What is cold pressing?
The trade of olive oil has evolved over centuries and there so many terms, phrases and expressions. Some of these terms are now obsolete while some are still used by manufacturers and traders. Some of these terms are now official and must used in accordance to the official rules and regulations. Examples of such official names are extra virgin, olive pomace, refined olive oil etc. There are others which are not recognized by any official body like IOOC or USDA and are just used by traders on their labels to show the quality. Cold pressed, first press, single estate etc are some such terms which are unregulated and do not have any official backing.
“Cold pressed olive oil refers to oil made from olives crushed with a traditional stone mill or using a continuous hydraulic press. No heat or chemicals are administered to extend or alter the oil.”
Knickerbocker, Peggy; Olive Oil From Tree to Table, Chronicle Books, Sans Francisco, California, USA.
All olive oil was originally pressed without any heat. It is a process when oil is extracted without the use of high temperature and without any chemical changes to the oil. In old times this was the only method used for production. Oil produced under this method is normally the best grade and contains low acidity, high micro nutrients, aromatic flavor and perfect color. This is also, sometimes, labelled as first press which means oil obtained when the olive fruit is pressed the first time. The second pressing is referred to the paste after the first press which is mixed with hot water or steam and another press is applied to extract the remaining oil from the pulp. The lower quality obtained from the paste through heating and chemical process is referred to as olive pomace oil.
Is the old cold pressed way healthier?
There is not doubt that if strict hygiene conditions are met, then this is the best oil produced. It has unparalleled taste, aromatic flavor and rich in healthy components. It is, however, difficult to maintain strict hygiene control and the oil may get contaminated easily. In the so called small-village or family-stone mills, the cold press is conducted by people and animals such as donkeys and oxen. It has been observed that these people do not care much about the standard health and hygiene requirements and hence fail to meet the health and cleaning standards. It is also not easy to clean the traditional pressing mates completely and satisfactorily. These mates are made from dry grass and if not cleaned properly may develop organisms due to fermentation. Cold pressed oil qualifies for the official grade of being extra virgin if it meets all other standard criteria as specified by IOOC.
Are there any modern methods of Cold Pressing?
Modern industry produces a huge amount of oil and it is not possible to meet the demand by adopting the old methods. New technology makes the mass production possible and yet maintains the quality if all the standards are adhered to. According to oil producing experts, the olive paste is always warmed but not beyond 27C or room temperature. Although, the modern extraction methods uses machines such as centrifuges and decanters, the process is only mechanical and does not involve any overheating or chemical processing. According to IOOC standards and regulations this is still eligible to be called as cold pressed.
What happens to the paste after the Oil is Cold Pressed?
In old days they would mix water with and then heat it and press again to get the residual oil. In modern days, the remaining pomace is sold to the oil refineries. They use high heat, steam and solvents to remove any residual oil. This is a chemical process and it alters the quality of the oil. This is oil is called olive pomace oil.
Modern VS Old Methods, Which One is Better?
1. Traditional methods does not apply any heat at all other than heat produced by pressing. While in modern methods it is allowed to be up to 27C.
2. In old tradition method, the paste is crushed by a millstone where the stone is rolled over the olives using a big lever turning to keep the stone rolling. The lever is either operated by people, donkeys or oxen. In modern methods, the paste is made by crushing the olives in a machine.
3. In old method, the paste is spread over several mats layered upon each other and then pressed using the level mechanism. In the modern method, the horizontal centrifuge separates the juice from the pulp, while the vertical machine separates water from the oil.
4. Quality and flavor of the old method is higher than the modern method. However, it is difficult to carry out the process under required hygienic conditions. There is a greater risk of contamination. In modern mills, there is little risk of any oil contaminated due to low hygiene levels.
It would be really difficult, if not impossible, to produce all oil oil using the old aged and traditional methods. This is because the demand for the oil is very high and commercial production in large quantities is not possible without the use of modern technology. The advocates of modern machines methods claims that modern centrifuging is quicker, faster and more hygienic and so healthier. In some countries, such as Tunisia, some small commercial growers still stick to the old gold methods by replacing their oxen and donkeys with electrical power.
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