Legend has it that the first olive tree grew on Adam's tomb. We all remember the olive branch that the dove brought to Noah, signaling the end of the flood. When the city of Athens was founded, so goes the legend, a heated argument broke out in Olympus. Pallas Athene, goddess of wisdom, and Poseidon, god of the sea, both claimed the new city for their own. Zeus, Father of the Gods, gave his judgment: whichever of the two could create something entirely new, and most useful to humankind, should be the city's honored patron. Poseidon struck the ground with his trident and up sprung a horse. Athene smiled, struck the ground with her wand, and out sprouted an olive tree. Zeus awarded Athene the city, which was named in her honor, and today is the capitol of Greece. Who could question which of the two was to be of the greatest service to man?
Civilizations have flourished using olive oil as a cooking staple, as an offering to the gods, for cosmetics, fuel, and as a medicine. Homer first elevated the status of olive oil by renaming it "liquid gold" and Hippocrates described it as the "great therapeutic". The olive tree is the tree of all holy books. The Bible includes 140 references to olive oil. Olive trees still stand today in the Garden of Gethsemane on the slopes of the Mount of Olives. To Christians, the olives on these trees symbolize Christ's tears. Olive oil is used in the Roman Catholic Church at baptism, confirmation, ordination, and in the sacrament of the last rites. The miracle that caused a tiny amount of olive oil to last through the siege of the temple of Jerusalem is remembered each year in the celebration of Hanukkah. It is said that the holy transit of olive oil, wine, and bread has been integral to the region's history, lore, and religious rites. The Koran says the olive tree comes from Mount Sinai. There, olive oil is obtained from its fruit, and this oil is used to enhance the flavor of food. Olive oil was used to crown victorious athletes and anoint monarchs -- and not coincidentally -- is generally referred to as the "King" of vegetable oils. In fact, in the Book of Judges, the trees voted to elect a monarch to rule over them, so they chose the olive tree, who refused: "give up my oil by which gods and men are honored, to go sway over the other trees?"
Olive oil was exchanged as a gift to signify fertility, friendship, purity, and strength... the most enduring legend tells of Noah's dove, returning to the ark, carrying an olive branch, as a sign of prosperity, and peace. People are grateful for the sacred gift that provides not only fuel and light, but also food (olive oil/olives). Olive oil has been the cornerstone of the Mediterranean diet for thousands of years. Along with wheat and grapes for wine, olive oil forms the triumvate, the holy trinity, as it were, of Mediterranean cooking and culture. It has symbolized longevity, fertility, maturity, and peace in various cultures. Will olestra still be on the menu in the year 2010? In fact, in countries where the olive tree is pre-eminent, one of the cruelest things to say about someone is that they are the kind of person who would cut down an olive tree.
The future of olive oil is today secure, as it was one of the first forms of life to be planted on the moon.
The long, rich tradition of the olive tree, which Sophocles described as "the tree that stands unequaled," is woven through the tapestry of human history...the olive tree dates back to 3500 BC, and archaeological discoveries show that the olive has been used since 6000 BC... a history of almost 8000 years. The oldest known record of olive oil is on earthenware tablets from 2500 BC, from the island of Crete, in the reign of King Minos. The olive crop area is estimated to be some 9.8 million hectares, with approximately 1.2 billion olive trees.
The three great Abrahamic faiths - all rooted in lands where olive trees grow - pay heed to the trees' gifts: it's no accident that olives provide the chrism, or consecrated oil, used in Greek and Latin churches for baptisms and ordinations. Or that the miracle celebrated at Hanukkah commemorates a spontaneously replenished supply of olive oil in the lamps that lit the Temple of Jerusalem. Here is the tree again, in the Koran: "A sacred tree..[whose] oil almost gives light of itself though no fire touches it."
Today, the olive tree has spread far afield - to North and South America, Australia and New Zealand, India and China. But wherever is split trunk rises and its knobby, twisted branches and silvery leaves case shade, the olive tree remains a beloved and quintessential symbol of the Mediterranean, its historic home.
The wild olive tree (oleaster) still grows in most of the Mediterranean countries, but bears little fruit. The domesticated tree belongs to the family of olea europaea, flowering plants of which jasmine and lilac are also members. There are hundreds of varieties of olives, and like the grape, results depend on the climate/soil, - whether the olives will be pressed for oil, or used in eating.
