David Nevue Free Notes

The vine, precious compounds of extra virgin olive

During machining operations (especially during crushing and kneading), extra virgin olive oil is enriched with precious compounds present in low percentages, but extremely important to the quality and stability of the product.

phenolic compounds

From complex glycosides present in the fruit (oleuropein and ligstroside) following the action of hydrolytic enzymes (β-glucosidase) are generated soluble compounds (aglycones)

L ' oleuropein is primarily responsible for bitter taste of the fruits and leaves of the olive, while the aglycones are primarily responsible for the feelings of bitterness and spicy oil. The gradual softening that occurs during storage, especially of oil is not filtered, is due to their subsequent hydrolysis with release of phenol as simple tyrosol and hydroxytyrosol

The antioxidant activity of the aglycones, and in particular those containing hydroxytyrosol (ortho-diphenols), is due to the ability to stop the spread of radical reaction in the autoxidation, yielding a proton, forming a radical stabilized resonance.

Pigments

The formation of the color of an olive oil contribute a large number of fat-soluble pigments such as xanthophylls, chlorophylls, carotenes and carotenoids.

The chlorophyll content in , mainly responsible for the green oil, depends on the system of pressing, the process temperatures and extraction technology (usually by centrifugation for greater pressure) as well as the variety and the degree of fruit ripening (higher in green olives).

These compounds can act as a pro-oxidant agents, in particular in the process of photo-oxidation of oils stored to light.

I carotenoids are mainly responsible for the yellow color of the oil obtained from ripe olives, where the presence of chlorophyll is very small. The compound is mainly present β-carotene, the precursor of Vitamin A.
Hydrocarbons

oil are present in both saturated, straight chain and branched hydrocarbons that unsaturated and polyunsaturated.

Among the unsaturated hydrocarbons is the most abundant oil squalene (400 mg/100 g of oil), triterpene of formula C30H48
Phospholipids

are esters of fatty acids in position 1 and 2 with phosphoric acid at position 3. The latter in turn is linked to low molecular weight amine bases.

are essential components of cell membranes and lipoprotein complexes involved in the absorption and transport of lipids.

They also have an important synergistic action in respect of antioxidants naturally present in virgin olive oil.

present in limited quantities, are represented by phosphatidylcholine and fosfatidilietanolamina .

Filtration dramatically reduces the quantity of oil, refining them away.
Tocopherols

tocopherols are among the most popular natural antioxidants and are found mainly in vegetable oils, where they carry out their action as a mixture of α-β-γ and δ-tocopherol.

In the human, the tocopherols, which must be lipoveicolati to be absorbed, act mainly as inhibitors of intracellular oxidation processes.

The form preferentially absorbed by the human body 's α-tocopherol, or pro-vitamin E, is by far the most abundant in olive oil. The content of tocopherols is strongly influenced by the variety and ripeness of the olives.
Volatile

Through gas chromatographic analysis were identified approximately 200 volatile compounds ofPalestine alcohols, aldehydes, ketones, acids, hydrocarbons.

The gas chromatographic analysis of volatile compounds, however, can not replace the sensory analysis in the perception of the individual compounds by man not is proportional to their concentration, but depends on the threshold of perception that is different for each substance.

addition, the analysis of individual compounds of a particular aroma can hardly express the synthesis that takes into account the interaction between the different odorant molecules.

Sterols

The sterol component of a vegetable oil is very important for the acknowledgment of the identity of that oil which is tightly linked to the botanical family of the seed or fruit from which is extracted oil.

the 94-97% in olive oil is the sterol β-sitosterol

alkyl esters

analysis of ethyl esters of fatty acids is important to determine the quality of oil, if the quantity is high, there was a big fermentation of olives, with poor quality oil derived from these.

The limit is set on the alkyl esters in 75 mg / kg.