# Focus on the role of mixed micelles and lipid droplets in the oxidative stability of oil-in-water emulsions using size distribution Taylor dispersion analysis

## TL;DR

This study explores how mixed micelles and lipid droplets affect the stability of oil-in-water emulsions during oxidation.

## Contribution

The study introduces the use of size distribution Taylor dispersion analysis to resolve mixed micelles and lipid droplets in oil-in-water emulsions.

## Key findings

- Tween 20 forms mixed micelles enriched in surface-active lipids, largely independent of homogenization energy.
- Emulsification energy controls droplet size distribution and droplet-to-micelle oil ratios.
- Large lipid droplets act as slow-oxidizing TAG reservoirs, modulating oxidation pathways in polydisperse systems.

## Abstract

This study investigates the role of mixed micelles and lipid droplets in the oxidative stability of oil-in-water emulsions using Size Distribution - Taylor Dispersion Analysis. Tween surfactant facilitates the formation of mixed micelles containing surface-active components in non-stripped oils, whereas oil stripping suppresses their formation, indicating that these micelles are enriched in non-TAG-derived species such as DAG, MAG, and FFA. Tween 20, and to a lesser extent Tween 80, also promotes the incorporation of TAG molecules into mixed micelles, which can reorganize into small lipid droplets (<100 nm) under low-energy conditions. The fraction of oil solubilized in Tween 20 showed minimal dependence on homogenization pressure or number of passes, confirming that mixed micelles readily form under mild energy inputs. In contrast, the distribution of oil between small and larger droplets (>500 nm) is strongly influenced by emulsification energy. During oxidation, emulsions with narrow droplet-size distributions retain both their small droplet size and the proportion of non-oxidized oil within each population. In contrast, polydisperse systems exhibit an increased amount of non-oxidized oil in small droplets relative to mixed micelles, accompanied by droplet growth. These results highlight how surfactant type, mixed-micelle structure, droplet size distribution, and emulsification energy collectively govern oil partitioning and oxidative behavior in emulsions.

Image 1

•SD-TDA resolves mixed micelles and lipid droplets and quantifies oil partitioning in O/W emulsions.•Tween 20 forms mixed micelles enriched in surface-active lipids, largely independent of homogenization energy.•Emulsification energy controls droplet size distribution and droplet-to-micelle oil ratios.•Mixed micelles and small droplets seem to exhibit comparable oxidation rates.•Large lipid droplets act as slow-oxidizing TAG reservoirs, modulating oxidation pathways in polydisperse systems.

SD-TDA resolves mixed micelles and lipid droplets and quantifies oil partitioning in O/W emulsions.

Tween 20 forms mixed micelles enriched in surface-active lipids, largely independent of homogenization energy.

Emulsification energy controls droplet size distribution and droplet-to-micelle oil ratios.

Mixed micelles and small droplets seem to exhibit comparable oxidation rates.

Large lipid droplets act as slow-oxidizing TAG reservoirs, modulating oxidation pathways in polydisperse systems.