The Influence of Zinc Oxide Concentration and Stirring Time on the SPF and Physicochemical Properties of Green Tea Leaf Extract Nanoemulgel

This study evaluated the effects of zinc oxide (ZnO) concentration and stirring time on the photoprotective and physicochemical properties of a green tea (Camellia sinensis) leaf extract nanoemulgel. Formulations containing 1–5% ZnO were prepared using a self-nanoemulsifying drug delivery system (SNEDDS) with stirring times of 15 and 45 min. The formulations were evaluated for sun protection factor (SPF), pH, density, and homogeneity, followed by two-way analysis of variance. The selected formulation was further characterized for viscosity and particle size. ZnO concentration and stirring time significantly affected SPF (p < 0.05), while ZnO concentration significantly affected pH and density. The 5% ZnO formulation stirred for 15 min exhibited the highest SPF (17.47) and a mean particle size of 147.77 nm. However, phase separation occurred during storage, whereas formulations containing 1–2% ZnO showed better physical homogeneity. Further optimization is therefore required to improve physical stability while maintaining photoprotective performance.