Microemulsions based on peony (Paeonia suffruticosa Andr.) seed oil and its fatty acids: Product development and stability enhancement

Abstract

Peony (Paeonia suffruticosa Andr.) originated in China and has long been popular worldwide as an ornamental crop. In recent years, peony seed oil (PSO) as edible oil has received extensive attention due to its richness in unsaturated fatty acids, especially α-linolenic acid (ALA). In this work, fatty acid mixture-1 (FAM-1) and fatty acid mixture-2 (FAM-2) with different ALA concentrations were prepared from PSO by saponification and freezing crystallization. Pseudo-ternary phase diagrams were constructed to determine the composition and proportions of microemulsions (MEs), which were used to embed PSO and FAM. Based on pseudo-ternary phase diagrams, PSO ME prepared possessed a droplet size of 54.6 nm using a mixture of Tween 80 and Span 80 as the surfactant, while FAM-1 ME and FAM-2 ME owned droplet sizes of 30.1 and 29.7 nm using Tween 20 as the surfactant, respectively. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) analysis confirmed that the MEs had good dispersibility, and rheological analysis demonstrated excellent resistance to shearing rate changes. Besides, three MEs all exhibited good stability at 4 °C by microemulsification during the 60-day storage period in terms of droplet size, pH, and electrical conductivity. The water solubility and viscosity exhibited by the three synthetic MEs showed large potential to expand the application in cosmetics, medicine, and food industry.