The culture of olive trees requires the patience of generations of agriculturists. The olive tree is green, and non-deciduous, with a gray trunk that comes to appear wrinkled and knotty. An olive tree takes twenty (20) years to mature, however, it begins to give fruit five (5) years after planting. The olive tree is an evergreen tree, and stands anywhere from 10-50 feet high. An average tree will yield about 22 pounds of olives during harvest (enough for 65 liters of oil). After 100-150 years, its production declines, which influences the quantity, not the quality, produced.
Olive tree leaves live for about three years, before dying to make way for new leaves. Olive leaves are paired opposite each other down the branches. They are single and undivided, rather like a willow leaf, lance-shaped, shiny, and leathery. The upper surface is dark green, and the lower surface appears to be silvery-green, because it is covered with minute scales. This is why, in the wind, olive trees seem to shimmer in a silvery haze. Orchards operate on a 2-year cycle, with a good crop following a poor one. Some olive varieties are cultivated specifically to produce oil. Oil producing olives are typically smaller in size, with a higher fat content than the larger, lighter-skinned fruit olive.
An olive tree blooms in late spring, with clusters of white flowers. Depending on the variety, there can be anything from ten to over forty flowers in a cluster, but only one in every twenty flowers will become an olive. Even though olive trees are self-pollinating (wind), it is very difficult for the flowers to achieve fertilization at the best of times. Weather is the prime enemy, though the tree remains hardy to 16º F, the fruit to 26ºF. As a result, fruit setting is erratic, but it is improved by planting another variety of olive tree, for cross-pollination.
The terrain should be hilly...the tree grows best at 1-2000 feet above sea level, in lime soil. The trees are small, with deep roots, thirsty, with small olives and pits, and a high content of oil particles. In early autumn and spring, the soil in the groves is plowed and weeded, and the trees pruned. Pruning is most important, but is labor intensive. You must thin the growth on the crown of the tree, so the fruit-bearing branches can be exposed to the sun and air. Too, the removal of branches means that the nutrients in the soil will be better utilized.
There is no part of this eternal tree which a person cannot utilize. Olive wood, for example, is highly regarded for its beautiful black and brown grain, and its honey color. Remarkably, the leaves of the olive tree have always been regarded as curative -- when in water, and taken as an infusion. Even the residue of stones and skins may be used in many mills as fuel, and fertilizer.
Olive trees are generous -- they do not die of neglect, need little water, and produce for decades. However, it is now known, that the olive tree grows best when it is correctly watered, and grown in rock-free, fertile soil, on appropriate terrain.
Some olive trees live to be more than 2000 years old, many are 400-500 years old, but most average 200 years in age. There are approximately 6.9 million holdings that grow olives, and the average size orchard is 1.42 hectares. In the European Union, it is estimated there are 2.45 million holdings with an average orchard size of 2.2 hectares.
"Except for the vine," said the Latin author Pliny (AD 23-79), "there is no plant which bears a fruit of as great importance, as the olive." The olive (olea europaea) grows on a tree, native to the Eastern Mediterranean, the very symbol of Mediterranean culture. Jasmine, lilac, oleander, and privet are all part of the Oleaceae family, but only olia europaea is cultivated for the fruit.
The olive is a drupe, a fleshy fruit with a single hard stone (peaches, plums, and cherries are drupes). There are hundreds of varieties of olives (the fifth major oil producing areas of Spain alone have almost 60 different types of olive trees, in Italy 30 types).
Green olives are harvested from August-November. Ripe olives are harvested from November-March. Less ripe olives give oils that are greener, more bitter, and have a slight zing of piquancy.
In our pursuit to find the best olive oil, we must not forget that the fruit itself offers a myriad of tastes when preserved whole. There are delectable ranges of table olives: green or black, small or hard, large and fleshy, pitted or stuffed, packed in brine or oil -- the variety is enormous.
When the olive first starts to form on the tree, it contains no oil, only a mixture of organic acids and sugars. By the magic of nature, a transformation gradually occurs, as the olive ripens. A chemical process, called lipogenesis, slowly turns the acids' sugars into oil, as the olive turns from pale green, eventually to black. Olives can be picked at any stage through the process, and the degree of ripeness will determine its taste.
