Rapid quantitation of thermal oxidation products in fats and oils by ¹H‐NMR spectroscopy

Abstract

This work describes the application of high‐resolution proton nuclear magnetic resonance (¹H‐NMR) spectroscopy to the study of the thermal peroxidation of beef tallow and corn oil under standardized conditions. The approach provides a rapid, quantitative method for determining the degree of oxidation of unsaturated fatty acids in animal and vegetable fats and oils by quantitating the decreasing intensities of ¹H‐NMR peaks for allylic and olefinic protons in unsaturated fatty acid chains of triglycerides and the increasing peak intensities of hydroperoxide and saturated and α,β‐unsaturated aldehydic protons in relation to the less labile protons in the triglyceride molecule. Two‐dimensional correlation spectroscopy analysis of highly oxidized beef tallow (180°C for 24 h) suggested that the unsaturated aldehydes that persisted were apparently associated with carboxy groups.