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What is an oil mill and how does it work? Complete guide
For those of us who live in Andalusia, especially in Cordoba and Jaen, the word oil mill is part of our everyday vocabulary. Since we were children we visited these places accompanying our parents to empty the trailers after having spent all day picking olives. If you want to know more about olive oil mills, read on!
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What is an olive oil mill
The main activity of an oil mill and for which it is mainly recognized is the production of olive oil. In fact, its name comes from the Arabic al-maʿṣara (المعصرة) which mainly means “place where it is squeezed”. Hence we often use the term olive juice since the oil is extracted by mechanical means.
Another term very used to name the oil mills is “mill” since really to be able to obtain the oil it is necessary to grind it, to this process we call it milling.
In Aceites la Muralla, besides producing extra virgin olive oil, we also package and personalize it so that our customers can enjoy the EVOO that we produce with so much affection.
History of oil mills
The oil production process as we know it today is very different from the way our ancestors extracted oil. There was still no such professionalized machinery as we have today, so the only means that existed to operate the mills were animals such as donkeys or mules. For the traditional milling procedure, stone mills made of granite with conical millstones were used, which crushed the olives at the base of the mill. The paste obtained was then passed to a press, where the oil was extracted.
In ancient times, the press was fundamental to extract the oil, using a lever, where the material to be pressed was placed between the counterweight and the shaft. This gave rise to the “beam press”, a common device until the 19th century. Later, the “screw press” and the “arbor press” replaced the beam press. The screw presses, more compact and easier to use, required only one operator and reduced the risk of breakage.
For the initial separation of the oil in the old mills, the liquid extracted from the olives was poured into interconnected pools located at lower levels of the building. A filter at the entrance of the ponds retained the solid residues. After the first extraction, water was added to wash the oil and promote its separation from the solid components. In these tanks, the oil separated naturally from the water, remaining in the upper part, while the "alpechín" (dark liquid part) was deposited at the bottom.
After the oil was decanted, it was collected in jars and washed two or three more times. The final oil was bottled, and the remaining residue was used to make soap and, later, to feed livestock.
Parts that make up an oil mill
An olive mill is composed of several parts:
- Yard: normally olive mills have a large yard where the large vehicles needed to transport the olives such as tractors and trucks can maneuver quietly.
- Hoppers area: the hoppers are where the olives are poured and are used to weigh and classify them according to their quality and variety.
- Factory: this is the place where the oil is produced, usually a large room with the large machines necessary to produce the oil.
- Cellar: once the oil is produced, it is necessary to store it correctly depending on its quality and variety. For this it is necessary to have a room with large tanks.
- Bottling machine: once we have the oil produced, filtered and perfectly stored, it is time to bottle it, to dose that great quantity of liters in the suitable formats so that the final consumer can acquire it.
Thus ends this long process in which we go from harvesting the fruit to obtaining our precious EVOO.
Operation and production process
The olive production process consists of:
- Harvesting: the first step logically is the harvesting of the olive the farmers spend the whole year taking care of their olive grove so that when the end of October arrives approximately they can harvest their fruits. Once harvested, the olives are brought to the mill to produce the oil.
- Cleaning: The olives are poured into the hoppers where they are weighed and then passed to the washing machine where they are cleaned to remove leaves, dirt and other impurities.
- Grinding: The olives are ground, breaking both the fruit and the stone, to obtain a homogeneous paste.
- Beating the paste: This paste is slowly beaten or kneaded to facilitate the separation of the oil. During this process, the oil droplets clump together to facilitate extraction.
- Oil separation: Centrifugation is used to separate the oil from the water and solids at a higher speed and continuously.
- Decanting and filtering: In this stage, water and other impurities are removed to obtain pure oil.
Cualidades del AOVE de almazara
If something characterizes our oil mills is the quality of the Extra Virgin Olive Oil we produce, far from a systematized production more typical of large cooperatives in the oil mills we make smaller productions always controlled by our oil mill master who is in charge of monitoring all the parameters and indicators for our EVOO to be exceptional. Values such as the temperature at which it is extracted, the time that passes from the time the olive is harvested until it is milled are very important in the final result.
In Aceites la Muralla we are proud to have our master miller who has over 30 years of experience and is undoubtedly one of the most responsible for the quality that characterizes us. If you want to know his story we leave you the link to this blog.