Abstract:The effect of walnut green peel polyphenol extract on the cell wall metabolism of Hami melon fruits during storage was studied. The fruits of the Hami melon variety ′Xizhoumi 25′ were treated with distilled water （control） or 30 mg/L walnut green peel polyphenol extract. Both groups were treated in corresponding liquid added with 0.5 mL/L Tween-20 for 20 min and then stored at room temperature [（22±2） ℃] with the relative humidity of （20±2）% for 18 d. The hardness， propectin content， soluble pectin content， and activities of enzymes related to cell wall metabolism of Hami melon fruits were measured every 3 d. The results showed that the treatment with 30 mg/L walnut green peel polyphenol extract inhibited the decreases in fruit hardness and propectin content and delayed the increases in soluble pectin content and activities of polygalacturonase（PG）（except for day 3）， cellulase （Cx）， and pectin methylesterase， β-glucosidase （except for day 3）， and β-galactosidase. The walnut green peel polyphenol extract could delay fruit softening and maintain fruit hardness by inhibiting the increases in the activities of enzymes related to cell wall metabolism in postharvest fruits of Hami melon.