Counter-current liquid carbon dioxide purification of a model reaction mixture

The enzymatic reaction of soybean oil (SBO) triacylglycerides (TAGs) with ethyl ferulate (EF) produces the product feruloylated acylglycerols, called SoyScreen™ as well as by-product fatty acid ethyl esters (FAEEs). Both the unreacted EF as well as the by-product FAEEs must be removed from the mixture before the feruloylated acylglycerols can be used as natural sunscreens and/or antioxidants. This research investigated the use of a continuous liquid carbon dioxide (L-CO2) counter-current fractionation method to purify a model mixture representing the crude enzymatic mixture from the synthesis of SoyScreen™. The effect of column length, solvent to feed ratio (S:FR) and feed rate were examined. Raffinate purity increased with both column length and S:FR. When the feed rate was doubled while the S:FR was held constant, there was essentially no loss of raffinate purity. Using L-CO2 (23–25 °C and 11.0 MPa), a 120 cm long packed column, a S:FR of ca. 11.9, the raffinate was essentially free of both EF and FAEEs at feed rates of either 0.464 or 0.927 g/min with ca. 90% yield.