Quantitative Determination of trans Fatty Acid Content in Hydrogenated Edible Vegetable Oils by 13C-Nuclear Magnetic Resonance

Abstract

High resolution nuclear magnetic resonance (NMR) spectroscopy is an effective means for the determination of trans fatty acid content in hydrogenated vegetable oils. The trans fatty acid content is calculated from the number of trans double bonded carbons and average molecular weight derived directly from the spectrum of 13C-NMR and 1H-NMR, respectively. Allylic carbons were used to estimate the absolute number of trans double bonded carbons. NMR results of hydrogenated oils were compared with those obtained by IR method. Correlation coefficient of the data between ordinary IR method and NMR method was r2=0.995, and the regression equation was Y=0.986X+1.37, where X was the IR results. The trans fatty acid measured by NMR was •}6% of error, when corrected with proposed regression equation, except for two samples in which trans fatty acid contents were below 6%.