Simultaneous quantitation of FFA, MAG, DAG, and TAG in enzimatically modified vegetable oils and fats

Abstract

A novel and easy-to-implement high temperature gas chromatographic procedure for the simultaneous quantitation of free fatty acids (FFA), monoacylglycerols (MAG), diacylglycerols (DAG), and triacylglycerols (TAG) for products arising from fats and oils modification processes has been developed. The method involves silylation in the presence of pyridine at room temperature, standard injection system, and FID detection. Species were separated by carbon number and degree of unsaturation; thus, a total of 53 individual compounds could be quantified. An identification plot for unavailable triacylglycerol standard species relating relative retention time with the number of double bonds was built. Calibration curves for the quantitation of by-products (FFA, MAG, and DAG) and a calibration surface for TAG were constructed using standard solutions. Multiple internal standards were used, achieving good repeatability. The method was tested over a wide range of fatty acid unsaturation level (0 to 3 double bonds) and chain length (C14 to C18). The results achieved in real samples were in agreement with those obtained by fatty acid methyl esters (FAME) analysis and HPLC-RI. The method developed is a rapid and reliable technique to quantify FFA, MAG, DAG, and TAG in substrates and products of modification, ideal to monitor the degree of conversion in fats and oils enzymatic esterification, among others.