The Olive Tree

The olive tree is a medium-sized, very hardy tree, with roots that reach up to 6 meters, and around 400 varieties are known. Man has transformed and improved the characteristics of this tree over time, until he obtained the tree we call the cultivated olive tree today.
This is a tree that everyone knows, the mother of the olives that produce the olive oil we consume, is of the species Olea europea L, and within this species there are different varieties, spread across different olive-growing areas. The most important Portuguese varieties are Galega, Cordovil, Cobrançosa and Verdeal. However, there are also several foreign varieties grown in Portugal, some of the most common being Arbequina, Arbosana, Koroneki and Picual.
Due to its hardiness, the olive tree is often found in areas where no other plant could resist. However, when the olive tree is treated as a true crop, yields increase in quantity and quality.

Olive Oil Extraction

Olive oil is the fat that is naturally synthesized in olives as a reserve substance, helping to ensure the multiplication of the species. It provides the necessary energy during the period in which the olive, at this stage already freed from the mother tree, will germinate and give rise to a new plant.
Olive oil is obtained from olives exclusively by mechanical and physical processes. As it is the juice of a fruit, for it to be of good quality you must have fresh fruit, i.e. olives in perfect health and at the optimum point of ripeness.
Olive picking
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Transportation to the mill
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Premilinary operations
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Clean, washed and weighed olives
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Milling
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Olive paste
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Thermobating
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Beaten and heated olive paste
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Separation of solids and liquids
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Olive Oil + Water
Pomace
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Separation of Olive Oil
 
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Virgin Olive Oil
Vegetable water
 
 
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Storage
 
 
 

The olive tree blossoms in spring and the fruit begins to form. The fruit ripens and is picked during the fall and early winter, depending on the variety of olive and the region of the country. The olives can be harvested in different ways: by hand, by mechanical means of vibrating the tree or by harvesting machines.

The harvested olives are transported to the mill to be processed. The olives must be transported as quickly as possible in order to preserve their quality. The olives should be transported in rigid, open crates so that they don't undergo undesirable fermentation, which means no bags should be used. In addition, it is important to note that olives picked from the ground should not be transported together with those picked from the tree.

On entering the mill, the olives must be classified according to variety, whether they come from the soil or the tree, whether they are healthy or attacked by pathogens, in order to be processed separately according to class. In each class, the olives are ventilated so that the air currents separate the accompanying leaves and then washed with running water.
At this stage, a sample is taken to the laboratory, weighed, sorted and stored. The olives are separated into batches according to quality. Therefore, in order to obtain quality olive oil, the olives must be processed within 24 hours of being picked at the latest.

Grinding consists of crushing the olives into a paste. In the past, stone mills (mós or galgas) were used, but nowadays we use metal hammer mills.

The paste is then beaten and heated in a thermo-blender to a maximum recommended temperature of 30ºC, in order to facilitate the separation of its different components.

Once the mass has been properly beaten and heated, the solid phase (the pomace) is separated from the liquid phases (the olive oil and the vegetation water). This operation is carried out using pressure systems (classic), centrifugation (continuous) and/or percolation or selective filtration (Sinolea).
• Classic system (discontinuous) - The mass is placed between the mats and subjected to pressure in order to separate the oily must (mixture of olive oil and water) which is then allowed to decant in order to obtain, by density difference, the olive oil.
• Continuous System (by centrifugation)
3 stages - Water is added to the beaten olive paste and passed through a horizontal centrifuge where the solid part is separated from the oily must. The must is transported to a vertical centrifuge where the olive oil is separated from the vegetation water.
2 stages - This process is practically the same as the previous one, except that instead of adding water to the mash, the water in the mash comes out together with the solid phase.

The olive oil obtained is stored in tanks until it is marketed. The material in the tanks must be inert.

Olive Oil Quality

Chemical analysis and sensory analysis are used to assess the quality of olive oil.
Acidity is the amount of free fatty acids, expressed as a % of oleic acid. It is higher the more the fruit is degraded and the worse the conditions under which the oil is extracted and stored. The acidity percentage of an olive oil has nothing to do with its taste.
The peroxide value checks the initial oxidation of the oil and its deterioration.
Ultraviolet absorbance is used to detect abnormal components in olive oil.
Olive oil is the only product with a compulsory organoleptic test. The organoleptic characteristics are evaluated by a panel of expert tasters, observing sensations detectable by the senses and related to aroma and taste.
Curiously, the color of an olive oil is not synonymous with quality which is why the professional tasters use blue glasses, so as not to be influenced by its hue.
In addition, the oil is heated slightly to a temperature of approximately 28º C so that the volatile components, which give the oil its aroma and flavor, are released more easily. The aim of the organoleptic test, in addition to assessing the positive attributes of an oil, is to check whether or not it has organoleptic defects.
The main positive attributes are:
• Fruity: A set of olfactory sensations, depending on the variety of olive, by direct and/or retronasal route, characteristic of olive oil obtained from healthy and fresh fruit, whether green or ripe.
• Bitter: An elemental taste characteristic of olive oil obtained from unripe olives or olives at an early stage of ripeness, felt by the goblet papillae that make up the V lingual.
• Spicy: A tactile sensation of stinging throughout the oral cavity, especially in the throat, characteristic of olive oil produced at the beginning of the season, mainly from olives that are still green.
The most common organoleptic defects are:
• Tulha/Borra: “Flavour” characteristic of oil obtained from olives that have been piled up or stored in conditions that have put them into an advanced state of anaerobic fermentation, or oil that has remained in contact, in underground tanks and reservoirs, with decanted matter that has also undergone a process of anaerobic fermentation.
• Moist-earth mold: “Flavour” characteristic of oil obtained from olives attacked by molds and yeasts as a result of storing the fruit for several days in damp conditions or from olives harvested with soil or mud that has not been washed off.
• Rancidity: “Flavour” of olive oils that have undergone an intense oxidation process.

