Lipid Oxidation in Food Emulsions: Analytical Challenges and Recent Developments

Lipid oxidation is one of the main causes of degradation in food emulsions. It leads to the generation of off-flavors and a concomitant reduction in shelf-life of the food products. The multiscale complexity of lipid oxidation reactions in food emulsions has raised the need to develop new methodological approaches. In this chapter, we will discuss how the recent analytical advancements have opened new avenues for the identification and quantification of multiple key oxidation products and for the spatio-temporal resolution of the reactions. After shortly introducing the challenges related to lipid extraction prior to analysis, we will first focus on the use of electron spin resonance for the early assessment and of nuclear magnetic resonance for the simultaneous analysis of multiple oxidation products. Then, we will discuss the potential of chromatographic and mass spectrometry approaches to monitor non-volatile and volatile oxidation products and assess the contribution of minor surface-active lipid species. Finally, the recent developments in electron and fluorescence microscopy to monitor the structural changes associated with lipid oxidation and the localization of the reaction sites in emulsions will be discussed.