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Frequently Asked Questions



What is olive oil?

Olive oil is the oil that comes from the processing of olive fruits.

Every olive oil produced in the mill is called virgin until it is categorized through physicochemical and organoleptic analysis (smell and taste). Virgin olive oils are obtained from the olive fruit, exclusively by mechanical methods or other natural treatments and under conditions that do not cause alterations in their natural composition. Virgin olive oil has not undergone any treatment other than washing, crushing, malaxing, centrifugation and filtration.


How is olive oil is made?

The first important step is the careful collection of olives from the tree. The method of harvesting and whether it injures the fruit is the first step that determines the quality of the olive oil that will be produced. The traditional way of harvesting, that is, beating the branches with sticks so that the olives fall to the ground, has been proven to injure the fruit and the tree, leaving it exposed to fungi and bacteria (which penetrate its wounds). A careful collection of olives is necessary to ensure the quality of the final product. The most common way of harvesting is with vibrating tools or machines so that the fruit falls on the oilcloth without being injured. Workers should be careful not to step on the fruits. Then the olives should be put in plastic crates and not in sacks (with the pressure the fruit is injured, it does not breathe, fermentations start and the quality of the olive oil deteriorates) and they are transported to the oil mill as soon as possible (maximum 8 hours). Then the leaves are being removed, the fruit is washed and goes to the crusher. The crusher crushes the fruit and the pit and creates a paste. This paste is then passed into the malaxer where is being kneaded for a few minutes (usually not more than 30 and at a temperature no higher than 27oC). This stage is necessary for the decomposition and rupture of the cell walls that hold the oil drops but also for the unification of the oil droplets into larger drops (this is the reason that if one squeezes an olive he will not get olive oil because the oil drops are "locked" inside the cells and need special processing to be released). The action of enzymes plays a major role in this whole process, as well as the mechanical action by the fragments of the pit in the paste.

This paste is then pumped to the decanter where centrifugation will separate the liquids (olive oil-water) from the solids (pit, flesh). The next step is to separate the olive oil from the water (vertical separator). In this phase, we get the olive oil we consume but in an unfiltered form. If the producer wants to filter his olive oil, the most appropriate time is immediately after its production. Filtration removes moisture and solid residues and increases the shelf life of olive oil.


What are the quality characteristics of olive oil?

For an Olive Oil to be included in a category must undergo physicochemical and organoleptic analysis.

The physicochemical parameters that are examined and play a very important role in the quality of olive oil are free acidity, the number of peroxides, spectrophotometric absorption in ultraviolet (K232, K270, DK), impurities (insoluble in petroleum ether), traces of metal, the alkyl esters.

Organoleptic Analysis is the detection and description of the qualitative and quantitative olfactory-taste characteristics of virgin olive oil, using the human senses, and its classification according to its organoleptic characteristics. The method uses a group of selected and trained testers and is applied only to the classification of virgin olive oils according to the perceived intensity of the defect which is perceived with the greatest intensity and the presence or not of fruity.

The organoleptic analysis examines whether the olive oil has defects and its positive characteristics are also analyzed. Some of the defects are related to bad practices of harvesting and storage before milling (fusty, winey, musty), some to bad practices in the oil mill (burnt, metallic), and some due to poor storage practices (rancid, muddy sediment).

There are three positive attributes of olive oil. Fruity, Bitter and Pungent/Spicy.

Fruity: is the set of olfactory senses - characteristics of olive oils, which depends mainly on the variety of the olive and comes from healthy and fresh olives, ripe or unripe. It is perceived by smell and / or by the retronasal area.

It can be unripe fruity or ripe fruity. This attribute is the most important in the organoleptic analysis because if it is not perceived, the tested olive oil will not be classified as extra virgin or virgin.

More simply, the fruity of olive oil is its aroma, the aroma of the fruit of the olive. An experienced taster, in addition to determining its intensity, will also recognize in it the characteristic aromas of each variety. For example, freshly cut grass, tomato or tomato leaf, artichoke, citrus fruits, apple, banana, almond, various aromas of herbs or spices, etc.

