QUANTITATIVE EXTRACTION OF PECAN OIL FROM SMALL SAMPLES WITH SUPERCRITICAL CARBON-DIOXIDE

A procedure to determine total oil content of pecan was developed for samples weighing 500 and 10 mg by supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent, and chilled hexane as the trapping solvent. Fatty acid methyl esters (FAMEs) were prepared f rom the total lipid fraction by using either an aliquot (500 mg starti ng weight) or the entire extract (10 mg starting weight). Total oil co ntent obtained for either sample size with SFE was similar to that obt ained with an organic solvent extraction technique. The fatty acid com position for the total lipid fraction of oils extracted with SFE was t he same as for oils extracted with organic solvents, and oil compositi on did not change during SFE. Both oil yield and fatty acid compositio n were similar to those reported previously for pecan. Samples could b e extracted and placed into FAME-derivatizing reagents in one day, and fatty acid composition of the total lipid fraction could be determine d by gas-liquid chromatography the next day. The procedure, as demonst rated for pecan, should be suitable for other oilseeds, especially tho se containing low amounts of water.