In all systems, the leaking oil-water mixture is collected in large vessels. The heavier water settles downwards and the lighter oil floating up can be extracted. These oils usually remain unfiltered. But because they too have been exposed to oxygen for too long, they age quickly.
Today's modern grinding operation is as effective as it is unromantic: the oil mill, with its centrifuges, hoses and filling lines, is more reminiscent of machine rooms. First the olives are freed from leaves and branches with a suction system, then washed and led via an ascending conveyor belt into a huge steel grinding head, reminiscent of the grinding system of our pepper mills. The resulting olive pulp then enters a stirring machine, which serves to hold the porridge from oil, water and marc together. This agitator is almost airtight to keep the oxygen away. From there, the olive pulp is fed into a centrifuge, where it is divided back into water, oil and marc. The oil flows into a second centrifuge to remove the last traces of water. The fine proportions of pulp still contained in the oil can be removed by various filter systems. The whole thing takes 30 to 40 minutes. According to the EU Oil Regulation, 27 degrees Celsius for "extra-native olive oil" must not be exceeded. The oil is stored in dark and cool cisterns and tanks made of stainless steel, ceramic or glass. By indenting nitrogen into the upper area, contact between oil and oxygen is prevented and thus early aging.
The amniotic fluid is fed into large reservoirs. From there, it is brought directly back to the olive groves as a valuable fertiliser, because it contains minerals and vitamins.
If it stays in the basins for too long, it spoils and must no longer be used for fertilisation. It must be disposed of. If a last remaining oil is pressed from the marc, it must be chemically processed and sold as "marc oil".