Sampathkumar (1986) described a process for recovering tocopherols from deodorizer sludge for use in pharmaceutical and food applications without the loss of vitamin E activity with an overall yield of 97%. It was found that urea forms an inclusion complex with all the fatty acids and glycerides of fatty acids without entrapping the sterols, tocopherols and other bulky molecules present in the deodorizer sludge or distillate.

The process comprises the heating of deodorizer sludge and a solution of urea mixture to form a urea complex of the fatty acids and glycerides of fatty acids. The mixture was cooled to precipitate the urea complex from the mother liquor containing the tocopherols, and separating the mother liquor from the precipitate. The mother liquor was further concentrated and the residual solids were separated. Extracting the mother liquor, an oil rich in tocopherol could be obtained. It was suggested that the instability of the urea complex of fatty acids in the presence of water and an acid can be used for further purification of FFA and their separation.

A similar process was described by Maza (1992) where urea was used for the separation of mixed fatty acids, sterols and tocopherols from DD with an increased yield and reduced use of organic solvents. The process comprised the sequential steps of (1) melting the DD, (2) adding the melted DD to a refluxing solution of urea and alcohol to form a mixture, (3) mixing the reaction mixture while cooling to allow formation of crystals, (4) separating the crystals, (5) drying the crystals, (6) dissolving the crystals in water to form an organic layer which is rich in mixed fatty acids and an aqueous layer containing urea and (7) separating the fatty acid layer. By applying this process, a light fraction enriched in FFA and a heavy fraction enriched in tocopherols and sterols were obtained. Urea is recovered for reuse by combining the separated aqueous solutions containing urea and evaporating the water. The key element of the invention is the first step of the process, i. e. melting of the DD providing an easily dispersed reactive liquid which is not diluted in the solvent.