Semi-continuous extraction/purification of lipids by means of supercritical fluids

A method for semi-continuous extraction using supercritical carbon dioxide has been developed. In this technique, two streams, a solution of the material that will be fractionated and supercritical carbon dioxide, are coaxially introduced to a nozzle where a spray is formed. Extensive physical contact between the supercritical fluid and the feed solution is achieved in the spray thus facilitating extraction. The performance of the extractor is illustrated by the extraction of triacylglycerols (TGs) from an acetone extract of oat bran. In the extractor, the TGs are dissolved in the CO2 and removed from the precipitation unit with the stream of CO2. The target product, which is digalactosyldiacylglycerol (DGDG) is trapped in the precipitation unit. Through-put is related to the desired purity of the product. A DGDG purity of 95.4% was obtained at a solvent/feed ratio (S/F) of 48, the rate of production was then about 1 g/h. At a S/F of 200 the purity of the DGDG was 97%. (C) 1997 Elsevier Science B.V.