Olive oil is the only fat obtained from the fruits of the olive tree by mechanical extraction. Othervegetable fats like seed oil are produced by solvent extraction. Cold pressing does not alter the chemical composition of the drupes so all their natural elements - including vitamin E, beta-carotene, chlorophyll, phenolic compounds, etc. – are transferred to the final products as ‘minor’ components. Even if they are present in small amounts, they do contribute organoleptic, merceological and nutritional features to the quality of the final product.
From a chemical point of view, olive oil is composed of 98-99.5% triglycerides (the saponifiable fraction), which are glycerol esters of fatty acids. Fatty acids are made up of monounsaturated fatty acids (75%, mostly oleic acid), saturated fatty acids (16%, mostly palmitic acid), and polyunsaturated fatty acids (9%, with a higher content in linoleic acid than in linolenic acid). From a merceological standpoint, the high level of oleic acid confers olive oil greater stability as against all other vegetable oils, which have a high content in polyunsaturated fatty acids. The exclusive fatty acid composition and the presence of antioxidants make extra virgin olive oil a very good raw salad dressing, which can also be used for cooking at high temperatures. From a physiological and nutritional point of view, oleic acid stimulates bile secretion, which is paired with increased digestibility and protection of the gastric mucosa. Moreover, oleic acid has been shown to lower blood cholesterol and LDL (‘bad’) cholesterol concentrations, which are responsible for occurrence and progression of atherosclerosis.
Minor components making up the ‘non-saponifiable’ fraction account for 0.5-2% and include hydrocarbons (squalene), tocopherols (vitamin E), sterols (beta-sitosterol), terpene alcohols, pigments (chlorophyll and carotene), carotenoids (beta-carotene and lutein), phenolic (hydroxytyrosol, tyrosol and oleuropein that have an antioxidant effect) and aromatic compounds.Some of those minor components are indeed critical also from an analytical viewpoint since they can serve as markers for evaluating the oil genuineness.
As antioxidants, they are also responsible for the oil shelf life throughout the production process, from extraction to storage, until it comes to our table.
It has been shown that the extra virgin olive oil minor components protect the body’s most important macromolecules (carbohydrates, lipids, proteins and nucleic acids) from oxidation. Hence, they are useful to prevent chronic degenerative diseases (cardiovascular diseases, cancer, degenerative nerve conditions, ageing).
It has to be borne in mind that in oils designated as “OLIVE OIL” (that is not labelled as “EXTRA VIRGIN”) and in seed oils minor components are present in tiny amounts or even absent, as a result of the chemical process they go through.