Olive Oil 101: Which Type of Olive Oil Is Best for Cooking?

Due to generally low awareness about olive oil, many consumers often solely rely on their grocers’ choices of available olive oils. Reputable grocers carry a diverse range from one end of the quality spectrum to the other i.e., from extra virgin to olive pomace oil. Understanding the basics about olive oil empowers us to begin navigating and exploring the world of olive oils and to avoid the pitfalls laid by wily marketing labels and terms. In this post, we try to cover the olive oils you would see on your grocer’s shelves so that the next time you see a label you know exactly what it means.

Quality categorizations of Olive Oils

Every olive oil quality grade has its own flavour profile, magnitude of health properties and physicochemical profile. Olive oil methods and standards of categorization are set primarily by the International Olive Council for its member countries but there are producer countries that have set higher standards on some parameters such as Australia and New Zealand.

Categories of Olive Oil and Key Quality Parameters

Olive oil is usually classified by the extraction method and oil quality, with regards to taste and a standard set of chemical parameters. There are at least a dozen chemical parameters that are used in olive oil grading plus a sensory panel tasting protocol for extra virgin certifications. These assessments, while robust, results rarely appear on bottle labels as they are currently not required. Basic knowledge of some key parameters can help us be more discerning in our buying decisions.

The two important chemical parameters you’d want to learn about are free fatty acidity and peroxide value.

● Free fatty acidity (FFA) - a key parameter that measures the degree of fermentation that is brought on and aggravated by anything from olive tree diseases, poor olive picking practices to improperly stored olives before milling. The lower the FFA % the higher the quality of the oil.

● Peroxide value (PV) - assesses the initial stage of oxidation that has occurred even before the smell of rancidity can be detected. Unsaturated free fatty acids react with oxygen and form peroxides, which then generate volatile substances responsible for a typical rancid bad oil smell. Higher levels of peroxides also indicate deterioration of healthful contents like polyphenols, anti-oxidants and nutritional components like tocopherols and vitamin E. In sensory assessments, trained olive oil tasters look for the presence of the aromas of healthy olives (or fruitiness) and the absence of any defects in order to certify olive oil as Extra Virgin. Detectable defects are caused by fermentation and oxidation that has happened at any stage of olive oil production from agricultural through milling and bottling phases. Taste defects unfortunately are pervasive even in olive oils that have glowing lab results, therefore, both chemical and sensory tests are compulsory for extra virgin certifications.

Now let’s look at what these key parameters mean as it relates to the bottle labels you see on your grocers’ olive oil shelves:

1. Virgin Olive Oils

Olive oils that are produced through mechanical means are the most natural type of olive oil. They are simply obtained by pressing without the use of any chemical additions during extraction. Virgin olive oils are produced in this manner, in mills. Virgin olive oils are available in three variants and are classified based on quality.

a. Extra Virgin Olive Oil (EVOO)

This is the best commercial grade of olive oil. EVOO grade requires more tests and much stricter limits for each test. This type of olive oil comes with a sizable amount of polyphenols that are known to deliver anti-oxidative and anti-inflammatory properties for good health e.g., decreasing the risk of cardiovascular diseases and cancer. With a free fatty acidity level that is below 0.8%, it comes with a good aroma and taste and can be sold directly to consumers.

Polyphenols in EVOO make it taste bitter and pungent – therefore bitter and pungent are considered positive taste attributes. The phenolic content is measured as Total Polyphenol Count (TPC) to determine flavour intensity and extent of healthful phenols it contains. There is a globally common and regulated testing method done for EVOO, especially top-quality EVOO. While there are no specific limits of TPC globally applied, the higher the TPC the healthier and more robust flavours it contains. The TPC unit of measure is between 30 to 800 mg/kg and a good benchmark is >200mg/kg.

In terms of peroxide value, high-quality EVOOs can have PVs of no more than 11 milliequivalent/kg which is far lower than many other grades of olive oil namely other EVOO, virgin olive oil, pure olive oil etc. The greater the level of peroxide indicates the greater the oil has been damaged by oxidative free radicals and is higher in rancidity.

That is why top-quality extra virgin olive oil is best known for its superior taste and flavours - fruity aromas, a slightly bitter and pungent taste. It is hence often used in salads as a tasty dressing but actually has a very broad application in all manners of cooking. It is especially used in the budding culinary discipline of olive oil with food pairing.

