A comparison of oil and fat content in oilseeds and ground beef—using supercritical fluid extraction and related analytical techniques

Abstract

A supercritical fluid extraction (SFE) has been applied for the determination of total fat content of five different oilseed matrices (soybeans, sunflower, safflower, cottonseed and rapeseed) and ground beef samples containing approximately 10, 20 and 30% fat by weight. Lipid content was determined using both gravimetric analysis as well as the sum of all fatty acids, expressed as triglycerides, from the gas chromatography (GC) profiles of the fatty acid methyl esters (FAMEs). The latter analysis is required by the Nutritional Labeling and Education Act of 1990 which redefined the determination of fat for nutritional labeling purposes. The oilseed results are compared to data from a collaborative study by the American Oil Chemists Society (AOCS) and the Association of Official Analytical Chemists International (AOAC). The collaborative study data were determined by both AOCS Official Methods and by SFE. All of our data yielded higher oil recoveries than the collaborative study data obtained via AOCS official methods and SFE with neat carbon dioxide (CO 2). However, our results are in excellent agreement with the collaborative study data obtained by SFE with ethanol-modified CO 2 and the Federation of Oil, Seeds and Fats Association International method. The ground beef results are compared to previously published reports from our laboratory. They show that fat determination using GC–FAME analysis is equivalent to the gravimetric analysis results and has the additional benefit that different types of fat (i.e. saturated and monounsaturated) can also be determined in addition to total fat. Hence, the results from this study advocate the use of SFE as a suitable replacement for traditional organic solvent extraction in the determination of fat/oil content in agriculturally-derived products.