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

Abstract

Finding 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 1 H, 13 C, and 31 P 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 CO 2 system. Compositional distribution analysis, quantified by aliphatic carbons with 13 C NMR, showed that HMMS is composed of more unsaturated fatty acids, comprised of polyunsaturated fatty acids (PUFA) (60 AE 1.1%) and monounsaturated fatty acids (MUFA) (22 AE 0.8%), than saturated fatty acids (18 AE 0.9%). The 31 P NMR quantification of HMMS demonstrated that, out of the total amount of monoacylglycerols (MAG), they are composed of 21 AE 2.9% of 2-MAG and 4 AE 0.3% of 1-MAG. Among the three techniques, 31 P 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.Keywords 1 H NMR Á 13 C NMR Á 31 P NMR Á Enzymatic alcoholysis Á Propylene glycol monoester Á Monoacylglycerols J Am Oil Chem Soc (2020) 97: 125-133.Supporting information Additional supporting information may be found online in the Supporting Information section at the end of the article.