Olive Oil Classification

According to current legislation, the designations and definitions of olive oil and olive-pomace oils are as follows:

Olive oil obtained from the fruit of the olive tree solely by mechanical or other physical processes, under conditions that do not alter the oil, and which has not undergone any treatment other than washing, decantation, centrifugation and filtration, excluding oils obtained with solvents, with chemical or biochemical adjuvants or by re-esterification processes and any mixture with oils of another nature.
Virgin olive oils are classified and named as follows:
a) Extra virgin olive oil – Virgin olive oil with a free acidity, expressed as oleic acid, of no more than 0.8 g per 100 g and with the other characteristics in line with those laid down for this category.
b) Virgin olive oil – Virgin olive oil with a free acidity, expressed as oleic acid, of no more than 2 g per 100 g and the other characteristics of which comply with those laid down for this category.
c) Lampante olive oil – Virgin olive oil with a free acidity, expressed as oleic acid, of more than 2 g per 100 g and/or with the other characteristics which comply with those laid down for this category.

Olive oil obtained by refining virgin olive oil, with a free acidity expressed as oleic acid of no more than 0.3 g per 100 g and with the other characteristics which comply with those laid down for this category.

Olive oil obtained by blending refined olive oil and virgin olive oil, excluding lampante olive oil, with a free acidity, expressed as oleic acid, of no more than 1 g per 100 g and with the other characteristics complying with those laid down for this category.

Commercial Types of Olive Oil

Extra Virgin Olive Oil - Superior quality olive oil with an intense taste and smell of healthy olives. It has no organoleptic defects and has an acidity of 0.8% or less. It is suitable for direct consumption and ideal for seasoning raw food. Extra virgin olive oil with a milder flavor is ideal for dressing salads and foods with a milder flavor, as well as for confectionery. On the other hand, it has a more intense flavor and goes better with more strongly flavored foods, and can be used to make some sauces.
Virgin Olive Oil - Good quality olive oil, with the taste and smell of healthy olives, with acidity equal to or less than 2%, suitable for direct consumption and suitable for roasts, soups, stews or marinades.
Olive oil - composed of refined olive oil and virgin olive oil - This is refined olive oil, enriched with virgin olive oil, aromatic and fruity, with an acidity level of 1.0% or less. It is ideal for frying due to its high resistance to high temperatures. It is cheaper, retains the nutritional value of olive oil and has a very high smoke point, which allows it to be used more often. It also forms a crust on the surface of the food, which prevents the olive oil from penetrating inside. Using olive oil for frying results in drier and more appetizing fried foods.

PDO’s

A PDO (Protected Designation of Origin) is a geographical name that designates and identifies a product originating in a place or region, whose quality or characteristics are essentially or exclusively due to the specific geographical environment, including natural and human factors, and whose production stages take place in the delimited geographical area.
Protected Designations of Origin
PDO's Varieties Olive Oil Characteristics
Trás-os-Montes Olive Oil Verdeal
Madural
Cobrançosa
Cordovil
5% other nationals		 Balanced olive oils, with a fresh fruit aroma and flavor that is sometimes almondy. Remarkably green, bitter and spicy.
Beira Interior Olive Oil Beira Alta Olive Oil
Galega
Cornicabra
Carrasquenha
Others
Galega
Bical
Cordovil		 Light yellow to slightly greenish olive oil. Fresh fruit flavor. Mild.
Beira Baixa Olive Oil
Galega
Bical
Cordovil		 Light yellow to slightly greenish olive oil. Fresh fruit flavor. Mild.
Ribatejo Olive Oil Galega
Cobrançosa
Others		 Slightly thick, fruity olive oil with a golden yellow color, sometimes slightly greenish. Markedly sweet and smooth taste.
Norte Alentejano Olive Oil Galega
Blanqueta
Cobrançosa
Azeiteira
Carrasquenha
Redondil		 Olive oil with low to very low acidity, slightly thick, fruity, with a golden yellow color, sometimes greenish, and a mild aroma and taste.
Alentejo Interior Olive Oil Galega
Cordovil de Serpa
Cobrançosa
Others		 Golden yellow or greenish olive oil with a soft fruity aroma of ripe and/or green olives and other fruits such as apples and figs. Very sweet.
Moura Olive Oil Verdeal
Cordovil
Galega		 Low to very low acidity olive oil, greenish yellow in color with a fruity aroma and taste. Bitter and spicy.

