TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The process utilizes a zinc aluminate of spinel type, corresponding to the formula ZnAl2O4, xZnO or yAl2O3 (where x and y comprises 0-2), as catalyst.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The process utilizes a zinc aluminate of spinel type, corresponding to the formula ZnAl2O4, xZnO or yAl2O3 (where x and y comprises 0-2), as catalyst.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The transesterification step is operated by: catalysis in batch reactor, or continuous catalysis in fixed bed. The process comprises: introducing vegetable oil and methanol in ascending stream in a preheated reactor at 170-250 degrees C with a pressure of 3-6 MPa, a VVH (volume of oil/volume of catalyst/hour) of 0.3/1 to 3/1 and with respect to the weight ratio of alcohol/oil of 2/1 to 0.1/1; performing detention in the exit of the reactor to eliminate at least partially the excess methanol and the formed glycerol is eliminated by simple static decantation; and converting the obtained methyl esters at 85-97 %. The reaction in the second stage of catalysis is carried out in the same operating conditions to the first stage of catalysis to attain a conversion in methyl esters of 97.5-99.5 %. The acetalization step is carried out between the glycerol obtained from the transesterification step and an aldehyde, a ketone or a derivative of the aldehyde or of the ketone, in the presence of an acid catalyst (without previous treatment of glycerol). EXAMPLE - Rape oil was transesterified by methanol according to the procedure as described in FR-B-2 752 242. In a fixed bed of the reactor (heated to 200 degrees C) (that contains the extrudes (70 ml) constituting zinc aluminate), rape oil (35 ml) and absolute methanol (40 ml) were introduced. The pressure was maintained at 50-60 bar. The reaction mixture was evaporated and majority of the glycerol was eliminated by decantation. The fraction of methyl esters was subjected to the second stage of catalysis under identical operating conditions. The resultant product of the second stage of catalysis was completely free from excess of methanol. The second minority fraction of glycerol was obtained by decantation and was mixed with the product obtained form the first step of catalysis. The glycerol was next treated under vacuum to eliminate the traces of methanol.