By the end of May, the modest flower of the olive tree becomes a tiny berry, which by September has grown into a full-sized olive. Olives do not become fully ripe until winter, but different varieties are picked at different degrees of ripeness, and this determines the taste. Between June and October, fruition takes place. This is the time during which the stone (endocarp) hardens, and the pulp (mesocarp) fills out. The flesh is encased by the skin (epicarp), and as the olive ripens, the epicarp changes from green to violet, from red to black. Six to eight months after the blossoms appear, the olives have maximum oil content -- they are black, and fully ripe.
Harvesting usually begins in September, and can run as late as March, although most are picked by December. Olives picked green produce little oil, and are very firm and tangy. As olives ripen they yield more oil, but this oil tends to be less fruity. If olives are harvested too "green", it can result in "peppery" oil.
Watering the trees leads to larger olives with greater oil yield, but it also produces a less flavorful oil. Like all fruit trees, the olive, besides the problems of weather, is subject to attack from fungi and insects. The olive's particular enemy is the olive moth, whose caterpillars will happily eat their way through leaves, and buds. Some producers may spray with pesticides, while others choose to grow their olives organically, because of concern over contamination of the fruit by pesticides.
You can taste a difference between green and black olives...you may like one better than the other. Green olives have very little oil, their flesh is firm because they are not yet ripe, and they have a sharp tang. Black olives are full of oil, the flesh is soft, and the tastes mellow -- because they are ripe. Green olives, because they are unripe, are inedible, unless treated to remove their bitter glycosides. Treatment is done on a commercial basis by immersing the olives in a soda solution, then washing them thoroughly in clean water, and finally packing them in brine. Green olives are used in chicken and rabbit dishes. Black olives, in contrast, being fully ripe, only need washing, and preserving in brine, or dry salt. Black olives are added to pasta dishes (as Puttanesca) and fish dishes. With table olives, the firmness and flesh of the fruit is important, whereas olives for pressing are prized for their high oil content.
Some growers still preserve their own olives, and chili pepper, garlic, oregano, or wild fennel can flavor the brine. A specialty of Umbria is black olives flavored with orange rind, garlic, and bay leaves. Sicilians stuff their olives with anchovies and capers.
It takes some 1300-2000 olives to make just one quart of olive oil, or 24 pounds of paste to produce 34 ounces of oil by partial extraction; 600 trees produce two tons of olives, which make 100 gallons of olive oil (6 trees / 1 gallon). Oil makes up 15-26% of the ripe fruit, depending on climate, condition, and care in cultivation. Present systems enable suppliers now to realize, on an average, a yield of 90% of the oil contained in the olive. Throughout the world, there are approximately 9.8 million hectares with over 1.2 billion olive trees that are farmed either intensively/extensively, of which 98% are located in the Mediterranean countries. Trees bear on a 2-year cycle. Typically, a plentiful crop of olives one year is followed by a dearth the next.
It is estimated that the olive product sector generates 200,000,000 working days yearly, the majority of which are jobs for people of limited incomes. Where international trade is concerned, the volumes traded on world markets amount to approximately 480,000 metric tons of oil and 250,000 metric tons of table olives. Today, 93% of all olives are harvested for their oil, the remainder for the table. The EU/Tunisia were the world's top producers of olive oil (76% / 8%).
Like all agricultural products, the cycle of olive oil production begins with the harvesting of the olives from the tree, and ends with the storage, and eventual distribution of the oil.
Similarly, the characteristics of the oil obtained in this process are conditioned by:
- The varieties of the olives and the climate of the area where they are grown. The same varieties may produce different oils even in the same area, if there are differences in climate;
- The components, and tilth of the soil;
- The systems of cultivation that regulate the amount of water, either by rain or irrigation, that reaches the roots and is retained in the soil;
- Any blights or destructive pests that can hinder the development of the olive or damage the fruit.
Thanks to an attic amphora of the 6th century BC (British Museum / London), we know how olives were harvested. The drawing shows four peasants: two people, standing, strike the branches with long poles; the third perched on the treetop, shakes the crown; the fourth scoops up the fallen olives into a basket.
