Stearidonic acid (18:4n-3, SDA) is an omega-3 fatty acid that is naturally occurring in several seed oils, including Ahiflower, hemp, evening primrose and black currant. Seed oils rich in SDA are marketed as a more sustainable, cost effective alternative to omega-3 from fish oil. The refining of these oils is expected to cause the isomerization of SDA, producing related trans fatty acids. To date, there is no study describing the identification and gas chromatographic separation of the geometric isomers of SDA. In this study we have isolated all geometric isomers of SDA by silver ion HPLC (Ag+-HPLC), using up to 6 chromatographic columns in series. The structure of the purified FAMEs was determined by partial reduction with hydrazine, followed by identification of the reduction products by comparison with the retention times of available reference materials. We have determined the gas chromatographic elution order of all SDA geometric isomers under the separation conditions commonly applied for analysis of vegetable oils, and have investigated the occurrence of SDA trans fatty acids in oils rich in SDA.

Identification and occurrence in food oils of the Stearidonic acid trans fatty acids

254th National Meeting (2017)

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