Ultrasound-assisted Vacuum Extraction of Polyphenols from Jujube Peel

In order to obtain maximum yield of polyphenols from jujube peel,ultrasound-assisted vacuum extraction( UAVE) was chosen to extract the peel of Ziziphus jujube var. Changzao. The effects of various conditions were investigated by single factor experiments and orthogonal design L9( 34). Based on the optimization condition,three extraction methods,i. e.,UAVE, ultrasound assist extraction( UAE) and conventional extraction( CE),were compared with both extraction time and polyphenols yield. To further evaluate UAVE,the radical scavenging activities( DPPH·) was measured,too. Results showed that: the optimal conditions were 50 % aqueous ethanol as extraction solvent,temperature 55 ℃,solid / liquid ratio 1 ∶ 30( g ∶ mL), ultrasonic power 240 W,extraction time 10 min. Under this condition,the polyphenols yield could be 5. 05 %,and the extraction rate could reach 97. 37 % with duplicate extraction. UAVE has advantages such as high yield and time saving by comparison with CE and UAE. The polyphenols extracted by UAVE showed that higher antioxidant activities could be obtained than those by CE and UAE. It indicated that UAVE could protect the bioactive capacity of polyphenols from jujube peel.