International Olive Oil Council
Sensory Assessment Tasting Terms
Positive Attributes or Defects in EVOO
Fruity - Set of olfactory sensations characteristic of good (unspoiled) fresh olive fruit, either ripe or unripe. This attribute is perceived by smell, either directly or retro-nasally.
Bitter – Characteristic of oil obtained from unripe (green) olives, this is perceived on the back of the tongue. Note that bitterness is an important part of an oil’s balance of flavors.
Pungent – Peppery sensation perceived at back of the throat that is indicative of the oil’s freshness. Also a characteristic of pressing unripe olives.
Negative Attributes or Defects in EVOO
Unfortunately many things can go wrong when producing olive oil, and some defects are only detected through sensory (organoleptic) assessment. The most common defects are:
Fusty - Characteristic obtained from olives that were stored in piles prior to pressing, which causes an advanced stage of anaerobic (without oxygen) fermentation.
Musty - Moldy flavor in oils obtained when a large quantity of the olive fruit has developed fungi and yeast as a result of its being stored in humid conditions for several days. This defect is detected retro-nasally (through the back of the nostrils after swallowing).
Winey-Vinegary - Flavor that is reminiscent of wine or vinegar. This defect occurs due to aerobic (using oxygen) fermentation in olives which leads to the formation of acetic acid, ethylacetate and ethanol.
Muddy Sediment - Characteristic of oil that has been left in contact with sediment in tanks and vats. This defect occurs from storage conditions after the oil is pressed.
Metallic - Flavor that is reminiscent of metals. This occurs when the oil has been in prolonged contact with metallic surfaces during crushing. Nowadays it is unusual to find this defect because modern presses are made from stainless steel and do not react with the olives.
Rancid - Flavor in oils which have undergone oxidation. This is the most common defect; it can occur either before or after bottling and if a bottle, either opened or unopened, has been exposed to light and heat.
Other Defects, Which Are Less Common
Heated or burnt – Occurs when oil is exposed to excessive and/or prolonged heat during processing.
Hay-wood – Flavor of oil produced from olives that have dried out.
Greasy – Flavor reminiscent of diesel oil, mineral oil, or mechanical grease.
Vegetable water – Flavor acquired by prolonged contact with the vegetable water that is a by-product of pressing olives.
Brine –Obtained from olives that were brined (such as table olives) before pressing.
Esparto – Flavor obtained from using new mats made from esparto (a type of grass) when pressing olives.
Earthy – Flavor obtained from olives with dirt or mud on them that have not been washed prior to pressing.
Grubby – Flavor obtained from olives that have been attacked by the olive fly, which causes disintegration of the olives before they are harvested.
Frozen – Flavor obtained from olives that experienced heavy frost or prolonged cold temperatures before being harvested and pressed.