Abstract: In the paper, the ultrasonic-assisted electrolyzed water extraction of pectin from pomegranate (Punica granatum L.) pomace was optimized, and the composition and structural characteristics of the pectin were analyzed. Using combination of one-factor-at-a-time method and Box-Behnken design, the optimal extraction conditions were obtained as follows: ultrasonic power density, 1 W/mL; pH, 1.7; extraction temperature, 60 ℃; extraction time, 33 min; and material to liquid ratio, 1:18 (g/mL). Under these conditions, the pectin yield was 14.95%, which increased by 2.2% compared with the ultrapure water extraction process, and the pectin extracted with electrolyzed water (EWP) had a lower molecular mass (7.294 × 106 g/mol) and higher galacturonic acid content (70.29%). Analysis by combined use of the chemical titration method and Fourier transform infrared (FTIR) spectroscopy indicated that EWP had a higher degree of esterification. It can be seen that the ultrasonic-assisted electrolyzed water extraction method is an efficient and environmentally friendly method. This research provides technical support for producing value-added products from pomegranate fruit and realizing efficient and comprehensive utilization of by-products.

Key words: pomegranate pomace, pectin, electrolyzed water, ultrasound