Crude oil is normally processed by means of chemical or alkali refining, and established technology reliable for production of finished oil of consistent quality, regardless of the origin of characteristics of feedstock. Complete alkali or chemical refining as three basis steps, after De-gumming, first step starts with a phosphoric acid condition in a knife mixer to transform water insoluble phosphatides into hydrophilic compounds. Next, oil is mixed with caustic which, besides neutralizing oil is mixed with caustic which beside neutralizing free fatty acids, also decomposes pigments, traps phosphorus compounds trace metals, proteins and oxidizing materials. Soap stock including deleterious compound is separated by centrifugal force following a washing step mixing with water and then separating in centrifuges.
This oil goes to the second main step, bleaching, where contact with good quality bleaching earth is enough to adsorb pigments, decompose one half of remaining oxidation products, adsorb all soaps and most of phosphatides. Bleached oil flows to the third and last step, deodorization, where fatty acid, aldehyde, ketones, hydrocarbons and other unwanted materials are vaporized with stripping steam at high vacuum. Quality of the deodorized oil measured as flavor stability and other parameters is good.