Recent advances in lipid oxidation of bulk oils: Current insights and unresolved challenges

Lipid oxidation remains a major challenge in the food industry due to its detrimental effects on nutritional value, shelf life, and safety of edible oils. While the radical-based chemical mechanisms of lipid oxidation have been extensively studied, recent research highlights the importance of physical and supramolecular factors in bulk oils. This review provides an updated synthesis of current knowledge on lipid oxidation pathways, antioxidant mechanisms, and insights into the role of association colloids, particularly reverse micelles in bulk oils. Evidence indicates that association colloids act as reaction centers by concentrating water, hydroperoxides, and pro-oxidant metals at the oil–water interface, thereby accelerating radical initiation and propagation. Conversely, these interfacial structures may also enhance oxidative stability by promoting the targeted localization and synergistic action of antioxidants at critical reaction sites. The review discusses how intrinsic factors such as oil composition, amphiphilic constituents, water content, and oxygen solubility, together with extrinsic conditions, shape colloidal organization and oxidation kinetics. Special attention is given to the molecular structure of antioxidants, including polarity, spatial orientation of functional groups, and their impact on antioxidant efficiency, induction period extension, cutoff effects, and synergism. Recent advances in monitoring oxidation, including approaches targeting antioxidant depletion, are also addressed. Finally, key knowledge gaps and future research directions are identified, emphasizing the need for advanced structural characterization techniques and kinetic modeling to elucidate colloidal dynamics during oxidation. A deeper understanding of these interfacial and supramolecular phenomena is essential for developing more effective and sustainable strategies to control oxidation in bulk oils.