The harvest (picking) can start in September, and may go on until March, depending on the country, and whether the olives are being picked green or black, for eating, or for oil. Generally, olives harvested early are the most flavorful/richest/spiciest, and those harvested ripe are milder in taste. Unlike wine, olive oil is at its best, when fresh. In the course of the harvest, the pickers will go back to a tree, time and time again, to gather olives at the best stage of ripeness. Since the olives are fragile, and firmly attached to the tree, they are still frequently harvested by hand, or with poles that have wood or plastic comb heads. Workers balance on ladders, climb into the branches, snatch limbs with one hand, and comb with the other. The falling fruit is collected in nets, and lay out underneath the trees. Some growers use tractors with claws that grasp the trunk of the tree, and shake the fruit down -- but this process leads to damage. However, with mechanical assistance, the daily harvest per picker triples. The machines knock down 80% of the olives, and the remainder comes by hand/poles...using the latter method, a worker can pick from 1000-1700 pounds of olives a day. The greatest impediment to the mechanization of the olive harvest is that so many of the groves cling to the terraced sides of mountainous terrain, with access so steep, that no tractor can pass. 60% of the final crops cost is picking labor.
In the collection phase, canvasses, nets, or polyethylene covers catch the fruit, and prevent it from touching the ground. Olives shook loose (De Vuelo) are considered better than the overripe ones that fall by themselves (Du Suelo). Wet olives ferment faster and fermentation can ruin an oils flavor. The collected harvest is gathered into straw baskets, and often picked over to clean out leaves, twigs, and unsound olives. The olives are loaded into a waiting trailer. The olives are taken to a mill. The farmer's load is weighed and provided a receipt -- to collect the oil when his olives have been pressed, or when the mill sells his olives/oil to a large company. If the oil is to qualify as "virgin," Spanish law forbids the olives be stored more than 72 hours, between harvesting and pressing.
When the olives are removed from the field, they are bathed in cold water. Oil, which makes up 15-26% of the olive, is contained in pockets within the fruit's cells. The crushing process breaks these cells, releasing all the oil from the olives. Modern mills have computers that weigh, sort, and wash the incoming harvest. The grinding begins when the olives are crushed, with their stones (pits) in, though, in some places today, the stones are removed first. Olive picking is not overly tricky, but it is physically tiring. You need patience, skill, and stamina - and no autumn gales.
Most oils on the market are highly processed, and nutrient-deficient. When refining conventional oils, seeds are cleaned and cooked, the oil extracted by solvents, degummed, refined, bleached, and deodorized. Olive oil is the juice of the olive fruit -- unrefined, and minimally processed. Olive oils are the only unrefined oils sold on the mass market.
The basic principals of milling are the same today, as they were long ago. The simple process is you crush the whole olive, pit and all, separate the liquids from the solids, then separate the water from the oil. Originally, the olives were crushed underfoot, much like grapes (The Romans depict the wooden level press as early as 300 BC). However, the Roman screw press was the real breakthrough -- the fruit was crushed between two stone plates, drawn together by the action of the screw, which allowed maximum oil to be extracted. Ancient oil mills used circular stone vats, where a huge vertical circular millstone, fixed at the center by a wooden shaft, was drawn round by mules/slaves/women (followed by steam/gas, then finally electrical engines), crushing the olives in stone mortars, linked by a horizontal shaft, or four cone-shaped rollers, set at right angles.
In some small farms and villages, the traditional mills are still in use -- olive mills are called Almazara in Spain, Moulin in France, and Olificio in Italy. Where the old has made way for the new, these original millstones now adorn many of the entrances of the estates, like faithful old retainers.
The production of olive oil is primarily the separation of the liquids contained in the olive, from the solid components of the fruit, followed by the separation of the oil from the olive's naturally held water. There are three types of processing:
The first is the screw press, invented by the Romans 2000 years ago, and still used.
The second is the traditional press, (hydraulic / discontinuous) in which the washed fruit is first crushed in hammer mills. The mill is actually a series of metallic hammers that crush or cut the olives with a series of parallel knives. You begin with whole, clean fruit, harvested at the moment of optimum ripeness. Then, a paste is made by crushing the whole fruit. The fruit is crushed under granite or steel millstones... this process opens the olive's cells that hold the oil. The resulting paste (looks like a tapenade) is then spread onto loosely woven hemp mats, or synthetic fabric pressing bags, with a hole in the middle. The mats/bags are stacked, up to fifty at a time, interspersed with metal discs between pressing plates, on the vertical spindle of an expeller, or hydraulic press. The mats allow the oil to drain through, while holding back more solid matter. 300-400 tons of pressure are applied downwards. Olive oil is less dense that water, so the oil rises to the surface, where it can be decanted off. The olive paste is then further cut and mixed in order to obtain a better separation of oil/water. From time immemorial, this separation has been performed by the natural decantation of the liquids.
