Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/21/2008
Publication Date: 2/12/2008
Citation: Laszlo, J.A., Compton, D.L., Vermillion, K. 2008. Acyl migration kinetics of vegetable oil 1,2-diacylglycerols. Journal of the American Oil Chemists' Society. 85(4):307-312. Interpretive Summary: Vegetable oils can be altered to make products with enhanced function and value through selective modification or replacement of one or more of the fatty acid groups comprising the oil. When performing this change in the lipid’s structure, it is important to know the exact location (on the glycerol backbone of the molecule) of the altered/replaced fatty acid and that this location does not change during processing. We have found that the rate at which a fatty acid group in the center position moves to an outside position is the same whether or not there is a second fatty acid group on the molecule. With this new knowledge about the internal rearrangement of fatty acid groups, scientists can better design and control effective processing steps for manufacture of specialty vegetable oils to meet the needs of consumers.
Technical Abstract: The acyl migration kinetics of long-chain 1,2-diacylglycerol (1,2-DAG) to form 1,3-diacylglycerol (1,3-DAG) over the temperature range of 25 to 80 degrees Celsius were examined using proton NMR spectroscopy. The 1,2-DAG mole fraction of 0.32 at equilibrium was found to be insensitive to temperature, indicating that long-chain acyl group migration is neither endothermic nor exothermic. Determination of the first-order reaction kinetic parameters revealed a 1,2-DAG half life of 3425 h and 15.8 h at 25 and 80 degrees Celsius, respectively. Comparison of 1,2-DAG with 2-monoacylglycerol indicated that there is no difference between the two in the potential energy state of their respective transitions states or cyclic intermediates.