Manufacture: The oil mill
The next step is in the oil mill. The following applies: The faster an olive oil is extracted, the less external factors influence the product in a negative way – and the better the coveted "extra native olive oil" tastes with its impressive aromas. Thousands of years ago, we knew about the differences between olive oils and their production. If the olives are crushed – as in antiquity – in the handstone press or in the hand mortar, the oil is exposed to oxygen and the leaking amniotic fluid for too long. This initiates an oxidation process that quickly makes the oil rancid.
The stone press is the forerunner of another and more sensible system: "Canalis et Solea" (rinne and platform). A prototype of this press stands in front of the facade of the temple Medinet Habu in Luxor/Thebes, which Ramses III had built in 1153 BC. It shows a carefully worked flat stone with an annular recess and drain inge. One can assume that in the middle stood a basket of crushed olives, from which oil and amniotic fluid were squeezed out with a weight or by crushing with wooden sandals and drained over the gutter into the lower vessel. Although the Egyptians were able to process a larger amount of oil in this way, it was exposed to oxygen for too long.
The grinding system "Mola Olearia" (oil mill) made considerable progress: it was in use from the 3rd century BC and was considered a sensation at that time: for the first time, the grinding process was mechanized by a continuous course of motion. Thus, on a large, rounded ground stone carved from a single stone block, a roller or wheel-shaped grinding stone rotates around a vertical central axis. The horizontal axis can be adjusted in height. This was important even then, because they did not want to crush the olive kernels with them, because, according to the Roman agricultural experts, they would worsen the taste of the oil. Today it is common to grind the seeds with them, as they provide a desired tart aroma.
The "Mola Olearia" is the original form of the mill system, which is still in use today, with up to five grinding wheels turning on a round stone table. The grinding stones were driven by horses, mules, camels, donkeys, but also by people who led the drawbar around the grinding table.
The ancient mills were used throughout the Mediterranean. Due to the high acquisition costs for modern plants, the nostalgic device is still in use in countless villages, especially in North Africa and Asia Minor.
While in the type "Canalis et Solea" the crushing of the olives and the pressing of the olive breis only with this one tool happens, after the grinding of the olives in the "Mola Olearia" follows a second separate operation: the pressing of the pulp in the "torculum", the oil press. Here, too, a wide variety of variants emerged over time.
One of the prototypes par excellence is the press with the press bar, which compresses the press mats stacked over a stone table, filled with the olive pulp, with large stone weights increasing the pressure.
Another type is the screw press. The pressure on the press mats is exerted by means of a large wooden screw. A system that is still used worldwide today. Only the materials have changed: instead of wood, you take metal. If the pressure was first generated by muscle power and then by steam power and hydraulics, the electricity later took over this task