(188g) Lipid Processing Using Critical Fluids

A lipase (Novozyme 435) interesterification of soybean oil triacylglycerides with ethyl ferulate to produce feruloylated acylglycerols has been previously been described and patented. These feruloylated acylglycerols, termed SoyScreen?, are believed to have potential as natural sunscreens and as antioxidants for the cosmetic and food industry.

Critical fluid technology has been used in several ways to improve this lipid processing method. Liquid carbon dioxide (L-CO₂) has been used to purify the SoyScreen^TM product from the reaction mixture. Factors such as fractionation column length, solvent to feed ratio (S:FR) and feed rate (FR) were studied. Both by-product fatty acid ethyl esters (FAMEs) and unreacted ethyl ferulate are efficiently separated from the crude reaction mixture using a L-CO₂ counter-current fractionation method to yield an essentially pure product. In addition, to purify the ethyl ferulate used in this reaction, a method utilizing supercritical carbon dioxide in conjunction with a silica column was also developed to provide nearly snow-white ethyl ferulate used in the interesterification reaction.

Partially deacylated high oleic sunflower oil (PDHOSO) has been determined to offer some advantages over soybean oil as a starting material to produce the feruloylated acylglycerols. The PDHOSO is produced by enzymatic propanolysis and the crude product contains a mixture of mono-, di-, and triacylglcerides as well as by-product fatty acid propyl esters (FAPEs). However, before the PDHOSO can subsequently be used to produce the final feruloylated acylglycerol product, the FAPEs must be removed from the crude reaction mixture. Subsequently, a continuous counter-current fractionation L-CO₂ method was developed to remove the by-product FAPEs from the propanolysis reaction mixture. Parameters such as S:FR and FR were examined to optimize the separation. This process yielded a glyceride product purity of over 98% as well as an extract containing over 97% FAPEs.

Critical fluid technology is being studied as a potential means to enhance the synthesis of SoyScreen? by cycling CO₂ through a bed of Novozyme 435 containing triacylglycerides and ethyl ferulate. In this process, CO₂ removes FAMEs from the reaction mixture and precipitates them in a reduced pressure receiver before recycling the CO₂. In this manner, the by-product FAMEs are removed from the reaction mixture allowing the reaction to proceed further to the right than otherwise possible.