6.3.1. Terminology of olive oil types

• Extra virgin olive oil (EVOO)^[14]: It is the highest quality of olive oil. It has superior flavor and aroma and is praised worldwide for its health benefits. For olive oil to be characterized as EVOO, certain criteria must apply as these have been defined by the International Olive Council (IOC) and the EU Commission Regulation (EC) No 2568/91:
• Low acidity levels: Free acidity level of no more than 0.8 grams per 100 grams.
• Organoleptic properties: Free from fusty/rancid aromas and fruitiness in its flavour.
• Production method: Free from excessive heat (less than 27°C or 80.6°F is acceptable) or chemicals; only mechanical extraction (cold-pressed or cold extraction) is accepted.

Image 9 – Olive oil distinctive branding example – Source: Freepik.com

These standards don’t define the necessary use of overripen olives, but the ripeness stage during harvesting plays an important role in the EVOO’s yield, shelf-life, flavour/aromas, and nutritional composition. Usually, top-tier EVOO is made using ripe olives (veraison stage, during which olives begin to turn from green to purple).

Image 10 – Glass bottles containing olive oil – Source Freepik.com

• Infused olive oil^[15]: Infused olive oil is a type of flavoured oil made by adding herbs, spices, fruits, or other aromatic ingredients to olive oil, allowing their flavours to saturate the oil over time.
• Lampante olive oil^[16]: It is the worst quality olive oil. It has an unpleasant taste and an acidity of over 2.0%, which makes it inappropriate for human consumption.
• Pomace olive oil^[17]: Also known as crude oil, it is extracted from the by-product of virgin olive oil production, meaning that it is extracted not directly from olives but from the olive pomace (hence the name). The term “olive pomace” refers to the solid remains (e.g. skin, pulp, pits) left after the cold extraction of virgin olive oil. Due to the low level of residual oil contained in pomace, it can only be extracted via the use of solvents and then refined. Using mechanical methods of extraction is not applicable. Free acidity levels in pomace olive oil must be ≤0.3%. Its taste is very neutral, and its colour is light yellow to golden.
• Refined olive oil^[18]: It is obtained from virgin olive oil that has defects (e.g. not the expected taste) or is high in acidity levels. Defective virgin olive oils are refined via the following methods:
• Bleaching: After heating (90-120°C) under a vacuum, absorbent materials such as activated clay are inserted into the oil to remove unwanted pigments, metals, soaps, or oxidation agents
• Deodorization: The oil is distilled under a high vacuum and very high temperatures (200-250°C) for approximately 30-60 minutes. This allows the removal of compounds like ketones, free fatty acids, or aldehydes, which are responsible for causing the bad odour.
• Neutralization: The oil is mixed with a strong alkali solution (NaOH), which results in the removal of free fatty acids to improve its taste and shelf life.

Free acidity levels in refined olive oil must be ≤0.3% (compared to ≤2.0% in virgin olive oil). Its colour is usually pale yellow to golden (unlike EVOO, which is green), and its flavour is very mild or neutral. Sometimes, it is blended with small amounts of virgin or EVOO to improve its taste, and when sold, it’s labelled as “Olive Oil” or “Pure Olive Oil”.

Image 11 – Olive oil in a laboratory vessel – Source Freepik.com

• Refined pomace oil^[19]: Pomace oil is refined, and that’s when refined pomace oil is made. When sold, it’s labelled as “Refined Olive Pomace Oil”. It is often blended with some virgin or EVOO to improve its taste and aroma.
• Virgin olive oil^[20]: When compared to EVOO, virgin olive oil is very similar, but their main difference lies in the acidity levels:
• Low acidity levels: Free acidity level of no more than 2.0 grams per 100 grams.
• Organoleptic properties: Like EVOO, although its taste and aromas are not as high quality.
• Production method: Like EVOO, its production is free from excessive heat (less than 27°C or 80.6°F is acceptable) or chemicals; only mechanical extraction (cold-pressed or cold extraction) is accepted.

Virgin olive oil does not require olives to have a specific stage of ripeness; it uses olives from green (unripe) to black (fully ripe). It lies within the producers’ preference to choose the desired ripeness stage based on the flavour, profile, and yield that they wish to achieve:

• 1. Green olives will produce virgin olive oil that is usually higher in antioxidants and has a bitter, peppery taste.
  2. Black olives will give a virgin olive oil that will have a fruitier taste and aroma but lower polyphenol levels.

6.3.2. Terminology of olive oil composition

• Acidity level^[21]: In olive oil, it refers to the level of free oleic acid expressed in grams per 100 grams. The lower the level of oleic acid contained, the higher the quality of olive oil is. High levels of a particular acid often signal oxidation or fermentation. The acidity level of olive oil is influenced by the quality of olives, its processing methods, and storage. Delays in processing or inappropriate storage can lead to high acidity levels and, therefore, compromise the overall quality of the oil. The only way to measure acidity is in a lab, and despite what many people think, it can’t be detected by taste.
• Monounsaturated fats^[22]: A type of healthy dietary fat, primarily in the form of oleic acid, which makes up 55–83% of olive oil. These fats help lower bad cholesterol (LDL), support heart health, and have anti-inflammatory properties.
• Oleic acid^[23]: a fatty acid that occurs naturally in various animal and vegetable fats and oils.
• Oleocanthal^[24]: A natural compound found in olive oil known for its strong anti-inflammatory properties, often compared to ibuprofen, and contributes to the oil's pungent, peppery taste.
• Peroxide index^[25]: It is a measure of olive oil’s freshness and quality, specifically indicating the degree of oxidation and the presence of peroxides (a class of chemical compounds).
• Polyphenols^[26]: Polyphenols in olive oil are natural antioxidants that contribute to the oil's stability, flavor, and health benefits, including anti-inflammatory and heart-protective effects. There are 25 polyphenols found in extra virgin olive oil (e.g. hydroxytyrosol, oleocanthal).
• Sterols^[27]: Sterols in olive oil are naturally occurring plant compounds, primarily β-sitosterol, that contribute to its health benefits and are used as indicators of oil quality and authenticity.