Olive oil is the oil produced by the processing of the olive, the fruit found on olive trees. The origins of olive oil are very ancient, the first evidence of its presence was found in the area between Asia Minor and Magna Graecia. According to the processing methods and the quality of the olives, olive oil can be divided into: extra virgin olive oil, virgin olive oil, lampante olive oil, refined olive oil, olive oil composed of refined one and virgin one and different types of olive-pomace oil. The stages of oil production are different, they start from the harvest and arrive at the oil mill. Let’s see all of them, stage by stage.
Difference between olive oil and extra virgin olive oil
Extra virgin olive oil and other olive oils are obtained from the first pressing of the olives but they differ in both the organoleptic qualities and the percentage of acidity. Extra virgin olive oil is a perfect oil with an acidity that must not exceed 0.8%. So if the olives are healthy, chosen in the best ripening point and processed in the best possible way, it will most likely be an Extra-Virgin Olive Oil. For virgin oil, however, the limit is 2 grams per 100 grams. Olive oil is obtained from a mix of refined oil and virgin oil and its acidity limit is 1%.
Olive harvest: how it is done and what the methods are
The olives are harvested in the months of October, November and December according to the degree of ripeness of the olive and the harvesting traditions that change from area to area. In fact, there are those who prefer to harvest almost ripe olives, those who prefer a middle ripening degree and those who still wait for them to fall ripe on the nets positioned under the trees. One of the still frequent methods, especially in the management of familiar and non-corporate land, is that of harvesting the olives by hand or with special rakes, using bags and baskets as containers. Farmers use stairs to reach the highest points, and very often they put nets or cotton sheets under the whole perimeter of the trees to catch the falling olives. This type of harvesting just described allows a greater choice and control of the olives harvested even if the times are longer than the mechanical harvesters or the shaking machines that carry out mechanically the harvesting operation from the trees. These methods are certainly invasive and, if used badly, they can damage olive trees.
How and for how long it is possible to preserve olives
Once collected, the olives must be brought to the mill as soon as possible. We recommend that you never exceed two days of preservation to prevent the fruit from altering to the point of compromising the final result. It is preferable to store the olives in plastic boxes with holes with a capacity of max 20kg in cool and well-ventilated places without light and heat sources.
Production of olive oil in an oil mill
The oil mill is the place where the olives are processed and transformed into olive oil through various processes. The term “oil mill” derives from “milled/mill” that means to crush, to grind. Here are the different stages of the production cycle:
After the weighing operations, the olives are washed, dried and subjected to mechanical processes in the milling phase which takes place with the mill or with the hammer crusher, both machines that cause the breakdown of the cell wall and the membranes and allow the escape of the cellular juices and oil. The oil paste is thus obtained, a semi-fluid compound composed of solid parts (fragments of kernels, peels and pulp) and liquid parts (emulsion of water and oil). At this point, the next stage is malaxing in which the oil paste is stirred in the tanks of the malaxing machines and, through the movement of the internal blades, many parts of oil separate from those of the water. After 20 minutes of mixing, the pasta is ready to be inserted into the 3-phase centrifuge or decanter which allows the effective splitting of the parts, definitively separating the olive oil which is extracted from all the rest. As an alternative to the centrifuge there is the classic method of pressure extraction even if slower, more difficult to clean and more expensive compared to the continuous cycle method with centrifuge that now all modern mills have adopted. At the end of the production process the yield for each quintal of olives will be equal to a percentage varying between 10% and 20% depending on the variety, the degree of ripeness and the type of extraction. Once extracted, the oil is ready to be consumed; initially it will have a very intense color tending to green and then it will take on the characteristic golden color after a few days.
Hot or cold extraction
The difference in temperature during oil extraction involves some differences:
cold extraction has a lower yield since separation from water is more difficult, while hot extraction allows better separation of the elements and therefore a greater quantity of extracted oil. As regards the final quality, the cold method is certainly more suitable as it does not alter the chemical characteristics of the oil unlike the hot one which accelerates the oxidation processes.
How to make olive oil at home
Many people wonder how it is possible to produce olive oil at home. There are relatively small machines – compared to the standard dimensions – called mini-oil mills that allow the processing of quantities from 30kg to 50kg per hour. Otherwise there are some methods that can be reproduced at home, with easily available kitchen tools, such as the manual press.
Use of olive oil
Olive oil has several uses. It can be used cold to preserve and season food or hot in different types of cooking, such as frying. Alternatively, it is used in the cosmetics field thanks to the presence of vitamin E, vitamin A, fatty acids and beta-carotene inside.
Preparing a flavored olive oil is very simple, just leave the chosen ingredient in the oil for 15 days. Always sterilize the glass container in which to pour the mixture and make sure that the ingredients to be inserted are completely dry, to prevent mold from forming. The most popular are the oils flavored with: chilli, truffle, lemon, rosemary, basil, pistachio, bay leaf, almond, walnuts and orange but you can choose other ingredients and maybe create other creative mixes. Just be free, the kitchen is also creativity!
Benefits of extra virgin olive oil
The benefits of extra virgin olive oil are many: its antioxidant properties slow down the aging of the skin and prevent arteriosclerosis. The phytosterols inside it reduce bad cholesterol by replacing it with the good one. In addition, the different properties of olive oil allow it to protect the liver, prevent cardiovascular diseases, perform an anti-inflammatory action, stimulate the digestibility of food. In both aesthetic and food use – such as in the Mediterranean diet – extra virgin olive oil is a real panacea for the whole body.