Lipid Oxidation Mechanisms in Emulsion Systems

Lipid oxidation in emulsion systems arises from complex free-radical chain reactions that degrade polyunsaturated lipids into off-flavours, toxic compounds and nutritional losses. In oil-in-water emulsions, initiation often occurs at the oil–water interface, where transition metals or peroxyl radicals abstract hydrogen atoms from lipid chains to form lipid hydroperoxides. During propagation, these hydroperoxides decompose into reactive oxygen species that further attack neighbouring lipids. Physical parameters such as droplet size distribution, interfacial thickness and the nature of emulsifiers modulate the rate and location of oxidation. Mass transport phenomena—including diffusion through the aqueous phase, collision-exchange between droplets and micelle-assisted transfer—govern the movement of pro-oxidants and antioxidants. Antioxidant efficacy depends critically on partitioning at the interface, where natural phenolics and designed amphiphiles can intercept radical species. Emerging strategies focus on interfacial engineering and novel delivery vehicles to localise antioxidants precisely where lipid radical formation is most active. These advances are crucial for improving the shelf life and nutritional quality of food emulsions and for the stability of lipid-based drug formulations.

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Lipid Oxidation Mechanisms in Emulsion Systems publication trend

The graph below shows the total number of articles in lipid oxidation mechanisms in emulsion systems across all publications each year (not limited to Nature Index journals).

Technical terms

Emulsion: A mixture of two immiscible liquids in which one is dispersed as droplets within the other.

Oil-in-water emulsion: System in which oil droplets are dispersed in an aqueous continuous phase.

Lipid hydroperoxide: Primary oxidation product formed when lipid radicals react with molecular oxygen.

Interfacial region: The boundary layer between oil and water phases where oxidation initiation is often concentrated.

Free radical chain reaction: Sequence of initiation, propagation and termination steps by which lipid radicals multiply.

Antioxidant: Substance that donates electrons or hydrogen to neutralise free radicals and inhibit oxidation.

Pickering particle: Solid colloidal particle that adsorbs at the oil–water interface to stabilise emulsions and can carry antioxidants.

References

1. Lipid oxidation in emulsions: New insights from the past two decades. Progress in Lipid Research (2024).
2. Targeting Interfacial Location of Phenolic Antioxidants in Emulsions: Strategies and Benefits. Annual Review of Food Science and Technology (2023).
3. Tiny, yet impactful: Detection and oxidative stability of very small oil droplets in surfactant-stabilized emulsions. Journal of Colloid and Interface Science (2023).
4. Mass Transport Phenomena in Lipid Oxidation and Antioxidation. Annual Review of Food Science and Technology (2017).
5. Oxidative Stability in Lipid Formulations: a Review of the Mechanisms, Drivers, and Inhibitors of Oxidation. AAPS PharmSciTech (2022).
6. Pickering particles as interfacial reservoirs of antioxidants. Journal of Colloid and Interface Science (2020).