when oil is stored. Advantages and disadvantages Proper cleaning produces higher-quality oil. Grindstones, while ancient in design, are a suitable way to grind olives, because this method breaks up the drupe's pulp while only slightly touching the nut and the skin. This reduces the release of the oil oxidation enzymes present in these organs. In addition, in this extraction method, the introduction of water is minimal when compared to the modern one, thus reducing the washing-off of the polyphenols. The exhausted paste, called pomace, has a low content of water, making it an easier residue to manage. Advantages Better grinding of the olives, reducing the release of oil oxidation enzymes Reduced added water, minimizing the washing of polyphenols Pomace with a low content of water easier to manage Disadvantages Difficult to clean Non-continuous process with waiting periods thus exposes the olive paste to oxygen and light Requires more manual labor Longer production time from harvest to pressing Decanter centrifugation The modern method of olive oil extraction uses an industrial decanter to separate all the phases by centrifugation. In this method the olives are crushed to a fine paste. This can be done by a hammer crusher, disc crusher, depitting machine or knife crusher. This paste is then malaxed for 30 to 60 minutes in order to allow the small olive droplets to agglomerate. The aromas are created in these two steps through the action of fruit enzymes. Afterwards the paste is pumped into an industrial decanter where the phases will be separated. Water is added to facilitate the extraction process with the paste. The decanter is a large capacity horizontal centrifuge rotating approximately 3,000 rpm, the high centrifugal force created allows the phases to be readily separated according to their different densities (solids > vegetation water > oil). Inside the decanter's rotating conical drum there is a coil that rotates more slowly, pushing the solid materials out of the system. The separated oil and vegetation water are then rerun through a vertical centrifuge, working around 6,000 rpm that will separate the small quantity of vegetation water still contained in oil and vice versa. Three, two, and two and a half phases decanters With the three phases oil decanter, a portion of the oil polyphenols is washed out due to the higher quantity of added water (when compared to the traditional method), producing a larger quantity of vegetation water that needs