Bitter: the characteristic taste of olive oil obtained from green olives or from olives that begin to change their color and which is perceived by the taste buds of the back of the tongue. It can be enjoyable or not, depending on the intensity. However, in any case, is it not considered a defect and is a result of the action of phenolic compounds present in olive oil.

Pungent/Spicy: intense kinesthetic sensation, characteristic of oils produced at the beginning of the harvesting season, mainly from green olives, which can be perceived throughout the oral cavity, especially high in the throat as a burn. It spreads throughout the oral cavity and is eliminated a few seconds after the tasting. Sometimes it can cause coughing or tears in the eyes. We should not confuse this feeling with that of the rancid olive oil where the burning is felt lower in the neck (chest), it is very annoying and is maintained for a much longer time (bad aftertaste). The spicy also depends on the presence of phenolic compounds. Its intensity decreases during the ripening of both the fruit and the olive oil.


Does the color of the olive oil play a role in its quality?

The color of olive oil is not a quality criterion. It ranges from tones of golden yellow to emerald deep green and depends to a large extent on the variety, the degree of ripeness of the fruit at harvest and whether the leaves have been processed together with the olives. Olive oil may have a very nice attractive green color but it may also have an organoleptic defect and high acidity so it is not an extra virgin. Expert olive oil tasters always taste in tinted glasses (blue or red) so that they do not see the color and have any bias.


How do the aromas of olive oil come about?

Aromas such as green olives, freshly cut grass, apple, banana, artichoke, oregano, etc. are found in many extra virgin olive oils. Many people think that these aromas are additives or endogenous to the olive fruit or that they have to do with the plants that grow around the olive tree. In fact, these aromas are volatile compounds produced by the activity of olive fruit enzymes during the extraction process of olive oil (eg. 3-hexenal gives the aroma of apple or hexanal the aroma of green leaf) and have to do with the variety, the ripening stage of the fruit, the climatic conditions of the specific year, the availability of water, the type of fertilization and the milling practices (mainly crushing and malaxing).

What is the acidity of olive oil?

The acidity of the olive oil shows the condition of the olive fruit from which the olive oil was produced. It is a chemical parameter that measures the free fatty acids found in olive oil. These fatty acids are "released" only when the olive fruit is damaged or attacked (eg olive fly, gloeosporium). If the olives are healthy, fresh and milled immediately after harvest, the fatty acid chains do not break and the acidity remains low (0.1-0.3%). The production of free fatty acids is due to the lipolytic action of the enzyme lipase, which is found in the olive fruit. This action takes place mainly before the extraction of olive oil and therefore the acidity changes very shortly after its extraction from the olive fruit. The acidity of olive oil can be detected only with chemical analysis and not with tasting. It is not the most important quality criterion because it is possible for an olive oil with low acidity to have a serious organoleptic defect. In that case, this olive oil cannot be characterized as Extra Virgin.


Which are the quality categories of olive oil?

Olive oil is available in the market in categories and we should read the label carefully when we are going to buy.

Categories of Edible Olive Oils (Regulation 2568/91 EU)

Extra virgin olive oil: its content of free fatty acids (acidity), does not exceed 0.8 g per 100 g (0.8%), has no organoleptic defects and has a detectable fruity.

Virgin olive oil: Olive oil whose acidity does not exceed 2.0%, has a small organoleptic defect (below 3.5, in a scale from 1 to 10) and a detectable fruity.

Olive oil - consisting of refined olive oils and virgin olive oils.

This oil is obtained by mixing refined olive oil (which has gone into industry and through processing has been neutralized, deodorized, discolored) and virgin olive oils, the acidity of which does not exceed 1.0%.

Pomace oil

This oil is obtained by mixing refined pomace oil and virgin olive oils, the acidity of which does not exceed 1,0%.


