Effects of Ultrasonic Treatment on the Quality and Related Enzyme Activities of Sweet Persimmon after Post-harvest

In order to study the effect of ultrasonic treatment on the storage period of post-harvest persimmon fruit, with "Youhou" sweet persimmon as the test material, the changes of hardness, color, water content, soluble solids content (SSC), titratable acid (TA), pectin composition andrelated enzyme activity, total calcium content of the persimmon fruit after ultrasonic treatment (420 W, 30 min) for 0, 5, 10, 15, 20 d storage at （20±2）℃ and 85%~90% relative humidity were measured. The results showed that compared with the control group, the hardness, total color difference (∆E) and calcium ion content of the ultrasonic treatment group increased by 2.97 kg/cm², 3.31 and 22.28 mg/kg, respectively, but the polygalacturonase (PG) activity decreased by 8.79 μg/(min·g). Ultrasonic treatment can maintain high hardness, brightness and SSC of persimmon fruit, delay the decrease of fruit water content and total calcium ion content, and inhibit the increase of pectin degrading enzyme activity, thereby effectively delaying the softening of persimmon fruit, maintaining fruit quality and prolonging the storage period of persimmon fruit.