TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The primary transesterification is carried out using oil or a vegetable/animal fat or a mixture of glycerides whose acid index is more than 2, ethanol having water content of 3000-5000 ppm with ethanol/oil stoichiometric ratio of 1.3:2, preferably 1.6:1.8. The catalyst is obtained by dissolution of a strong base in an alcohol, or from a metal alcoholate of alkaline metal, or from metallic compound like alcoholate, alkyl and/or oxide, preferably the sodium methylate in methanol solution. The temperature of first and second transesterifications is 20-100degreesC. The reaction time of the first transesterification by batch mode, which permits to reach thermodynamic equilibrium, is 40-160 minutes. The natural decantation of glycerin is performed at the medium temperature of 40-60degreesC. The quantity of ethanol used corresponds to ethanol/oil stoichiometric ratio of 0.3-1, preferably 0.5-0.7. The time of catalysis during the second transesterification is 20-45 minutes. The evaporation of ethanol is carried out in a falling film evaporator at a temperature of less than 120degreesC with a stay time of less than 1 minute. During purification, a first neutralizing wash is performed using a strong mineral acid followed by washes with pure water. EXAMPLE - In a glass reactor, agitated and equipped with a bottom outlet and heated to 70degreesC, were introduced refined food quality colza oil (1000 g) and ethanol (266 g) containing water (3000 ppm) with an alcohol/oil stoichiometry of 1.7. Then methanolic solution (10 g) with 30% sodium methylate was introduced. The agitation and the temperature of 70degreesCplus minus2degreesC were maintained for 60 minutes. The reaction medium was decanted at around 60degreesC. After 15-20 minutes of decantation, a glycerinous solution (95 g) made up of glycerin, ethanol, ethyl esters, soaps of sodium and alcoholates (mixture of methylate, ethylate, and glycerate) of sodium was tapped out to provide an esters mixture containing ethyl and methyl esters (91.5 wt.%), triglycerides (0.9 wt.%), diglycerides (2.6 wt.%), monoglycerides (3.7 wt.%) and sterols and esters of sterols (1.3 wt.%).    Ethanol (93 g) containing approximately 3000 ppm of water having an ethanol/starting oil stoichiometry of 0.6 and sodium methylate in solution at 30% in methanol (3.33 g) were added to the ester phase. The medium was agitated at 60degreesC for at least 30 minutes, where the formed glycerin remained soluble in the reaction medium. At the end of this stage the mixture contained (in wt.%): ethyl and methyl esters (97.5); triglycerides (less than 0.1); diglycerides (0.2); monoglycerides (0.7); sterols and esters of sterols (1.6). The excess of ethanol was evaporated in a falling film evaporator under the operating conditions of: rate of feed at 600 ml/hour; falling film temperature set at 100degreesC; pressure at 160 mm of mercury; average stay time for 15-20 seconds. Under these conditions, no retro-reaction was noted. The water content of distilled ethanol was lesser than 400 ppm.    The reaction mixture was introduced into a reactor equipped with bottom outlet and was heated to 60degreesC. Deionized water (30 g) was added for 5 minutes and decanted for 15-20 minutes. The aqueous phase enriched in alcohol, glycerin and sodium salts was tapped out. The operation was repeated until obtaining a pH value of aqueous solution 7-8. The obtained mixture of esters comprised (in wt.%): ethyl and methyl esters (97.6); triglycerides (less than 0.1); diglycerides (0.2); monoglycerides (0.6); sterols and esters of sterols (1.6).