Document Type : Research Paper
There is considerable interest in using nano-emulsions (NEs) as delivery systems for
lipophilic bioactive ingredients. In this study, we investigated the influence of propylene glycol (PG)
on the properties of VE enriched NEs prepared using the spontaneous emulsification (SE) method.
The particle size and optical clarity of the NEs depended strongly on the co-solvent concentration.
The smallest droplets (mean diameter less than 23.5, and 262.96) and highest transparency (lowest
turbidity, 0.0069 cm-1, and 0.023 cm-1) were observed in the absence of the PG (A formulation) and the
presence of 10 wt.% PG (B formulation), respectively. However, these NEs were highly unstable to
droplet growth during storage, especially at high temperatures, which was attributed to coalescence
and Ostwald ripening. Dilution of the NEs (100× with water) before storage considerably improved
their storage stability, especially at higher storage temperatures. Undiluted NEs exhibited a sharp and
irreversible increase in turbidity upon heating: ≈75 °C and 50 °C for the systems in A formulation and
B formulation, respectively. Diluted NEs had much better thermal stability, with a sharp increase in
turbidity occurring at ≈75 °C for these systems. This study provides useful information for use in the
pharmaceutical, foods, and beverages industries.