Physical properties of beeswax-oleic acid mixture nanoemulsions as affected bylipid ratio and concentration of emulsifier

Lipid nanoemulsion is an effective system for improving or extending the functional performance of a composite coating or film since the small particle size causes the lipids to be evenly dispersed into the matrix. This study aimed to examine the effect of the ratio of BW: OA and the concentration of Tween 80 on the physical characteristics of the resulting lipid nanoemulsion. Lipid mixture nanoemulsion was prepared from beeswax (BW) and oleic acid (OA) in various ratios, of 100:0, 75:25, 50:50, and 25:75. Tween 80 as a surfactant was added at concentrations of 2.5%, 5.0%, 7.5%, and 10%. The characteristics of the nanoemulsion were determined by measuring the viscosity, particle size, polydispersity index (PDI), zeta-potential, and stability of the nanoemulsion. Lipid ratio BW:OA and surfactant concentration greatly affected the viscosity, particle size, PDI, zeta-potential, and stability of nanoemulsions. At a higher BW amount than oleic acid, increasing the concentration of Tween 80 did not affect the nanoemulsion viscosity, but decreased the particle size, PDI value, and zeta-potential value. On the other hand, in nanoemulsions with an OA ratio greater than BW, an increase in Tween 80 increased the viscosity, particle size, and PDI value. Nanoemulsions with small particle sizes did not undergo separation when tested by the Freeze-Thaw method. These results showed that the particle size and PDI values determined the stability of the nanoemulsion. From this study, it was found that formulation largely determined the characteristics of nanoemulsions.