*3.3. Experimental Design*

In this study, a three level Box–Behnken experiment design with response surface methodology (RSM) (Design Expert software version 13.0) was used for determining the nanoemulsion criteria. The variables included the AHE, WPI and HSO concentrations (% *w*/*v*) at three coded levels, i.e., −1, 0, +1. The specific ranges of the variables were selected according to prior knowledge and preliminary studies performed on the formulation of the hempseed oil nanoemulsion. The Box-Behnken design provided 17 experimental trials with five replications for the center point. The optimal formulations for further

stability tests and visual observations were chosen based on the droplet size distribution results of the experimental trails.
