CONVERSION OF OILS TO MONOGLYCERIDES BY GLYCEROLYSIS IN SUPERCRITICALCARBON-DIOXIDE MEDIA

Glycerolysis of soybean oil was conducted in a supercritical carbon di oxide (SC-CO2) atmosphere to produce monoglycerides (MG) in a stirred autoclave at 150-250 degrees C, over a pressure range of 20.7-62.1 MPa , at glycerol/oil molar ratios between 15-25, and water concentrations of 0-8% (wt% of glycerol). MG, di-, triglyceride, and free fatty acid (FFA) composition of the reaction mixture as a function of time was a nalyzed by supercritical fluid chromatography. Glycerolysis did not oc cur at 150 degrees C but proceeded to a limited extent at 200 degrees C within 4 h reaction time; however, it did proceed rapidly at 250 deg rees C. At 250 degrees C, MG formation decreased significantly (P < 0. 05) with pressure and increased with glycerol/oil ratio and water conc entration. A maximum MC content of 49.2% was achieved at 250 degrees C , 20.7 MPa, a glycerol/oil ratio of 25 and 4% water after 4 h. These c onditions also resulted in the formation of 14% FFA. Conversions of ot her oils (peanut, corn, canola, and cottonseed) were also attempted. S oybean and cottonseed oil yielded the highest and lowest conversion to MG, respectively. Conducting this industrially important reaction in SC-CO2 atmosphere offered numerous advantages, compared to conventiona l alkali-catalyzed glycerolysis, including elimination of the alkali c atalyst, production of a lighter color and less odor, and ease of sepa ration of the CO2 from the reaction products.