Influence of surfactant type and thermal cycling on formation and stability of flavor oil emulsions fabricated by spontaneous emulsification

- Oil phase composition has appreciable impact on thermal stability of emulsion.
- Surfactant type has significant influence on thermal stability of emulsion.
- Thermostable emulsion can be formed under optimized conditions.

Food-grade emulsions can be fabricated using simple and inexpensive low-energy homogenization methods. In this study, we examined the influence of surfactant type (Tween 40, 60, and 80), oil phase composition (limonene-to-medium chain triglyceride ratio), and temperature (25 to 95 °C) on the formation and stability of flavor oil-in-water emulsions (10 wt% oil, 15 wt% surfactant, pH 3) fabricated using spontaneous emulsification. Transparent emulsion-based delivery systems containing ultrafine droplets (d < 40 nm) could be formed at room temperature at certain limonene contents for all three surfactants. When these emulsions were heated and then cooled, appreciable droplet growth occurred at lower limonene levels (< 60% limonene) leading to cloudiness, but ultrafine droplets were still present at higher limonene concentrations (80% limonene) leading to optical clarity. These results were attributed to the influence of oil phase composition and surfactant type on the phase inversion behavior of the surfactant-oil-water systems.

Flavor oil emulsions fabricated by spontaneous emulsification have different droplet sizes and appearances depending on oil phase composition and surfactant type.84