Markers of conjugated octadecatrienoic acids in Raman spectra of vegetable oils: diagnostics of punicic and α-eleostearic acids

It is shown for the first time that using the method of Raman spectroscopy allows one to determine the content of conjugated octadecatrienoic (K-C18:3) acids in oil at their content of 8 wt. % at least. It is found that it is possible to reliably distinguish the isomers of the K-C18:3 acids containing conjugated (in punicic and α-eleostearic acids) and non-conjugated (in α-linolenic acid) C=C bonds by their Raman spectra. The obtained results can be used to develop efficient and non-destructive techniques for analyzing the composition and quality of oils, which contain conjugated octadecatrienic polyunsaturated fatty acids, and dietary supplements based on them.