Smart optimization of Caulerpa–moringa biodegradable coatings via response surface methodology using a central composite design approach

Coatings made from biopolymers sourced from marine and plant materials have arisen as sustainable substitutes for synthetic packaging, tackling both postharvest preservation and environmental issues. This research improved a bioactive coating solution composed of crude Caulerpa lentillifera extract, crude Moringa oleifera leaf extract, and glycerol as a plasticizer, employing Response Surface Methodology (RSM) with a Central Composite Design (CCD). The independent variables included crude Caulerpa concentration 3–5% w/v, crude Moringa extract proportion 0.07–0.15% v/v, and glycerol concentration 0.5–1.0% v/v, while the pH and Opacity serve as response variable. The quadratic model for pH was statistically significant (p < 0.0001), accounting for 99.77% of the variation (R²), with significant synergistic and non-linear interactions among the variables. Optimal pH stability was attained at moderate concentrations of all components, ensuring compatibility with fruit surfaces. For opacity, crude Caulerpa concentration had the strongest effect (F = 176.94, p < 0.0001), followed by glycerol (p = 0.0155), with minimal influence from crude Moringa extract within the tested range. The optimized formulation achieved stable pH and enhanced opacity, improving UV–Vis shielding performance. Overall, the findings highlight the potential of polysaccharide-rich crude Caulerpa extract combined with crude Moringa bioactives to produce functional, environmentally sustainable coatings that reduce reliance on synthetic packaging and support greener food preservation practices.