Analysis of Lipid and Protein Oxidation in Fats, Oils, and Foods

During nearly 20. years of the low-/no-fat era, lipid oxidation was essentially forgotten as a stability problem. Now, the era of healthy fats focuses on reformulating foods with highly unsaturated (polyunsaturated) fatty acids (PUFAs). PUFAs are essential - they cannot be synthesized by humans and they are required for many physiological processes - but also are extremely sensitive to oxidation and can very rapidly degrade food quality, function, and nutrition by production of off-flavors and odors, loss of essential fatty acids, and co-oxidation of proteins and vitamins. Thus, a need for accurate and sensitive tracking of lipid oxidation has once again moved to the forefront in food analyses and quality control. Old "rules" of how to measure lipid oxidation do not always provide accurate pictures of lipid oxidation. Most critically, they often underestimate total oxidation levels and misrepresent active pathways. This chapter argues for a new paradigm in analysis of lipid oxidation. The main focus is on analyses used or likely to be applied in the food industry. Highly specialized methods such as electron paramagnetic resonance, nuclear magnetic resonance, and mass spectrometry requiring expensive instrumentation are not included.