Subcritical water extraction of flavanones from defatted orange peel

Subcritical water extraction (SWE) is a green process that uses water as a solvent for extracting non-polar flavonoids by varying the temperature-dependent dielectric constant. Flavanones, including hesperidin and narirutin, constitute the majority of the flavonoids that occur naturally in citrus fruits. The effects of operating parameters temperature (110 -150 degrees C) and water flow rate (10 - 30 mL/min) on the SWE of flavonoids from defatted orange peel (DOP) were studied. The maximum yields of hesperidin (188.74 +/- 0.51 mg/g extract) and narirutin (21.98 +/- 1.39 mg/g extract) were obtained at 150 degrees C and 10 mL/min. These yields accounted for approximately 21% of the total amount of these flavanones in the extracts, leading to the purest extracts. SWE was compared with three conventional extraction methods and the results demonstrated that, compared to conventional extractions, SWE is a highly efficient method for the recovery bioactive compounds with high antioxidant activity.