Web Release Date: May 17,
Triacylglycerol Structure and Composition of Hydrogenated Soybean Oil Margarine and Shortening Basestocks
Food and Industrial Oil Research, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, Illinois 61604
Received for review December 22, 2004. Revised manuscript received April 12, 2005. Accepted April 13, 2005.
Abstract:
The composition and structures of triacylglycerols (TAG) in a commercially prepared hydrogenated soybean oil margarine basestock [iodine value (IV) 65, 39.7% trans fatty acids] were determined by high-performance liquid chromatography (HPLC) in tandem with atmospheric pressure chemical ionization (APCI) mass spectrometry (MS). The basestock was separated by preparative HPLC into four fractions. Fractions 1 and 4, constituting ~8% of the total, were shown to consist of LOO, PLO, and LLS and OSS and PSS, respectively (where L = linoleic, O = oleic, S = stearic, and P = palmitic). APCI will not distinguish between O, oleic cis C18:1, and E, elaidic trans C18:1. Thus, O and E may be used interchangeably in discussion of TAG isomer structures. Fraction 2 consisted of OOO and POO. Fraction 3 consisted of OOO, POO, OOS, and POS. About 80% of the total triglycerides consisted of OOO, POO, and OOS. The trans fatty acid content of the fractions was determined, and the results showed that 92% of the total trans content was found in fractions 2 and 3. A shortening basestock (IV 81.7, 31.8% trans fatty acids) was partially characterized.
Keywords: Triacylglycerols; trans fatty acids; gas-liquid chromatography (GLC); high-performance liquid chromatography (HPLC); atmospheric chemical ionization mass spectrometry (APCI-MS)
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