Response Surface Optimization of Citronella Oil Encapsulation using Gum Arabic as Biopesticide

The use of chemical pesticides negatively impacts the environment, health, and ecosystems, necessitating safer alternatives such as biopesticides. This study aimed to determine the effects and optimal conditions of pH, temperature, and coating-to-oil ratio on the distribution and encapsulation size result. Encapsulation was done by dissolving, gum Arabic as coating agent in water and mixed at 50 °C. This solution was then combined with citronella oil and vigorously mixed. pH and temperature of the solution were adjusted to form microdroplets. Finally, a crosslinking agent was added to solidify the droplets, and they were further processed to remove air bubbles. Response Surface Methodology was employed to optimize the distribution and encapsulation size, resulting optimum conditions were achieved at pH 5, coating to oil ratio of 1.159:1 (gum arabic to essential oil, g/g), and a temperature of 55 °C. Efficacy tests revealed that citronella oil biopesticide killed 77.85% of Spodoptera exigua pests on day 3, compared to 55.85% in the control group without biopesticide. This study demonstrates the potential of citronella oil biopesticide as an alternative to chemical pesticides. HIGHLIGHTS The study successfully optimized the encapsulation process of citronella oil-based biopesticides using response surface methodology (RSM). Optimal conditions were determined at pH 5, temperature 55 °C, and a coating-to-oil ratio of 1:1.591 g/g, achieving a uniform particle size. The encapsulated biopesticide effectively controlled Spodoptera litura, reaching 80% mortality by day 4 and 100% by day 7. The optimized formulation yielded a PI of 0.39 and a Z-Average particle size of 417.35 nm, ensuring enhanced stability and efficacy. GRAPHICAL ABSTRACT