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 (RSDR = 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.