Olive Oil - from tree to table.

Olive oil is an oil obtained from the olive (Olea europaea; family Oleaceae), a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps. Olive oil is used throughout the world, but especially in the Mediterranean countries.

Over 750 million olive trees are cultivated worldwide, 95% of which are in the Mediterranean region. World olive oil production in 2006-2007 was 2.8 million tonnes. 

Olive oil has been a staple food in the Mediterranean for thousands of years. The process for making olive oil is relatively simple, especially as it is practised in rural areas of Italy. Commercial olive processing is somewhat more complex, but it still relies on the same basic principle: crushing the olives to release the oil trapped inside. 

The olive harvest is the first step in making olive oil. Traditionally, olive trees were beaten by hand to release the fruit, although many processors use commercial machinery today to strip the trees.

Once the olives have been picked, the clock starts ticking: they must be brought to an olive mill as soon as possible, or the acidity level will climb too high, ultimately affecting the flavour. 

Olive oil is produced by grinding olives and extracting the oil by mechanical means. Green olives usually produce more bitter oil. For good quality extra virgin olive oil care is taken to make sure the olives are perfectly ripened. The process is generally as follows:

• The olives are picked through to remove large branches and leaves, and then sent through a cleaner which removes dirt, leaves, and twigs, leaving plain olives behind.
• The olives are ground into paste using large millstones (traditional method) or steel drums (modern method).
• If ground with mill stones, the olive paste generally stays under the stones for 30 to 40 minutes. A shorter grinding process may result in a more raw paste that produces less oil and has a less ripe taste; a longer process may increase oxidation of the paste and reduce the flavour. After grinding, the olive paste is spread on fibre disks, which are stacked on top of each other in a column, then placed into the press. Pressure is then applied onto the column to separate the liquid from the paste. This liquid still contains a significant amount of water. To split the oil from the water the process of centrifugation has been developed. The centrifuges have one exit for the (heavier) watery part and one for the oil. 
• In modern production units steel drums are used in the grinding process , which takes about 20 minutes. After grinding, the paste is stirred slowly for another 20 to 30 minutes in a particular container (malaxation), where the microscopic oil drops unite into bigger drops, which facilitates the mechanical extraction. The paste is then pressed and the water is separated from the oil by centrifugation as described before. 

The resulting olive oil is called virgin, because it is made through a purely mechanical technique. Olive oil with acid levels measured at less than 1% is considered “extra virgin” and usually has a particularly rich and intense flavour. Olive oil with a higher acid level (1-3%) is labelled “virgin.”

First cold pressed means "that the fruit of the olive was crushed exactly one time-i.e., the first press. The cold refers to the temperature range of the fruit at the time it is crushed." In Italy the olives are collected in October and November. 

Olive oil contains a group of related natural products with potent antioxidant properties that give extra-virgin unprocessed olive oil its bitter and pungent taste. Evidence from epidemiological studies suggests that a higher proportion of mono unsaturated fats in the diet are linked with a reduction in the risk of coronary heart disease. This is significant because olive oil is considerably rich in mono unsaturated fats, most notably oleic acid.

There is a large body of clinical data to show that consumption of olive oil can provide heart health benefits such as favourable effects on cholesterol regulation, and that it exerts anti-inflammatory, anti-thrombotic, and anti-hypertensive effects both in animals and in humans. 

As they are the least processed forms of olive oil, extra virgin or virgin olive oil have more monounsaturated fatty acids than other olive oil. These types also contain more polyphenols, leading to a healthier heart and lower "bad" cholesterol.

Olive oil is the main cooking oil in countries surrounding the Mediterranean Sea. Extra virgin olive oil is mostly used as a salad dressing and as an ingredient in salad dressings. It is also used with foods to be eaten cold. 

Choosing a cold-pressed olive oil can be similar to selecting a wine. The flavour of these oils varies considerably and particular oil may be more suited for a particular dish. Also, people who like lots of tannins in their red wines might prefer more bitter olive oils.

An important issue often not realized in countries that do not produce olive oil is that the freshness makes a big difference. In time, oils deteriorate and become stale. One-year old oil may be still pleasant to the taste, but it is surely less fragrant than fresh oil. After the first year, olive oil should be used for cooking, not for foods to be eaten cold, like salads.

The taste of the olive oil is influenced not only by the soil on which the olive trees grow, but also by the time when the olives are harvested and ground.

To prevent alteration in colour, taste, and odour, the oil should be kept away from light, ideally in a dark glass bottle, and stored in a cool place. Never refrigerate or freeze. 

Sit back, eat and enjoy!