingredients are responsible for the main flavours and scents of olive oil. Phenols are an important class of natural antioxidants which are found in olive oil in significant amounts. The main phenols present in olive oil are tyrosol, hydroxy-tyrosol and phenolic acids, such as Caffeic acid and Protocatechuic acid. The existence of these phenols greatly enhances olive oil’s resistance to oxidation. These natural antioxidants give the oil its bitter taste and the slight burning sensation you feel in your throat when tasting it. Eliperoin is another phenolic compound which is present in olive oil and which gives it its characteristic bitter taste. The quantity of Eliperoin varies depending on the type of olive, the climate and the method of harvesting used.

When olive oil is stored, the oleuropein content decreases due to enzymatic hydrolysis and the olive oil loses its fruity and bitter taste. Oleuropein has a similar effect to phenols with its antioxidant action. Furthermore, Oleuropein is also responsible for olive oil’s anti-hypertensive, anti-inflammatory, antibiotic and digestive actions.