C Nuclear Magnetic Resonance Spectroscopy to Determine Fatty Acid Distribution in Triacylglycerols of Vegetable Oils with High - Low Oleic Acid and High Linolenic Acid

ABSTRACT

Carbon-13 nuclear magnetic resonance (¹³C NMR) spectroscopy was applied to determine the fatty acid positional composition of triacylglycerols in vegetable oils with oleic acid percentages higher and lower than 50% and with linolenic acid percentages higher than 5%.

In particular, conventional ¹³C NMR spectroscopy which applies the basic one-pulse sequence for signal averaging, was used to determine on the basis of carboxy and unsaturated carbon resonances, the compositions of two different pools of fatty acids at the 1,3- and 2-positions of triacylglycerols.

The results confirmed that the chains at 1,3- and 2- triacylglycerol positions deviated from the 1,3-random-2-random distribution pattern at variable extents depending on the chain concentration in the total triglyceride of oil samples. However, two factors were likely to regulate the chain distribution between 1,3- and 2-glycerol positions, namely the concentration of fatty acids in the total triglyceride and their positional specificity.

Keywords:

C NMR, fatty acids, positional distribution, triacylglycerols, vegetable oils.