Superheated steam extraction and RSM-based optimization of antioxidant activity in Citrus paradisi essential oil and evaluation of antimicrobial activity

In this study, response surface methodology (RSM) based on central composite design (CCD) was employed to optimize the antioxidant activity of Citrus paradisi peel essential oil (CPEO) extracted by superheated steam extraction (SHSE). The process parameters temperature (140-160 °C), time (40-80 min), and flow rate (40-80 mL/min) were evaluated. The maximum antioxidant activities, including DPPH-FRSA (95.98%), FRAP (203.87 mg/100 g), and H₂O₂ scavenging (91.38%), were observed at optimum extraction conditions of 150 °C temperature, 60 min time, and 60 mL/min flow rate. Antimicrobial activity results showed that SHSE-extracted essential oil (EO) had better activity compared to hydro-distillation (HD) and steam-distillation (SD). GC-MS analysis revealed that d-limonene, β-pinene, β-myrcene, and trans-carveol were the main components, and their higher concentration in SHSE EOs enhanced their antioxidant and antimicrobial activities. The results indicated that SHSE is an environmentally friendly and effective technique for valorizing Citrus peel waste into high-value bioactive EO. In the future, CPEO may be explored for the development of cost-effective antimicrobial films and pharmaceutical formulations, requiring further compatibility and safety evaluations.