Optimization of superheated steam extraction of essential oil from Citrus limetta Peel by response surface methodology

Citrus essential oil (EO) is well known for its antimicrobial, antioxidant, and aromatic properties, making it valuable in medicine, cosmetics, and the food industry. In this study, response surface methodology (RSM) with central composite design (CCD) was applied to optimize the experimental conditions for maximum recovery of EO from Citrus limetta peel by superheated steam extraction. The factors analyzed included flow rate (40–80 mL/min), extraction temperature (120–160 °C), and extraction time (30–60 min). The optimal EO yield of 0.31 % (w/w) was achieved at 60.69 mL/min, 140.05 °C, and 45.79 mins. Superheated steam extraction (SHSE) produced significantly more EO than traditional hydro-distillation (HD) and steam distillation in a shorter period of time. The model's significance was validated using an analysis of variance (ANOVA), and the regression model showed a strong quadratic correlation (R² = 0.97), making it suitable for predictions. GC–MS analysis revealed that the EO extracted through SHSE contained the highest number of chemical constituents, with monoterpenes, particularly d-limonene, as the major component. The future goal is to establish SHSE as a standard method for EO extraction, offering superior efficiency, reduced environmental impact, and higher quality products for the food, medicine, and cosmetics industries.