Extra Virgin Olive Oil is the best olive oil for consumption. It has the highest nutritional value and gives greater taste pleasure since it retains all its aromas.


Which are the types of olive oil;


Various types and not categories of olive oil are:


-Organic/Bio olive oil

- Cold extracted or unheated olive oil (extracted at temperatures below 27oC)

- Fresh or Early Harvest Oil

- Olive oil with aromatic plants (flavorings, dressings)

- Olive Oil of Protected Designation of Origin (PDO) (has the special organoleptic characteristics of the area that it is produced)

- Olive Oil of Protected Geographical Indication (PGI) (has the name of the region to which it owes its special reputation and in which it is produced)


What is Early Harvest?

Early Harvest refers to the olive oil produced from green olives that have been harvested early from late September to mid-late October (depending on the variety, the region, the climatic conditions, etc.). Its color is intense green and has a more bitter and spicy taste due to its high content of phenolic compounds. To take advantage of its high nutritional value but also its unique taste to the fullest, one should consume it within a maximum of 2-3 months.


Is unfiltered olive oil better?

Unfiltered is the olive oil that after its final separation (in the oil mill) does not go through the filtering phase. This means it retains moisture and solid residues. Over time, sediment will form inside the storage container. The fermentation of this sediment gives the well-known organoleptic defect called muddy sediment. The sediment and moisture together degrade the quality of olive oil. Unfiltered olive oil may have a higher percentage of phenolic compounds than filtered (depending on how it is filtered) but it is more sensitive to oxidation and fermentation resulting in its quality deterioration very quickly and shorter shelf life. It should be consumed within a month of its production.


What is high phenolic olive oil and what are its health benefits?

High phenolic olive oils are those olive oils that contain more than 250 mg/kg of phenolic compounds and according to EU regulation, 432/2012 can have a health claim which is written on the label. This claim can only be used for olive oils which contain at least 5 mg of hydroxytyrosol and its derivatives (eg oleuropein and tyrosol complex) per 20 g of olive oil. Olive oil phenols help protect blood lipids from oxidative stress and to achieve this beneficial effect the consumer should consume daily 20 grams (2-3 tablespoons) of high phenolic olive oil. These olive oils are considered a dietary supplement and due to their high content of phenols, they have a more bitter and spicy taste than all the others. It is recommended to consume them raw.


What should I look for on the olive oil label?

On the packaging of olive oils that are sold in the retail stores, the following must be indicated:


  • The brand name of the product

  • Information about the olive oil category

  • The determination of origin

  • The net amount of content in units of volume

  • The name or trade name and address of the manufacturer or packaging company

  • The date of minimum product shelf life

  • The batch number

  • Storage conditions

  • The approval code of the packaging plant


Terms such as premium, supreme, high-end, exceptional, luxury, etc. imply that the product belongs to some other category higher than extra virgin olive oil, which does not exist.

If you love bitter and spicy extra virgin olive oils that contain more phenolic compounds then it would be good to choose from olive oils with the indication "Early Harvest" or those with a health claim indication. Or if you are looking for organic olive oils, the label must have the BIO indication and certification.


How can I try the olive oil I buy at home?

Even if one has not attended a tasting seminar, one can start at home and smell and taste the olive oil before adding it to the food. Try the olive oil you just bought in the following way:

Follow the olive oil tasting steps to better appreciate all the aromas and flavors.


  1. POUR 15ml of olive oil in a small glass and cover with your other hand. 

  2. WARM the glass with your palm for a few minutes.

  3. SWIRL the oil around to coat the sides of the glass to release its aromas and uncover the glass.

  4. SMELL inhaling briefly and deeply, trying to capture the different sensations.

  5. SLURP a mouthful of oil and don’t swallow it immediately. Keep it in your mouth for a few seconds and inhale noisily from the sides of your mouth (to do so, put your tongue behind your front teeth and suck air from the sides of your mouth). Drawing air in heightens the flavor. Then breathe out through your nose.

