|Holliday, Russell - FORMER ARS EMPLOYEE|
Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: April 25, 2000
Publication Date: April 25, 2000
Citation: LIST, G.R., NEFF, W.E., HOLLIDAY, R.L., KING, J.W., HOLSER, R.A. HYDROGENATION OF SOYBEAN OIL TRIGLYCERIDES: EFFECT OF PRESSURE ON SELECTIVITY. ANNUAL MEETING AND EXPO OF THE AMERICAN OIL CHEMISTS' SOCIETY. 2000. Technical Abstract: Soybean oil contains five triglycerides accounting for over 70% of the total. These include LLL, LLO, LLP, LOO and LOP and their isomers (where L=linoleic, O=oleic, P=palmitic). High Performance Liquid Chromatography (HPLC) analysis of samples taken during a typical hydrogenation run in which the iodine value (IV) was reduced at a much faster rate than the linolenate containing triglycerides. Hydrogenation proceeds through definite pathways rather than by random saturation of fatty acids within the triglyceride molecules. Pressure has a significant effect on the course of hydrogenation. At higher pressures (500 lbs.), the reaction is truly non-selective, since di- and tri- saturated glycerides are formed at about 70 IV, whereas, at 50 psi, the reaction becomes selective. At higher pressures, fat functionality and solid fat result primarily from di- and tri- saturated triglycerides as well as trans containing triglycerides. At tlower pressures, functionality results from trans acid triglyceride formation. Although the reactivity of linoleate containing triglycerides followed the pattern 6 double bonds>5 double bonds>4 double bonds, other factors may be important. For example, LLP is reactive and undergoes hydrogenation; LLS remains unchanged. Triolein, which comprises less than 3% of the total triglyceride in natural soybean oil, is a significant product of hydrogenation, which suggests that LLL and LLO are reduced directly while adsorbed on the catalyst surface.