OPTIMIZATION OF ESSENTIAL OIL EXTRACTION FROM KINNOW (CITRUS RETICULATA BLANCO) PEEL: A RESPONSE SURFACE METHODOLOGY APPROACH INTEGRATING ULTRASONIC AND OHMIC HEATING PRETREATMENTS

Kinnow peel, a rich source of essential oil (EO), holds significant potential for applications in the food and pharmaceutical industries due to its aromatic and bioactive properties. However, the efficient extraction of EO from kinnow peel remains a challenge, necessitating the exploration of innovative extraction techniques. This study aimed to investigate the impact of two pretreatment methods-ultrasonic-assisted extraction (USAE) and Ohmic heating-aided extraction-on the extraction kinetics and chemical composition of kinnow peel EO using hydrodistillation (HD). Ultrasonic extraction parameters (power, time) and Ohmic heating variables (voltage, temperature, and salt concentration) were optimized using response surface methodology to achieve maximum yield. The results indicated that USAE produced higher EO yields (0.8% to 2.40%) compared to Ohmic heating (0.8% to 2.25%). The optimal conditions for USAE were 225.94 W, a solvent ratio of 692.23 mL, and 24.05 minutes, yielding a predicted 2.338% EO with a desirability of 0.961. For Ohmic heating, the best results were achieved with 219.02 V, 1.45% salt concentration, and 75.60°C, yielding 2.302% EO with a desirability of 1.000. These findings highlight that ultrasonic pretreatment provides superior extraction efficiency for essential oil (EO) without altering its natural composition, making it a promising method for industrial applications.