Olive Oil Vocabulary
Here are the most commonly used terms to describe taste, quality and purity of olive oil.
SENSORY TERMS
Tasters describe the positive attributes of olive oil in the following terms:
Fruitiness: Pleasant spicy fruit flavors characteristic of fresh ripe or green olives. Ripe fruit yields oils that are milder, aromatic, buttery, and floral. Green fruit yields oils that are grassy, herbaceous, bitter, and pungent. Fruitiness also varies by the variety of olive.
Pungency: A peppery sensation, detected in the throat, and a positive characteristic of olive oil. It is a chemical irritation, like the hotness of chilies, and equally appealing once you get used to it. Pungency can be very mild—just the tiniest tingle—or it can be intense enough to make you cough. Olive oil experts will sometimes refer to a one, two, or a three-cough oil.
Bitterness: A mostly pleasant acrid flavor sensation on the tongue. The third positive attribute of olive oil, in addition to fruity and pungent. Bitterness, like pungency, is also an acquired taste. Bitter is a prominent taste in fresh olives and since olive oil is made from uncured olives, varying degrees of bitterness can be found. Oil made from riper fruit will have little to no bitterness, oil made from greener fruit can be distinctly bitter.
WAX CONTENT It is used to identify the presence of pomace oil and is determined by gas chromatography. Refining processes can more easily eliminate aliphatic alcohols, but waxes are more difficult to remove. Wax content of oils is higher in pomace oil, because pomace contains a greater proportion of fruit skin where most of the waxes originate.
TOTAL PHENOL It is the aggregate measure of polyphenol content of the olive oil. As polyphenols are a key antioxidant component in olive oil, Total Phenol is an indicator of the oil’s potential shelf life, its style and health benefits. Total Phenol in olive fruit before harvest can help select optimal harvest time to maximize polyphenol content in oil. Total Phenol is normally expressed as milligram equivalent of Gallic (or Caffeic) acid per kilogram of oil (mg/kg).
TRANS ISOMERS Illicit industrial procedures, which tend to mask seed oil in order to enable its use in mixtures with olive oil (e.g. de-sterolization), cause some modifications in the structure of the product fatty acids: In particular, they generate trans isomers. In olive oil, trans isomers are normally present in very low concentrations. Higher levels are an indication of unjustified industrial practices. The determination of trans isomer content is carried out through special gaschromatographic analysis.
INDICATORS OF QUALITY AND PURITY
A series of physical or chemical tests reveal the quality and purity of olive oil. The following terms are most commonly used to describe results of those tests:
ACIDITY It is a measurement of hydrolytic breakdown of the fatty acid chains, liberating free fatty acids, and is a crude indicator of the quality of the fruit and its handling procedures prior to milling. Results are presented as grams of oleic acid per 100 grams of oil (commonly known as percent of free fatty acidity). Freshly pressed oil, made carefully, without the use of excessive heat, from sound, healthy, freshly picked olives, normally has a pretty low acidity, well under 0.5% FFA. Extra virgin olive oils have less than 0.8% FFA.
PEROXIDE VALUE It is a crude indicator of the amount of primary oxidation that has occurred, forming peroxide compounds within the oil. Peroxide value (PV) is measured in a testing laboratory and expressed as milliequivalent of free oxygen per kilogram of oil (meqO2/kg). High quality extra virgin olive oils have a peroxide value of less than 10meqO2/kg. In order to be extra virgin, olive oil must have less than 20meqO2/kg. Olive oil with high peroxide value may not keep well.
UV ABSORPTION Ultraviolet spectrophotometric analysis is a more delicate manner to indicate oxidation and investigate changes in the structure of fatty acids. Ultraviolet Absorption (UV) at 232 nanometers (K232) is useful to evaluate old oils, especially when age or storage is in question. Ultraviolet Absorption (UV) at 270 nanometers (K270) is useful to evaluate virgin olive oil purity, especially when provenance is in question. Refined oils or blend of olive oils have higher absorption values than virgin oils. The index DK is a criterion of discrimination between a bad quality virgin olive oil and a virgin olive oil adulterated with refined olive oil.
SOURCES: www.agbiolab.com, www.easreth.gr, www.internationaloliveoil.org, www.minagric.gr, www.soilzone.com, www.prosodol.gr, www.oliveoil.gr, www.oliveoil.org, www.oliveoilsource.com, www.oliveoiltimes.com, www.olivetreeroute.gr, www.wikipedia.org, www.wix.com