Curiosities

Did you know that...

• All olives are black when ripe;

• It takes an average of 5 to 6 kg of olives to extract 1 liter of olive oil;

• The degree of acidity is not related to the aroma and taste of olive oil. Acidity represents the % of free fatty acids in an oil and fatty acids have no aroma or taste;

• The aroma of an oil is given by a set of substances that exist in olives in small quantities (minor compounds). These vary with the variety of olive and its degree of ripeness;

• The color of olive oil is not directly related to its quality. A green olive oil comes from olives that are still green, so it has a more intense flavor. A golden olive oil comes from ripe olives and therefore has a milder flavor;

• Olive oil, unlike wine, does not improve with time. When well-conditioned, it can be kept without altering its characteristics for 18 to 24 months from extraction;

• Olive oil yields more than other vegetable fats, both cold and hot;

• Olive oil should be stored in dark glass containers or in tinplate or stainless steel containers. It should be kept in a cool, dark place and away from products with strong smells to prevent it from absorbing them;

• When subjected to very low temperatures, olive oil can solidify. However, it will regain its original appearance when it returns to room temperature and will not lose any of its characteristics;

Glossary

A

• Absorvência no Ultravioleta (Ultraviolet absorbance) (K270, K232, ∆K): Used to detect abnormal components in an olive oil.

• Acidez (Acidity): Percentage of free oleic acid in olive oil. It is not related to taste.

• Análise Organoléptica (Organoleptic Analysis): Analysis carried out to characterize the aroma and taste of an oil. Mandatory by law.

• Água russa (Vegetable water): Olive vegetation water, i.e. the water inside the olives. It is very polluting.

• Azeite (Olive oil): A yellowish-green liquid fat that is obtained by physically extracting it from olives.

• Azeite de Agricultura Biológica (Organic olive oil): Olive oil from olive groves grown in accordance with the organic production method, as laid down in European regulations. This production method imposes several important constraints aimed at protecting the environment.

• Azeitona (Olive): Fruit of the olive tree (Olea europea, L.), an ovoid drupe.

B

• Bagaço de azeitona (Olive pomace): By-product obtained from the extraction of olive oil. It includes the water used to make up the olives, the water used to add and wash them and a variable percentage of solid product (skin, pulp and olive stone). The amount of water present in this by-product depends on the olive oil extraction method used.

• Borras (Dregs): Impurities in olive oil which, after some time, end up settling at the bottom of the containers in which it is stored.

C

• Capacho: An object in the olive oil mill, in the shape of a flat, thin disk, made of vegetable or synthetic fibers, on which the olive paste is distributed in order to be squeezed in the press.

• Cor (Color): The color of olive oil varies from yellow to green. It is not related to the quality of the oil. Olive oils obtained from riper olives are more yellow, while oils obtained from greener olives are more green.

D

• DOP (PDO): Protected Designation of Origin. European certification that guarantees that the oil originates in a delimited geographical area with characteristic soils and climate and is made exclusively from olives from certain varieties of olive trees.

E

• Extração a Frio (Cold Extraction): Olive oil extracted at a temperature below 27º.

I

• Infernos ou ladrões (Infernos or thieves): Name given to the deposits where vegetable water is stored.

• Índice de Peróxidos (Peroxide Index): A parameter used to check the initial oxidation of olive oil and its deterioration.

L

• Lagar (Mill): Place where olives are processed in order to extract olive oil.

• Lote (Batch): A group of sales units of a foodstuff produced, manufactured or packaged under practically identical circumstances. This indication makes it possible to find out details about the production and filling of the product, such as the date of manufacture and the origin of the raw materials used.

M

• Maquia: Quantities of olive oil that the miller retains for himself in return for the services he has provided to the olive growers.

• Monovarietal: Olive oil obtained from a single variety of olive.

O

• Óleo de bagaço de azeitona (Olive pomace oil): Oil extracted from olive pomace using chemical processes.

• Oliveira (Olive tree): The olive tree is known scientifically as Olea europaea L., family Oleaceae. They are low trees with twisted trunks native to the eastern part of the Mediterranean Sea.

P

• Painel de provadores (Panel of tasters): Group of tasters specially trained to carry out the organoleptic characterization of olive oil and to score it.

• Primeira pressão a frio (First cold pressing): Term used for olive oils obtained by pressing at a temperature below 27º.

T

• Teor em Ceras (Wax content): Parameter analyzed to verify the genuineness of an olive oil.

V

• Variedade (Variety): Different types of olive trees which, despite belonging to the same species, have some significant differences.