目的 针对甘薯鲜切后易氧化褐变问题，研究超声处理对鲜切甘薯酶促褐变影响的机制，确定最佳的超声处理时间。方法 甘薯经鲜切后，先在25 ℃，40 kHz下超声处理不同时间（0，5，10，20 min），然后测定其在4 ℃冷藏期间对甘薯色泽、丙二醛（MDA）含量、褐变相关酶活性及酚类底物含量的影响。结果 适宜时间的超声处理能有效保持鲜切甘薯的亮度和色度，抑制MDA的积累，钝化多酚氧化酶（PPO）和过氧化物酶（POD）的活性，激发苯丙氨酸解氨酶（PAL）活性，提高了甘薯总酚含量和抗氧化能力，延缓了褐变的发生。结论 以超声处理10 min的防褐变效果最佳，处理20 min会对甘薯组织造成损伤，从而加重褐变。

The work aims to study the physiological mechanism of ultrasonic treatment on enzymatic browning in view of the oxidative browning of fresh-cut sweet potato and find the optimal ultrasonic treatment time. Fresh-cut sweet potato slices were treated with ultrasound for 0, 5, 10 and 20 min at frequency of 40 kHz and temperature of 25 ℃. The color, malondialdehyde content, browning related enzyme activities and total phenol content of fresh-cut sweet potato at 4 ℃ storage were tested. Moderate ultrasonic time effectively maintained the brightness and color of fresh-cut sweet potato, inhibited the accumulation of malondialdehyde, passivated the activity of polyphenol oxidase and peroxidase, stimulated the activity of phenylalanine ammonia-lyase, improved the total phenol content and antioxidant capacity, and ultimately delayed browning of fresh-cut sweet potato. The best anti-browning effect is achieved by ultrasonic treatment for 10 min, and ultrasonic treatment for 20 min will cause damage to sweet potato tissue and aggravate browning.