ANALYTICAL SUPERCRITICAL-FLUID EXTRACTION WITH LIPASE CATALYSIS - CONVERSION OF DIFFERENT LIPIDS TO METHYL-ESTERS AND EFFECT OF MOISTURE

The fat content of lipid-containing samples has been determined by ext raction of the fat with supercritical carbon dioxide, followed by enzy me-catalyzed methylation of the fat under supercritical conditions, pr ior to gas chromatography (GC) analysis. This study was initiated to d etermine the effect of moisture content on the extraction and conversi on of lipids in oilseed and meat samples to their fatty acid methyl es ter (FAME) derivatives. These samples were freeze-dried or mixed with Hydromatrix and compared with untreated control samples by employing t he above-described supercritical fluid extraction-reaction sequence. P articular attention was focused on minor constituents, such as phospho lipids and cholesteryl esters, to see if they could be extracted and d erivatized by the above technique. Recoveries and reaction conversions of the lipid species were determined with the aid of GC, high-perform ance liquid chromatography, and supercritical fluid chromatography for analyses of the extracted lipids. Total fat Values were higher from t he freeze-dried meat and oilseed samples than from samples mixed with Hydromatrix or left untreated. Extraction of cholesteryl esters was be tter than 90%, and conversion of the cholesteryl esters to FAME was 93 % or higher. Extraction of phosphatidic acid was only 88% compared to more than 90% recoveries for the other phospholipid species. FAME conv ersion was better than 96% for all phospholipid samples in the study.