TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The alkyl ester products are purified by contacting the alkyl ester products with an adsorbent material, e.g. silicas or clays. The glyceride-containing feedstock is controllably dewatered at 50-100degreesC and at 99-760 mm Hg(A), and cooled to 40-85degreesC. The cooled dewatered glyceride-containing feedstock is combined with an alcohol to form a reaction mixture, and maintaining the reaction mixture for a time for esterification of the glycerides to occur.Preferred Component: The glyceride-containing feedstock comprises oils extracted from plants (e.g. brassicas, legumes, maize, mallows, flax seeds, palm nuts, soybean seeds, mustard seeds, canola seeds, rape seeds, cotton seeds, or corn seeds), fish or animals. The oils can be waste restaurant frying oils, waste automotive oils, waste industrial greases or waste industrial oils. The anhydrous alcohol is methanol, ethanol, propanol or butanol. EXAMPLE - A mustard oil (1700 kg) was sprayed with a nozzle pressure of 10plus minus5 psi into a reactor. After the mustard oil was added to the reactor, a negative pressure of 110 mmHg(A) was applied by vacuum, and the oil was dewatered by heating at 100plus minus5degreesC under negative pressure until there was no trace of bubbling at the oil surface after which, the oil was cooled to 50plus minus2degreesC. While the oil was dewatered, absolute methanol (20% w/w of the oil) (340 kg) was added to a stirred vessel and potassium hydroxide (KOH) (17 kg) was added while the methanol was agitated until the KOH was dissolved. The KOH-methanol mixture was added under vacuum to the dewatered oil, and esterification reaction proceeded for 4.5 hours while the oil was maintained in a turbulent flow by agitation, and agitation was ceased and the methylated mustard oil was maintained in the reactor for 2 hours to allow the reaction mixture to separate. Then, water (500 L) heated to 95degreesC was added to the methyl ester phase under vacuum and the mixture was agitated for 30 minutes to wash water-soluble impurities out of methyl ester reaction product. The mixture was allowed to separate over an 8-hour period into two phases. TriSyl 615(RTM: adsorbent) (2% w/w) was added to the reaction product and mixed for 30 minutes to remove any remaining impurities. The adsorbent was removed from the methyl ester reaction product by recycling the methyl esters until clarity was achieved. The methyl ester reaction product was analyzed. Analysis showed that process provided a 99% conversion of the triglyceride compounds present in mustard oil into methyl esters, 98.95% purity of the final methyl ester product and 91.8% recovery.