Effect of Oil-Phase Volume Fraction on Rheological Properties of Pistacia Lenticus Fruit Oil-in-Water Emulsion Intended for Healing Wounds

Abstract

Oil-in-water emulsions with different internal phase concentrations of Pistacia lentiscus fruit oil (PLFO) were investigated. These emulsions could be useful as a cream for healing wounds after laser skin resurfacing. Microscopic analysis and rheological measurements were employed to assess the effect of PLFO content on the emulsion properties for 24 hours and one year of storage in the refrigerator. Three emulsions were prepared with 5, 10, and 20% of PLFO. An increase in the internal phase concentration led to an increase in the size of oil droplets (from 1.07 to 2.24 µm) and their concentration in the aqueous phase, which significantly influenced the viscosity and stability of emulsions. However, the high content of PLFO (20%) led to a non-homogeneous distribution of the droplet size, which decreased the viscosity and stability of the emulsion. Furthermore, the creep-recovery tests were carried out to analyze the viscoelastic behavior of emulsions. The Burger model was applied for simulations using a function of PLFO concentration. The elastic character corresponds to the gel internal network structure of emulsion. The elasticity increased with the oil concentration, indicating that the strengthening of the structure of emulsion. The elastic behavior retains in time, suggesting that PLFO influences the emulsion stability. However, high oil concentration resulted in a weakening of the structure. One of the most significant findings of this study is that the emulsion containing 10% was most stable with time and can easily be transformed into liquid, which makes it useful for the skincare formulations due to release the active compounds.