Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/1996
Publication Date: N/A
Interpretive Summary: Several types of chemicals can be derived from the reaction of oils from seeds to produce industrially useful compounds. A reaction called glycerolysis is used to prepare compounds called monoglycerides from vegetable oils. These compounds are widely used in food products and other commercial applications. In this study, an alternative method has been developed for producing monoglycerides from vegetable oils by conducting the reaction in a high pressure atmosphere of carbon dioxide. This method of production overcomes some of the problems associated with the traditional method of producing monoglycerides, namely the elimination of metallic catalysts after completion of the reaction, and off-flavor and -color in the reaction products (monoglycerides). The described research shows that many oils can be successfully converted to give high yields of monoglycerides, particularly at a specific pressure, temperature, ratio of reactants to products, and water content in the reaction system. This production method is environmentally compatible and uses high pressure carbon dioxide as the reaction medium, thereby eliminating the generation of certain waste products associated with the traditional manufacturing process.
Technical Abstract: Glycerolysis of soybean oil was conducted in a supercritical carbon dioxide (SC-CO2) atmosphere to produce monoglycerides in a stirred autoclave at 150-250 deg C, over a pressure range of 20.7-62.1 MPa, at glycerol/oil molar ratios between 15-25, and water concentrations of 2, 4% (wt. % of glycerol). Mono-(MG), di-(DG), triglyceride (TG), and free fatty acid (FFA) composition of the reaction mixture as a function of time was analyzed using supercritical fluid chromatography. Glycerolysis did not occur at 150 deg C, but proceeded to a very limited extent at 200 deg C within 4 h reaction time; however, it did proceed rapidly at 250 deg C. At 250 deg C, MG formation decreased significantly (p less than 0.05) with pressure and increased with glycerol/oil ratio and water concentration. A maximum MG content of 45.6% was achieved at 250 deg C; 20.7 MPa, a glycerol/oil ratio of 25 and 4% water after 4 h. These conditions also resulted in the formation of 13% FFA. Conducting this industrially important reaction in SC-CO2 atmosphere offered numerous advantages, compared to the conventional alkali-catalyzed glycerolysis, particularly with respect to post reaction processing and product quality.