What is the unsaponifiable fraction of olive oil?

The unsaponifiable fraction is the part of Virgin olive oils which is not formed by fatty compounds. It only represents 2% of the weight of the oil, but it contains some of the substances that add to the olive oil many of its main features, such as its colour, its aroma and flavor; apart from other benefits to health with antioxidant and anti-inflammatory capacity.

Most of these substances are removed during the refining process, due to they are only found in the Virgin Olive Oils composition or, in lower concentrations, in oils which are a mixture of refined and Virgin.

The unsaponifiable fraction is made up of a large number of components, many of which are in very small concentrations, and can be very variants depending on the variety of the olives and the time of harvest. The family of compounds can be found by clicking here.

We are going to focus our explanation below on the main compounds, either for being the main constituent of the fraction or for its contribution to the oil.

Compounds from fatty acids:

They are phospholipids and waxes. They are in small quantities and are responsible for the occasional formations of mucilage and grounds with gummy appearance in the packagings.

Squalene:

This component can reach 40% of the weight of the unsaponifiable fraction. Its name comes from shark, because one of the main sources of squalene is the shark´s liver oil.

It is a substance that the body produces naturally. Squalene is a natural fat from the skin, whose function is to keep it hydrated to preserve its elasticity and flexibility. However, its production decreases progressively with age. For this reason, many body creams and lotions incorporate squalene in its composition.

The main application of this component is in cosmetics, although, given its antioxidant and reducing properties of the "bad" cholesterol (LDL), is beginning to be used in pharmacology and as functional food additive.

Squalene is present, apart from in sharks, in all vegetable oils, being the Virgin olive oil which has higher concentration of squalene. Since squalene demand is on the rise, the cosmetic industry begins to be interested in Virgin olive as a source of squalene oil.

B-carotene:

Β-carotene is the precursor substance of vitamin A. It is a fat-soluble antioxidant and increases the efficiency of the immune system. In the northern countries is administered orally as a protector against UV rays since its intake reduces the incidence of some cancers of the skin.

B-carotene gives to the olive oil its characteristic yellow-orange colour.

Α-tocopherol:

The a-tocopherol or vitamin E is a powerful natural antioxidant agent and a natural protector of fat against oxidation. It is an element which gives great stability to the olive oil.

The concentration of tocopherols varies depending on the time of harvest. In the early crops, when the olive is passing from green to purple (maturation process), the level of concentration is the highest and it decreases progressively as mature.

Polyphenols:

Exclusive components of the virgin olive oils, because they are not in any other vegetable oil (They are present in wines and other vegetal foods). They are responsible of the characteristic bitter taste of the Olive Oils. The most representatives in the olive oils are the hydroxytyrosol and oleuropein.

The most important of polyphenols is that they are the main responsible of the antioxidant properties of olive oil and therefore they are protective substances against diseases caused by oxidative damage (cancer, heart disease, stroke, etc).

Their antioxidant properties, as well as a-tocopherol, give also stability to the saponificable fraction, preventing and delaying the oxidation of triglycerides.

Its concentration in Virgin olive oils is highly changing and depends on many factors, among them the variety of olives used and the time of harvesting. Picual harvested at early date oils tend to have high polyphenol levels.

Recently, the UE has approved a rule that allows to label as heart-healthy product those virgin olive oils with concentrations higher than 250 mg of hydroxytyrosol and its derivatives per kg of olive oil.

Another phenolic component in extra virgin olive oil is the oleocanthal. This compound has anti-inflammatory properties like ibuprofen. It is responsible of the pungent sensation that the olive oils produce in the throat. Currently there are some investigations about the protective function of the oleocanthal and the Alzheimer's disease, although our opinion is that the results are not conclusive yet.

In the same way, there are investigations describing antitumoral properties of the olecanthal in some kinds of tumors. (Scientific Report of the hospital of Santiago de Compostela).

Pigments:

We have already commented that the beta carotene is the substance that gives the olive oil its yellow-orange color. Following we have to comment those which colored in green the olive oils, which are the chlorophylls.

From the presence of the B-carotenoids and chlorophylls, and their relative proportion, are obtained all the colors of the Olive Oils, from greens to the intense golden.

The presence of chlorophylls in the green olives is higher than in the ripe ones, so that olive oils produced with green olives will be of an intense green. When the olives are becoming mature, the levels of chlorophyll decrease and the golden tones of B-carotenes start to appear.

Volatile and aromatic compounds:

This group of compounds is formed by more than 100 different substances such as hydrocarbons, alcohols, aldehydes, terpenes, furans, etc. They are responsible for the aroma of the oil.

Their analysis is very complex because they are present in very small concentrations. Like the polyphenols its concentration decreases with the maturation of the olive. They are the main responsible of the green and fruity attributes of the virgin olive oil. 

To be volatile, if the oil is heated, disappear in the air. This is one of the reasons why some olive oils are extracted in cold, to preserve all the volatiles and keep all the aromas of the olive oil.