Nuclear Magnetic Resonance Spectroscopy: A Versatile Tool for Qualitative and Quantitative Analysis of an Emulsifier Mixture of Soybean Oil

Abstract

AbstractFinding a fast, reliable, and reproducible approach for an accurate analysis of complex lipid mixtures of emulsifiers is crucial for the food and beverages, pharmaceuticals, personal care products, cosmetics, and agrochemicals industries. In the current study, a comprehensive qualitative and quantitative nuclear magnetic resonance (NMR) spectroscopy analysis of a high monoester mixture of soybean oil (HMMS) was conducted using 1H, 13C, and 31P NMR of 2‐chloro‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaphospholane (CTDP) derivatives. The HMMS was produced by enzymatic alcoholysis of soybean oil and 1.2‐propanediol in a supercritical CO2 system. Compositional distribution analysis, quantified by aliphatic carbons with 13C NMR, showed that HMMS is composed of more unsaturated fatty acids, comprised of polyunsaturated fatty acids (PUFA) (60 ± 1.1%) and monounsaturated fatty acids (MUFA) (22 ± 0.8%), than saturated fatty acids (18 ± 0.9%). The 31P NMR quantification of HMMS demonstrated that, out of the total amount of monoacylglycerols (MAG), they are composed of 21 ± 2.9% of 2‐MAG and 4 ± 0.3% of 1‐MAG. Among the three techniques, 31P NMR spectroscopy proved to be a practical methodology with high reproducibility for the precise detection and quantification of partially esterified glycerols and free fatty acids in complex lipid mixtures.