Streamlined Methods for the Resolution and Quantification of Fatty Acids Including Trans Fatty Acid Isomers in Food Products by Gas Chromatography

• Published in: Journal of AOAC International Vol. 92; no. 5; pp. 1301 - 1309
• Main Authors: Golay, Pierre-Alain, Giuffrida, Francesca, Dionisi, Fabiola, Destaillats, Frederic
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.09.2009
• Subjects: accuracy; analysis; Animals; capillary gas chromatography; chemistry; Chromatography, Gas; Chromatography, Gas - methods; Chromatography, Ion Exchange; Chromatography, Ion Exchange - methods; Daily Values; Dietary Fats; fatty acid composition; fatty acid esters; fatty acid methyl esters; Fatty Acids; Fatty Acids - analysis; food analysis; Food Analysis - methods; Food Chain; food composition; Food Industry; foods; Gas chromatography; health claims; human food chain; Humans; Identification and classification; Isomerism; isomers; lipid content; Lipids; Lipids - chemistry; long chain fatty acids; Methods; nutrient content; nutrition information; Plant Oils; Plant Oils - analysis; product authenticity; quantitative analysis; Reproducibility of Results; Silver; Silver - chemistry; Trans fatty acids; Trans Fatty Acids - analysis; Trans Fatty Acids - chemistry; transesterification; United States
• ISSN: 1060-3271; 1944-7922
• DOI: 10.1093/jaoac/92.5.1301

To support labeling, claims, and authenticity of food products, industry needs reliable methods for the analysis of fatty acids, including trans fatty acids (TFA). In finished products, precise quantification of TFA can be problematic due to the occurrence of various positional and geometrical isomers originating from different sources, such as animal fats or processed vegetable oils and fats. The risk of underestimating TFA amounts is particularly high when inappropriate GC conditions are used. Complex sample preparation procedures involving purification of TFA isomers by silver ion chromatography have been well-documented and used for research purposes. However, in the food industry, time and cost constraints do not permit multiple analytical steps; therefore, streamlined methods are necessary. Direct methods include preparation of fatty acid methyl esters directly from food samples without prior extraction. The appropriate resolution is obtained using high-resolution GC with a highly polar 100 m capillary column, and quantification is achieved using experimentally determined response. We found that it is possible to quantify TFA in the range of 0.01 to 5.00 g/100 g of lipids in a wide range of food products. In addition, the use of direct transmethylation, response factors, and high-resolution GC allow accurate quantification of other fatty acids, including polyunsaturated and long-chain polyunsaturated fatty acids.