How Cretan Olive Oil is Made

How Olive Oil Is Made

The craft of turning olives into oil has been honed in the Mediterran ean region over thousands of years, and techniques have been passed down from generation to generation . The process is truly a regional art. The method used in Greece is different from the one used in Spain, and each individual grower might have a unique way of tending the trees and producing the tasty liquid gold.

Mediterran ean olive trees must mature for several years before they produce olives. Careful pruning optimizes the number of olives a single tree will bear. A meticulous hand is necessary because it takes at least ten pounds of olives to produce one liter (about four cups) of olive oil.
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About 10 pounds of olives will produce one liter of oil.

Hundreds of olive varieties exist, but only several dozen are grown commercial ly around the world. Some varieties are bursting with health- promoting polyphenol s, while others contain few. The type of olive used to make any particular bottle of oil is rarely listed on the label. However, for those labels that do have the informatio n, the following table, which shows which olives are richest in beneficial polyphenol s, will be helpful.

The time at which olives are harvested also plays a major role in flavor and polyphenol content. The peak time is a short period right as the olives ripen. Olives are at their prime for only about two or three weeks. Healthy compounds then rapidly diminish over the next two to five weeks.

Picking Particular s

It takes quite a bit of work to coax oil out of olives. Traditiona lly, trees were shaken or beaten with sticks to make the olives drop to the ground. Such tough treatment is not good for olives, however. Tumbling out of a tree and plopping onto the ground causes bruising.

Soft fruits, such as peaches and plums, wouldn't take kindly to this type of treatment; they would bruise, too, and we would never think of harvesting them this way. Olives are also soft fruits that should be treated delicately because once they bruise, the beneficial oils within start to degrade.
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What Color Says
About Olive Oil
Olive oils made from unripe, green olives have a light- to deep-green color. Oils made from ripe olives tend to be a golden- or light- yellow color. The color of olive oil is not an indicator of quality in relationsh ip to culinary uses; however, if you're looking to get the most polyphenol s from your olive oil, choose one with golden or yellow tints because they come from ripe olives and may contain more healing compounds.

Some olive oil labels declare that their bottles' contents are made from handpicked olives. This typically denotes a better- quality oil. Some growers separate their olives into "ground" olives (those collected from the ground) and "tree" olives (those picked from the tree) and use them for different grades of oil. Many large- scale growers use a tree- shaking device and set up nets beneath the trees that catch the olives before they hit the ground.

Growers must be careful when transporti ng olives from the trees to the processing plant. Olives are best carried in shallow containers so they don't pile up too deeply and crush one another. Any damage to the olives can trigger oxidation and fermentati on, which create an "off" flavor. Olives should be processed soon after harvest because storing them also diminishes their quality.

Press Time

After olives are picked, any leaves, twigs, and stems are removed, and the olives are washed. Then it's time for pressing. Back in the old days, processors used stone or granite wheels to crush the olives.

Today, stainless steel rollers crush the olives and pits and grind them into paste. The paste then undergoes malaxation , a process in which water is slowly stirred into the paste. Malaxation allows the tiny oil molecules to clump together and concentrat e.

The mixture is stirred for 20 to 40 minutes. Longer mixing times increase oil production and give the oil a chance to pick up additional flavors from the olive paste. However, the mixing also exposes the oil to air, producing free radicals that poorly affect its quality.

Modern systems use closed mixing chambers filled with a harmless gas to prevent oxidation. This method increases yield and flavor and preserves quality. The mixture may be heated to about 82 degrees Fahrenheit , which further increases yield but does allow some oxidation. This temperatur e is low enough to be considered "cold pressed."

Next, the paste is put on mats and further pressed or sent through a centrifuge (a compartmen t that is rotated on a central axis at extreme speed to separate materials) . When the centrifuge spins, the olive paste remnants are pushed to the sides of the compartmen t cylinder while water and oil are extracted from the center of the centrifuge . The oil and water are later separated.

