There are many attributes of olive oil that indicate poor quality like being rancid, fusty, musty or winey; but having a bitter sensation on the tongue or a back of the throat sting, is not one of them. In fact, it is one of the best indications of an extra virgin olive oil’s antioxidant and anti-inflammatory value. It is the flavenoid polyphenols in olive oil that contribute to a bitter taste and resistance to oxidation. These polyphenols are strong antioxidants and have been shown to provide a host of beneficial effects from healing sunburn to lowering cholesterol, blood pressure, and risk of coronary disease.
A recent study 1 conducted by scientists at the Monell Center also found that oleocanthal, a natural polyphenolic anti-inflammatory agent uniquely found in extra virgin olive oil, functions much the same way that ibuprofen, an over-the-counter non-steroidal anti-inflammatory drug (NSAID) does. According to the study, researchers also demonstrated that this receptor is spatially located at the back of the throat, which is exactly where the distinctive, irritating sting from olive oil is felt. This unique sensation and the accompanying “cough” are regarded among connoisseurs as indicators of high quality olive oil.
There are many beneficial phenol compounds, like hydroxytyrosol and tyrosol, that can be found in abundance in high quality olive oil. Chemical analysis has shown that there can be as many as 5 mg of polyphenols in every 10 grams of olive oil. Many other nut and seed oils have no polyphenols. The polyphenol content is determined by many factors including:
- Olive Varietal: Koroneiki olives, for instance have a very high level of polyphenols, while Arbequina’s content is low. The content of Frantoio olives is medium-high and that of Leccino medium.
- Time of Picking: Oil made from green (unripe) olives has more polyphenols than oil made from ripe olives. The polyphenol concentration increases with fruit growth until the olives begin to turn purple and then begins to decrease.
- Environmental Factors such as altitude, cultivation practices, and the amount of irrigation.
- Extraction Conditions: Techniques used to enhance yield, such as heating the paste, adding water, and increasing malaxation time, result in a loss of polyphenols.
- Storage Conditions: The type of containers and the length of storing are key factors in the oil’s polyphenol content. As oil sits in storage tanks or in a bottle, the polyphenols will slowly be oxidized and used up. Oils stored in stainless steel containers or dark glass bottles, in cool conditions, are much better protected against oxidation than those bottled in clear glass.
- Refining: Olive oil which is old, rancid, made from diseased olives, or has some other defect can be made palatable by refining. This is done by filtering, heating, charcoal, or chemical treatment to adjust acidity. Refined oils are low in tyrosol and other phenols.
To learn more about olive oil tasting, visit The Olive Oil Source's How to Taste section.
1 Monell Chemical Senses Center (2011, January 27). NSAID receptor responsible for olive oil's 'cough' and more. Retrieved February 2, 2011, from ScienceDaily.