Synthesis of fatty acid starch esters in supercritical carbon dioxide

This manuscript describes an exploratory study on the synthesis of fatty acid/potato starch esters using supercritical carbon dioxide (scCO2) as the solvent. The effects of process variables such as pressure (6–25 MPa), temperature (120–150 °C) and various basic catalysts and fatty acid derivatives (methyl- and vinyl esters and anhydrides) on the degree of substitution (DS) were explored in a batch reactor set-up. Products with a broad range of DS values (0.01–0.31) were obtained, the actual values depending on process conditions, type of catalyst and the fatty acid reagent. The combination of K2CO3 and vinyl laurate gave the highest DS values (DS = 0.31 at 150 °C, 8 MPa). The introduction of the fatty acid chains has a profound effect on product properties like hydrophobicity and thermal behavior.