Positive and negative attributes of the virgin olive oils

What should we find when we taste an oil that has been extracted from the olives solely by mechanical or physical means?
First of all we must look for three positive attributes: fruity, bitter and pungent.

Fruity: is the totality of the pleasant fruit flavors characteristic of fresh ripe or green olives. Ripe olives generally yield oils that are milder, aromatic, buttery, and floral, while green fruits yield oils that are grassy, herbaceous, bitter, and pungent. The intensity and kind of fruitiness also varies with the variety of olive.

Bitter: is a typical attribute related to oils from fresh green olives, but it also depends on the variety of olives. It is a pleasant and non-persistent sensation on the tongue whose presence means that the oil is rich in poliphenols, natural and healthy antioxidants

Pungent: is a peppery sensation perceived in the mouth and especially in the throat, a sign of abundant poliphenols, peculiar to good, fresh extra virgin olive oil.

If something wrong happened during the production, extraction or storage phase of a virgin olive oil it may undergo damaging processes whose direct consequence is the presence of negative attributes.

Among them the most common are:

Fusty/muddy sediment: characteristic flavour of oil obtained from olives piled or stored in such conditions as to have undergone an advanced stage of anaerobic fermentation, or of oil which has been left in contact with the sediment that settles in underground tanks and vats and which has also undergone a process of anaerobic fermentation.

Musty-humid-earthy: characteristic flavour of oils obtained from fruit in which large numbers of fungi and yeasts have developed as a result of its being stored in humid conditions for several days or of oil obtained from olives that have been collected with earth or mud on them and which have not been washed.

Winey-vinegary: characteristic flavour of certain oils reminiscent of wine or vinegar.

Acid-sour: this flavour is mainly due to a process of aerobic fermentation in the olives or in olive paste left on pressing mats which have not been properly cleaned and leads to the formation of acetic acid, ethyl acetate and ethanol.

Rancid: flavour of oils which have undergone an intense process of oxidation.

Frostbitten olives (wet wood): characteristic flavour of oils extracted from olives which have been injured by frost while on the tree