Rapid Quantitative Profiling of Lipid Oxidation Products in a Food Emulsion by ¹H NMR

Lipid oxidation is one of the most important reasons for the compromised shelf life of food emulsions. A major bottleneck in unravelling the underlying mechanisms is the lack of methods that provide a rapid, quantitative, and comprehensive molecular view on lipid oxidation in these heterogeneous systems. In this study, the unbiased and quantitative nature of ¹H NMR was exploited to assess lipid oxidation products in mayonnaise, a particularly oxidation-prone food emulsion. An efficient and robust procedure was implemented to produce samples where the ¹H NMR signals of oxidation products could be observed in a well resolved and reproducible manner. ¹H NMR signals of hydroperoxides were assigned in a fatty acid and isomer specific way. Band-selective ¹H NMR pulse excitation allowed immediate and precise (RSD_R = 5.9%) quantification of both hydroperoxides and aldehydes with high throughput and large dynamic range at levels of 0.03 mmol/kg. Explorative multivariate data modeling of the quantitative ¹H NMR profiles revealed that shelf life temperature has a significant impact on lipid oxidation mechanisms.