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ARS Home » Research » Publications at this Location » Publication #81516
Title: TOTAL FATTY ACID ANALYSIS OF VEGETABLE OIL SOAPSTOCKS: SFE/SFR VS THE AOCSOFFICAL METHOD

Author
item TAYLOR, SCOTT
item Snyder, Janet
item Holliday, Russell
item KING, JERRY

Submitted to: Association Official Analytical Chemists Annual Intrl Meeting & Exposition
Publication Type: Abstract Only
Publication Acceptance Date: 9/11/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Soapstock, a residue from the alkali refining of vegetable oil, is a much cheaper by-product than the edible oil from which it is obtained; however, it is of commercial value as a source of fatty acids. The value of soapstock is determined by its total fatty acid content and this can vary according to the method of refining. Traditionally, the total fatty acid content of soapstock has been determined by the AOCS Official Method G 3-53, which is a gravimetric analysis, taking 5-6 hours to perform. We have applied supercritical fluid extraction coupled with supercritical fluid reaction (SFE/SFR) to determine the total fatty acid content of vegetable oil soapstocks. SFE/SFR was conducted on two different commercially available extractors using an in-situ lipase to form the fatty acid methyl esters (FAMES). Quantitation was based upon the calculated sum of all fatty acids from the gas chromatography profiles of the FAMES and the results were compared to gravimetric data. In addition, both the supercritical fluid and organic solvent-derived extracts were qualitatively characterized by capillary supercritical fluid chromatography (SFC). SFC was further utilized for quantitative analysis of the soapstocks by using an internal standard and determining response factors for fatty acids, mono-, di- and triglycerides. The above SF-based techniques reduced analysis time and provided better characterization of the extracts.