Also, truly high-quality EVOOs fare better beyond EVOO IOC (International Olive Council) global limits by a lot e.g. free fatty acidity for EVOO as required by IOC is 0.8% but for high-quality EVOO is ~0.3%. Countries like Australia and New Zealand abide a stricter free fatty acidity (FFA) standard of no more than 0.5% for their EVOOs. For instance New Zealand’s Olivo olive oils are in the High Quality EVOO grade - Olivo’s 2021 harvest oil result was FFA 0.1%.

b. Virgin Olive Oil (VOO)

This olive oil is a grade lower than the extra virgin and is differentiated as Virgin Olive Oil and Ordinary Virgin Olive Oil. It comes with free fatty acidity between 0.8% and 2% and 2% to 3.3% respectively. VOO is also more rancid than EVOO with peroxide value lies within 20 milliequivalent/ kg. It is commonly mixed with refined olive oil which lacks flavour. The bottle label’s ingredients list rarely if at all, states the proportion of VOO used.

2. Lampante Olive Oil (non-edible)

The lowest grade of virgin olive oil: with free fatty acid content exceeding 3.3% by weight. It usually comes from badly conserved olives. And it has an unpleasant smell and taste. Thus, it is forbidden to be sold commercially to consumers and requires further processing at refineries to remove the defects before use. Lampante virgin olive oil is refined by treating it with heat, filtration, and/or chemical processes. The refining process, while improving the free fatty acid levels, destroys the majority of the polyphenols where the taste and health benefits of olive oil come from.

3. Refined Olive Oil

As the refined product of lampante virgin olive oil, it is very much without taste or color and is usually blended with virgin olive oil to provide some flavour and aroma before being sold to consumers. The blended refined olive oil is sold on shelves as olive oil or pure olive oil.

Lampante oil goes through 4 broad phases of refining:

● Purification or Degumming - waters and phosphoric acid are used to remove unwanted by-products e.g. gums, resins, phospholipids that may cause formation of mucilages (sediments in the olive oil). Desirable natural proteins of virgin olive oil are removed by the process as well.

● Neutralization with soda - level of acidity is lowered but a large amount of carotenoids (vitamin A components) is also removed.

● Bleaching or fading with activated clay at 100 celsius - substances giving the colour of the oil are taken out which also include the chlorophyll that contains beneficial health properties.

● Deodorizing at temperatures of 200 – 250 celsius - unpleasant odors and tastes are eliminated by heat and along with it, natural antioxidants like polyphenols.

4. Olive Oil or Pure Olive Oil

This is probably the most misleading label of all the olive oil categories that are commonly found on grocery shelves. Having an acidity of no more than 1%, olive oil/ pure olive oil is a blend of refined olive oil and virgin olive oil or EVOO. ‘Pure’ olive oil has some flavour and is fit for human consumption but without the complete health and taste benefits of extra virgin olive oil. For most parts, we do not know the proportion of virgin or extra virgin oil blended. As a product that contains refined olive oil (ROO), it has undergone the advanced stage of oxidation that is detectable in taste and therefore is of much poorer quality than EVOO. Therefore it is not a true alternative to EVOO.

5. Raw / Crude Olive Pomace Oil (chemically extracted olive oils)

Olive oils can also be extracted by chemical processes. Once the mechanically extracted olive oils have been drawn out from the olives, the solid remnants left behind by the process known as olive pomace still have residual olive oil. This residual olive oil can only be extracted through the use of chemical solvents.

After chemical extraction, a product known as raw olive pomace olive oil is obtained. Raw (crude) olive pomace oil needs refining and is not safe for human consumption.

Olive pomace oil is normally used to produce biomass fuel used for firing up home burners or furnaces.

6. Refined Olive Pomace Oil

Refined olive pomace oil is tasteless, odourless, colourless and deemed safe for consumption but no longer resembles the original product any longer and should be seen as a completely different product compared to virgin olive oils therefore is definitely not an alternative.

It is usually sold in large tins or plastic containers as cooking oil at much lower prices when blended with some virgin olive oil, labeled as Olive Pomace Oil. Crude Olive Pomace Oil is also used in cosmetics and toiletries usually marketed in a way that takes advantage of the healthy “halo” of olive oil.

Olive Oil on your grocer’s shelves

There is a widespread assumption that the best olive oils come from certain places like Spain and Italy. This is a myth. Both good and inferior olive oils can come from both countries and more. Also, you would be surprised to know many reputable grocers carry all of the fore-mentioned oils i.e. from EVOO to olive pomace oil on their shelves. A good way for us to be empowered and be more discerning to make the right choices is to know more olive oil facts and most importantly aware of how truly great olive oil should taste like since other grades of olive oil are incomparable in health properties and flavour to EVOO. If you want to get the full benefits of EVOO, never buy anything that doesn't say "extra-virgin" on the label.

You can always discover how great top-grade EVOOs taste with a certified olive oil sommelier. They are best equipped to take you through the world of extra virgin olive oil appreciation to enrich your knowledge and get yourself familiar with the quality you enjoy.