The quality of oil is determined by the evaluation of a set of characteristics: colour, aspect, subtlety, richness, balance and character. By tasting it, you can identify some very important chemical components without any laboratory analysis.
Polyphenols organoleptic flavour is bitter and spicy: the more polyphenols there are, the bitter the oil is. Polyphenols are good for health: they are antioxidant substances that act both on oil, avoiding oxidation and rancidity, and on the human body cells. They are numerous in fresh oils, which in fact lose hotness (and therefore polyphenols) as time goes by.
Identifiable by the oil intense green colour. Together with polyphenols, they help to give antioxidant and protective virtues to the food.Chlorophylls tend to degrade with light, which is why it is recommended to keep oil in dark packages in dark places. An oil exposed to light may turn yellow because it loses chlorophyll; when this change takes place we say the oil is oxidised.
Along with the chlorophylls, carotenoids are the pigments responsible for the oil colouring: carotenoids give yellow and orange reflexes. As the other two elements discernible through tasting, carotenoids too are antioxidant substances.
The smell and taste sensations come together in the final judgment, which describes and defines the extra virgin olive oil. For this, they use the universal terms that describe the characteristics and defects as directed by Reg. (EC) n.2568 / 91.
Winey: unpleasant flavour caused by the prolonged storage of the olives after harvest, which appears as a result of the formation of acetic acid. It is clearly recognisable by the strong vinegary flavour.
Fiscolo: unpleasant flavour, rancid, typical of oils obtained from the pressing of the olive paste by the extraction system with dirty presses using dirty and full of fermented residues baskets
Leaf: bitter flavours typical of oils obtained from pressed olives with leaves and olive twigs.
Musty: flavour typical of a badly stored oil, remained too long in contact with its lees.
Mold: unpleasant flavour created by olives stored for several days in humid conditions.
Rancid: unpleasant flavour due to a prolonged contact with the air and extended ageing.
Reheating: the shortcomings of oils obtained from olives pressed at high temperatures.