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.

Graphical abstractFlavor oil emulsions fabricated by spontaneous emulsification have different droplet sizes and appearances depending on oil phase composition and surfactant type.Download high-res image (84KB)Download full-size image