The third type of processing to separate the oil from the paste is by means of centrifugation, which means the paste is spun round at high speed. In this continuous process, the olives are crushed in the traditional press, but then water is added and separated in horizontal centrifuges, then further separated in vertical centrifuges. The continuous system, by centrifuge, can use recycled vegetable water vs added water. Centrifuging can drive off the greater part of the free-fatty acids, and the oil then can be treated in the vacuum to remove the rest. There are many intermediate methods, like the sinolea process, which involves spinning fine blades. The continuous system presents advantages as: higher production capacity, avoiding the storage of olives, and better cleanliness, hygiene, and yield. Too, the continuous system, with water vegetation provides higher quantities of polythenols in the oil, which are natural protectors against oxidation.
Regardless of the means of mechanical extraction (expeller/hydraulic, centrifugal/pressure), the oil is then decanted, filtered, and allowed to settle, after pressing. Quality evaluation of the oil is done by mill technicians, who taste the oil and measure its acidity. In a certain sense, olive oil is handled much in the same way as fine wine. The mill technicians separate the oil to be stored, and just before bottling, analyze the oil to test for possible defects in the oil that could be caused by oxidation during storage. The oil may be filtered, or be sold as unfiltered. It takes about 5 kilos of olives to make 1 liter of oil.
Extra virgin olive oil has a distinct richness and depth of flavor. It is produced naturally, simply filtered without additives or chemicals, has a full taste, fruity aroma, and pressed at a low temperature, between 25-28º C (a process that preserves the full flavor and nutritional components of the oil). In the Mediterranean, to qualify for the label "Extra Virgin", an olive oil must conform to 4 criteria:
- Only washed/filtered, not subject to any chemical process;
- Must be cold pressed at a temperature of 25-28 degrees C, 24-48 hours after picking;
- Exhibit an acidity level of less than 1%;
- Have a perfect aroma/flavor/texture and no olfactory defects.
This set of criteria has been established by the International Olive Oil Council (IOOC) in Madrid.
Virgin olive oil has a sharper taste, and contains an acid level of 1-2%. These oils are typically cloudy, and have an extremely strong, peppery flavor for several months, where they are allowed to settle in cool cellars. If filtration is desired, the oil passes through cotton before bottling. However, if you notice that your oil is cloudy, with bits of sediment floating around on the bottom of the bottle, this is a natural part of the oil-producing process.
Olive oil that does not meet the exacting standards of extra-virgin or virgin oil, along with the pulp or "inferno" that remains after the initial pressing, is further processed -- to neutralize acidity, and remove any off-flavors. Refining consists of concurrent processes of decolorization, deodorization, and neutralization -- the oil is filtered through carefully prepared earth, which removes the chromatic pigments that gave them intense color. The oil is then deodorized in vacuum at high temperature, while being sprayed with water -- which rids the oil of any strange odor. The resulting oil is without color, taste or aroma.
Olive oil marketed as "refined" olive oil, may be blended with extra virgin olive oil to enhance flavor and improve color -- and is typically sold as "pure" olive oil. The words "pure" or "100%" on a label merely indicate that the oil has been refined of impurities, and not processed from any other source than olives.they are not indicators of quality. Pure oils have a nutritive value equal to finer oils, but may actually be a blend of virgin, and refined oil.
Extra Light olive oil has the same acidity as pure. The olive oil is lighter in color, more delicate in flavor than pure, due to less added virgin oil. Extra light olive oil is a superb oil for cooking, so not to dominate the entree flavor.
Pomace is the portion of the olive that remains after mechanical and physical operations remove the oil and water. Additional oil can be extracted from the pomace with the use of solvents. Refiners extract the oil from the olive in the identical process that US. Refiners extract oil from seeds -- as soy, and sunflower. It is possible, then, to recognize the origin of the oil, just as wine can be identified by its intrinsic organoleptic qualities, and yet it retains all the nutritional benefits of olive oil.
Cold pressed/mechanically pressed mean the same thing. In the old days, hot water was added to the olive paste to maximize oil extraction.
With modern technology, "cold pressed" is meaningless, and strictly a marketing term. Blended oils are made of selected vegetable oils, combined with extra virgin or pure olive oil -- for economical and health advantages. You can do a simple test at home to verify the product descriptions on olive oils that you purchase. Place ½ cup of olive oil in a container, refrigerate it for two days. Chemically refined oils will turn into a solid mass, while genuine extra virgin oils will create small granules of fat suspended in liquid oil.