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Title: CHARACTERIZATION OF STRUCTURED TRIACYLGLYCEROLS BY SILVER-ION HPLC

Author
item Adlof, Richard
item List, Gary

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2003
Publication Date: 5/20/2003
Citation: ADLOF, R.O., LIST, G.R. CHARACTERIZATION OF STRUCTURED TRIACYLGLYCEROLS BY SILVER-ION HPLC. AMERICAN CHEMICAL SOCIETY. 2003. Abstract p. 36.

Interpretive Summary:

Technical Abstract: The amounts and types of triacylglycerols (TAGs) in the oil phase of margarines and spreads are considered responsible for such properties as spreadability, resistance to water/oil loss and melting at body temperature. Hydrogenation of vegetable oils has traditionally been used to reduce the unsaturation of the oil TAGs and to produce oils containing TAGs with the sharp melting points required for their use as base feedstocks. Over the past 25 years, a number of economic, health and consumer-driven factors have stimulated research aimed at reducing the levels of trans fatty acids formed during the hydrogenation of vegetable oils. Alternatives to hydrogenation include interesterification, blending of tropical and liquid vegetable oils, fractionation and, more recently, development of structurally modified oils by transgenic or conventional plant breeding methods. Biological aspects (absorption and metabolism) of these structurally modified TAG oils can be related to FA chain length, unsaturation and location on the glycerol backbone of the TAG. Ag-HPLC, utilizing columns packed with 5-10m Nucleosil SAJ (phenylsulfonic acid groups bonded to a silica substrate) or similar substrate in which the sulfonic acid protons have been exchanged with Ag ions has, over the last decade, proven to be a tremendously powerful technique for the analytical separation of cis and trans geometric and positional fatty acid methyl ester (FAME) and triacylglycerol (TAG) isomers. Ag-HPLC has been applied to the separation/quantitation of cis and trans fatty acid methyl esters, FAME positional isomers from partially hydrogenated vegetable oils, conjugated FAME, FAME labelled with deuterium atoms on the double bond carbons, TAG isomers and to separate FAME or TAG mixtures containing FAs of widely-differing chain lengths. Ag-HPLC has been found to be a powerful technology to characterize complex TAGs, to isolate specific components for further analysis by DSC [relating TAG structure to TAG mp's and crystalline form(s)] or NMR (Solid Fat Content) and, with proper control of solvent composition, for semi-preparative (5-10 mg per run) separations. Ag-HPLC can also be utilized to analyze TAGs differing only in the location of the FA(s) in the molecule and results are certainly comparable to and more rapid than those achieved by lipolysis/gas chromatography. We found Ag-HPLC to be a rapid and reproducible method to analyze a variety of structured TAG isomers (synthesized and/or isolated), with a detection limit of <0.5%.