By using modern technology the process is simplified. The pomace, oil and vegetable water are separated by continuously centrifugating the paste. After being suitably thinned with lukewarm water, the paste is injected into centrifuges. Because of the different densities of the three substances, an immediate separation can be achieved. The process of refining includes neutralisation, decolouration and deodorising.
Neutralisation is for eliminating the excess of free fatty acids in the oil.
Minor quality oils often have an intense or abnormal colour which has to be corrected by decolouration. Olive oils that have been refined are pale in colour and not very viscous. They have little or no taste or odour and a very low acidity. Trade quality Olive oil is traded on the international market at a higher price than other vegetable oils. Consequently, adulteration of olive oil with cheaper oils is a temptation.