The solid material that remains after the extraction of the oil is called pomace, and it contains residual oil. Some manufactur ers will use steam, hexane, or other solvents to squeeze more oil out of the pomace. This low- quality oil must be labeled as pomace oil.

Oil may then be refined, bleached, and/or deodorized . Refining reduces acidity and any bitter taste. Bleaching removes chlorophyl l and carotenoid s (naturally occurring pigments that give plants their colors) and possibly pesticides , resulting in a light- colored oil with fewer nutrients. Deodorizin g removes the fragrant aroma of the olive oil.

In the manufactur ing plant, oil is stored in stainless steel containers at about 65 degrees Fahrenheit to prevent breakdown before it is bottled and shipped.

Lots of different types of olive oil come out of the presses. On the next page you'll learn what all the label terms mean and what's inside each of the bottles.

An Understand ing Olive Oil Labels

Here are some terms you might see on olive oil labels that describe extraction methods. The first two are cold- extraction processes. Olive oils processed by these methods retain the vitamins, health- boosting phytochemi cals, color, flavor, and aroma of the olives. The second two are heat- extraction processes. The heat used in these techniques takes a toll on olive oil. Excessive heat destroys many of the fragile nutrients and phytochemi cals and just about all of the color, flavor, and aroma.

Cold pressed. This method removes the oil from olives through pressing and grinding. For the oil to be labeled "cold pressed," the heat generated by friction from the grinding must not exceed 86 degrees Fahrenheit . (Other oils, such as safflower and canola, are sometimes cold pressed, but for those oils, friction temperatur es of up to 120 degrees Fahrenheit are allowed.)

Vacuum extraction . This is a cold- extraction method done in the absence of air and light at temperatur es as low as 70 degrees Fahrenheit . Olives are crushed and ground, then mixed with water and churned in a device that uses a vacuum. The process ensures no air is introduced into the system and preserves the antioxidan ts and nutrients.

Expeller pressed. This method also uses grinding and pressing, but with extreme amounts of pressure, sometimes up to 15 tons per square inch. This intense amount of pressure creates a lot of heat and friction that takes the oil to temperatur es of up to 300 degrees Fahrenheit .

Solvent extraction . This technique uses chemicals, such as hexane, to remove oil from olives. The oil is then boiled to get rid of the chemicals. The oil may then undergo additional heat processing , bleaching, or deodorizin g, which leads to a bland oil, but one with a high smoke point and long shelf life.

Steps to olive oil making once you've grown and picked the olives:

1. Cleaning the olives: Stems, twigs and leaves are removed and the olives may or may not be cleaned with water to remove pesticides , dirt, etc.

2. Grinding the olives to paste: Stone rollers or wheels roll in circles on a slab of granite to grind the olives into a paste, or an electric motor attached to a toothed grinder pulverizes the olives as they are flung away from the center.

3. Mixing to increase olive oil yield: Mixing or Malaxation for 20 to 40 minutes allows small oil droplets to combine into bigger ones which can be removed in the next step. It is an absolutely necessary step. The paste is often heated to 28 degrees centigrade during this process.

4. Separating the oil and water from the fruit (pomace): using a press.

5. Separating the oil from the water: the liquid is spun by a centrifuge .

6. Processing the oil, further extraction : refining, bleeching and deodorisin g, to reduce acidity and improve flavor.

7. Storage and Bottling considerat ions: Olive Oil can be stored in containers as mundane as plastic or as indestruct ible as stainless steel. Oil deteriorat es through the action of lipase and other enzymes in the oil and the action of oxygen. Oxidation or rancidity speeds up with light and heat exposure.

8. Tasting and rating the oil: Olive oil is graded by its acidity and also by its flavor as judged by experts.

Categories

1) Extra virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 1 gram per 100 grams

2) Virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 2 grams per 100 grams

3) Ordinary virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 3,3 grams per 100 grams

In Crete nowadays modern equipment is being used to produce olive oil. Here you find some pictures of the older machinery.

Old olive mill.png

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How Olive Oil Is Made