Submitted to: Supercritical Fluids International Symposium
Publication Type: Proceedings
Publication Acceptance Date: April 30, 2002
Publication Date: April 30, 2003
Citation: HOLSER, R.A., SHOGREN, R.L. CHEMICAL MODIFICATION OF STARCHES IN THE PRESENCE OF SUPERCRITICAL CARBON DIOXIDE. SUPERCRITICAL FLUIDS INTERNATIONAL SYMPOSIUM PROCEEDINGS. 2003. Technical Abstract: Starches are reacted with organic acid anhydrides to produce a variety of starch ester compounds that have both edible and industrial applications. Starch esters have previously been prepared in organic solvents such as pyridine, pyrrolidone, and dimethylacetamide. Supercritical carbon dioxide was investigated as a possible alternative to these organic solvents for the preparation of starch succinate esters. A cornstarch (10 wt% moisture) was combined with equimolar amounts of succinic, 2-octen-1-ylsuccinic, or 2-dodecen-1-ylsuccinic anhydrides in carbon dioxide at 80°C and 54 Mpa. After reaction the starch was recovered and extracted with ethanol and dried in a vacuum oven. Analysis of the reaction products by proton NMR indicated that the base catalyst, sodium hydroxide, was more effective than the acid catalyst, acetic acid, in the formation of starch esters. Additionally, succinic anhydride was substituted onto the starch to a greater extent than either of the other acid anhydrides investigated regardless of catalyst. These results suggest the possibility of using supercritical carbon dioxide in the preparation of starch esters.