TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - - Preferred Composition: The fuel comprises 0.75-85 vol.% modified triglycerides.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: Alcoholates, hydroxides, oxides, carbonates, and hydrocarbonates of earth metals or alkaline earth metals, or ion exchange resins of hydroxide ion cycle are used as alkaline catalysts. Mineral acids, Lewis acids or organic sulfonic acids, and ion exchange resins of hydrogen ion cycle are used as acidic catalysts. Lower temperature limit of the transesterification is 20 degrees C, the upper temperature limit is the boiling point of the carboxylic acid ester used. By the reaction of a triglyceride of biological origin, or the mixture of such triglycerides, which optionally comprises mono- and diglycerides and free fatty acids of biological origin, with glycerol- optionally comprising alcohol and/or water - or with triacetylated glycerol prepared in advance from such glycerol characterized in that the free hydroxy groups formed following the glycerolysis/interesterification are acylated with a carboxylic acid ester, optionally incorporating at least one carbon-carbon double bond, and optionally the alcohols and fatty acids obtained as side products are removed with washing. The acylation reaction is carried out between 20 degrees C and the boiling point of the carboxylic acid ester. EXAMPLE - To the mixture of refined anhydrous sunflower oil (885 g) and methyl acetate (148 g), anhydrous potassium carbonate (20 g) was added. The mixture was agitated for 2 hours at 50-55 degrees C. After cooling, potassium carbonate was filtered off, and following the addition of acetic acid (10 g) the unreacted methyl acetate is evaporated. The residue was washed with sodium bicarbonate solution (2x100 ml), dried with sodium sulfate, and vacuum-distilled. A product (945 g), mixture of diacetylated triglycerides and fatty acid methyl esters, is obtained. It had a kinematic viscosity of 6.5 cSt at 40 degrees C and a turbidity point of - 6 degrees C.