When the oil makes contact with the back of the throat, the bitterness will force a cough. Bitterness is considered to be a desirable trait. Olive oil is judged like wine, by its organoleptic properties . These include color, bouquet and taste . All three properties depend on the ripeness of the olives when harvested, how they were kept and how the oil was extracted.
Color is tinged green by the chlorophyll of green olives or yellow by mature olives.
The amount of carotene determines how yellow the oil may become. As the oil becomes oxidized a red tint will appear. Oil processed at high temperatures, improperly stored, chemically extracted or exposed to light will lose these ephemeral compounds. Tasting for trade classification is performed by the International Olive Oil Council 's accredited Tasting Panels using a limited number of descriptors or indices, which are used to screen out oils that have been improperly produced. Until November 1996, in official sensory assessment, the tasters first sought just six types of defects.