Effect of ultrasonic treatment on water-soluble pectin and degrading enzymes in cell wall of persimmon fruit during storage

The effect of ultrasonic treatment (25 kHz, 400 W, 20 degrees C, 20 min) on water-soluble pectin (WSP) content and structure, and degrading enzymes in cell wall of persimmon fruit during storage was studied. Results indicated that after storage for 15 d, the firmness of ultrasonic-treated persimmon fruit increased by 22.43 %, and the activity of pectin degrading enzymes PG, PME, and PL decreased by 34.32 %, 8.52 %, and 17.27 % compared with the control, respectively. Additionally, ultrasonic had little effect on the WSP content, but could slightly inhibit the decrease of WSP molecular weight and branched-chain, thus delaying the degradation of WSP. By inhibiting the activity of pectin degrading enzyme, ultrasonic slowed the depolymerization of the WSP structure and maintained the stability of cell wall structure, thus improving the firmness of persimmon fruit. The results will provide a reference for revealing the mechanism of ultrasonic on fruit softening.