  6. SWALLOW while concentrating on the flavor. Consider whether you perceive pungency as it goes down your throat and whether it makes you cough a bit.

  7. THINK ABOUT all the sensations you have felt. The fruitiness, bitterness, pungency, the different aromas, and flavors. Write down your observations, and then compare them with the other olive oils.

  8. CLEANSE your palate between olive oils with a thin slice of Granny Smith apple or a piece of plain bread. Drink some water.

  9. REPEAT!


Can I fry with extra virgin olive oil?
Due to its high content of antioxidants, monounsaturated fatty acids and vitamin E, olive oil retains its composition at high temperatures and does not degrade easily creating harmful by-products. The most suitable frying temperature is 180 ° C, where the food is cooked without burning. Extra virgin olive oil is the only vegetable oil that can be used up to 4 - 5 times if the temperature does not exceed 220 ° C. We should always remove the remaining fried food and store it in a glass container. If you do not have a fryer with an adjustable temperature, you will need a thermometer to check the temperature before placing the food in the pan and during frying. In contrast to extra virgin olive oil, the polyunsaturated fatty acids of seed oils, are very vulnerable to high temperatures, decompose and allow the creation of free radicals and by-products harmful to health from the first frying. If your pocket does not allow you to do all your cooking with Extra Virgin Olive Oil because it costs a little more, then you can take advantage of the different categories of olive oil. You can consume Raw Extra Virgin Olive Oil by sprinkling your salads and meals. You can cook and fry with Virgin Olive Oil, and you can also fry with Olive Oil (consisting of refined olive oils and virgin olive oils).


Can I cook all foods with one olive oil?

You can do it, of course, but this way you miss the opportunity to taste the unique aromas that each variety brings and to create unforgettable combinations.

For the lovers of gastronomy and good extra virgin olive oil, one variety in the kitchen is not enough since each variety has different flavors and aromas and ideally pairs with different foods. Intensities also play a very important role in the gastronomy of olive oil. The intensity of the fruity, the bitter and the spicy. Apart from the type of variety, the time of harvest and milling of the olives plays an important role in the intensities and aromas of the olive oil. Therefore the same variety if harvested and milled at the beginning of October or at the end of December, the olive oil produced will have different characteristics. High-intensity bitter and spicy olive oils for example pair very well with salads of boiled vegetables, grilled meat, or chicken while a sweeter olive oil better highlights the fine aromas of fish and seafood and pairs perfectly with desserts such as yogurt or ice cream. Therefore, it is important to know that one olive oil can exalt some culinary creations or to degrade them in taste (especially if it also has an organoleptic defect). Ideally, three extra virgin olive oils of different intensities-varieties would be perfect to exist in every professional and home kitchen.



How to store olive oil?

The fresher the olive oil, the better. Olive oil has five major enemies that undermine its quality and preservation: Oxygen (air), light, high temperature, time and packaging material that comes into contact with the product (e.g. plastic). Therefore, store in tinted glass bottles or stainless steel containers, away from the stove, and sunlight, in a dark and cool place (12-18 ° C and away from detergents!) Consume it in a short time. The shelf life of olive oil is 12-18 months from the date of packaging and concerns sealed bottles, when the bottle is opened the olive oil should be consumed within 2-3 months at most. If you buy a 17-liter tin (which is not recommended and is normally prohibited) make sure to transfer the olive oil in smaller bottles with the characteristics we mentioned. Because olive oil is so sensitive to oxidation (light, air, high temperature) when we go out to eat we never add olive oil to our salad from the classic oil and vinegar we can find on the table (normally it is forbidden and should not be on any restaurant table) and ask the waiter for olive oil in individual packaging or a non-refillable bottle. If there is a charge, do not hesitate to pay it. We are used to paying for water and not for olive oil, whose complex production process and high nutritional value make it more valuable anyway.


Text by Anita Zachou, Agricultural Engineer & Expert Olive Oil Taster by Jaen University

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