Application of Infrared Spectroscopy for Characterization of Dietary Omega-3 Oil Supplements

Fish oil dietary supplements have been linked with health benefits, due to high omega-3 concentration. The sources of these effects, polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid, are almost exclusively found in seafood products. Our objectives were to characterize the composition of commercial omega-3 dietary supplements dietary supplements and to generate partial least square regression (PLSR) models using infrared spectroscopy and chemometrics. Fatty acid (FA) composition of oils was determined by FA methyl ester gas chromatography. The supplements encompassed a wide range of FA profiles and delivery methods. Infrared spectral data were collected by portable mid-infrared Fourier transform infrared (MID FT-IR) equipment. Principal components analysis (PCA) separated samples based on the type of ester present in the fish oil dietary supplements, showing a strong influence of the 1038 cm-1 band, which is typically associated with C=C and C-O stretching vibrations. In addition, PLSR was used to correlate the spectra data with GC-FAME results. PCA using the spectroscopy data allowed for tight clustering of fish oil into distinct classes, depending on the source and processing. PLSR using MID FT-IR spectra and FA composition generated multivariate models with high correlation coefficient (R ≥ 0.93), and SEP between 0.53 and 2.13 g of FA per 100 g of oil. Our results indicate that IR spectroscopy combined with chemometrics provides for robust screening of FA composition of fish oil supplements, and discriminate types of FAs esterification. © 2015 AOCS.