OK this is the science bit – but a simple “Olive Oil Food chemistry” lesson is always important for all of us.
Extra virgin olive oil is the highest quality of olive oil. It is the juice of the olive fruit, produced solely by mechanical means, without having undergone any chemical or other treatment. It is a unique, traditional, Mediterranean product whose quality is directly related to the cultivation method, the way and the time of harvest, the method of extraction and the way it is finally stored.
What makes it valuable, compared to other vegetable oils, is its unparalleled taste combined with its high nutritional value. The most striking of all, however, is that the aromatic notes and its remarkable bioactive properties come from 1-2% of its unsaponified fraction!!.
Olive oil composition
“Saponified fraction”
Olive oil composition is about 98-99% triglycerides, namely fatty acid compounds (about 20 different ones) with glycerol molecules, responsible for the greasy taste in the mouth, which we designate as saponified fraction.
Olive oil is probably the only fatty substance which has as one of its main structural features, a monounsaturated fatty acid called oleic acid (C18:1).
Oleic acid, C18:1, has the following properties:
• Protects gastric mucus, reduces secretion of hydrochloric acid and the risk of gastric ulcer
• Reduces the secretory activity of pancreas and bile, improves bile discharge through the gallbladder, prevents the formation of stones in the bile, facilitates the absorption of fat-soluble vitamins and calcium,
acting as a laxative during fasting and helps in chronic constipation
• Reduces the creation of bad cholesterol (LDL) and reduces the risk of cardiovascular episodes
• Protects the product from rapid oxidation
The factors which determine the oleic acid concentration in olive oil are the variety of the olive fruit to a significant extent and the climate conditions.
“Unsaponifiable fraction”
The remaining 1-2% of the olive oil composition, concerns the rest of the bioactive ingredients, consisting of more than 200 different compounds, which we designate as unsaponifiable fraction.
Despite their small percentage, these components play an important biological role for the health of the human body and for the product itself. In addition, they are responsible for the main flavor and smelling properties (organoleptic characteristics) that are found in an olive oil.
The main ones being:
• Sterols, predominantly β-sitosterol
Several studies have shown that this particular sterol reduces the concentration of bad cholesterol (LDL). Other sterols are stigmasterol and campesterol.
• Tocopherols, mainly the α-tocopherol (vitamin E)
Tocopherols are fat-soluble vitamins and contribute to the stability of olive oil and to the defense of the human body. Apart from their vitamin effect, they are the most important antioxidants that protect our cellsand tissues from inevitable aging as well as from degenerative diseases and cancer.
• Hydrocarbons, the main component being squalene
Hydrocarbons act as antioxidants and contribute both to the resistance of the oil and the defense of the human body. Research has shown that squalene reduces bad cholesterol (LDL) and protects against cancer.
• Polyphenols or phenols, mainly tyrosol, hydroxy-tyrosol and oleuropain, oleochantal
The various phenolic compounds found in extra virgin olive oil do not exist in other fats, making it a unique product and differentiating it from other inferior quality vegetable oils such as seed oils, sunflower oil andolive-pomace oil which are extracted by chemical and not mechanical means, as well as refined olive oils. The «renowned» phenols determine the flavor of olive oil and depending on their concentration they are responsible for the intensity of its bitter and spicy taste. Consequently, olives with a high content of phenols are strongly bitter and spicy.
Phenols are an integral part of the diet, act as natural antioxidants and protect olive oil from its normal oxidation process while at the same time the health of our body.
Surveys, studies and measurable results for over 30 years on phenols in extra virgin olive oil and their effect in the health of the human body have shown the following significant benefits:
• Antioxidant action
• Anti-inflammatory action
• Protection of the cardiovascular system
• Positive effect on the immune system
• Positive effect on the central nervous system
• Action against cancer
With regard to the protection of the cardiovascular system, there is the European regulation 432/2012 (Commission Regulation (EU) No 432/2012 of 16 May 2012), of the European Food Safety Authority (EFSA), which states: «Olive oil polyphenols contribute to the protection of the blood lipids from oxidative stress». According to the health claim, a daily consumption of at least 5 mg (about 2 tablespoons) of hydroxytyrosol and its derivatives is recommended in order to have a positive effect on cardiovascular diseases by reducing the peroxidation of blood lipids.
As most of the phenolic compounds found in olive oil are located in the flesh of the fruit, the phenolic composition in an olive oil is largely determined by:
• the genetic characteristics of each variety (it has been proven that there are varieties which produce a higher amount of phenols, such as Koroneiki variety)
• the ripening degree of the fruit at harvest (the more mature you collect the fruit the less concentration in phenols)
• the climate and soil conditions
• the olive oil extraction process, especially during the crushing of the fruit and the malaxation which follows (the temperature is key in both stages as well as the duration of the malaxation)
In conclusion, the phenolic components of an olive oil are the result of enzymatic processes that are activated through the mechanical production process (during crushing and malaxation).
• Pigments, which determine the color of an olive oil
In particular, chlorophyll gives a bright green color, carotenoids give a yellow color and finally pheophytin which is a derivative of chlorophyll gives a dark green color. All olive oils contain carotenoid pigments and are therefore based on the yellow color.
• Volatile compounds, all the pleasant or unpleasant odors that we perceive either with the nose or with the mouth
In an extra virgin olive oil there are various volatile compounds that characterize its aroma.
The most important enzymatic process that produces the positive aromas in an extra virgin olive oil is that of lipoxygenase. It is a biochemical process that is activated during the crushing process of the fruit (only by mechanical means in the crusher).
The crushing of the fruit is catalytic since during this process, in a few seconds only, are generated about 70% of volatile compounds that characterize the aroma of an olive oil.
