Abstract:The study investigated the effect of ultrasound-assisted oxalic acid treatment on the color preservation and freshness of fresh-cut apples during storage. Fresh-cut apples were placed in a 0.5% oxalic acid solution and treated with ultrasound （300 W， 40 kHz） for 3 min. The changes in browning index （BI）， apparent color， peroxidase （POD） activity， polyphenol oxidase （PPO） activity， phenylalanine ammonialyase （PAL）activity， antioxidant capacity and total phenol content were investigated to systematically evaluate the color preservation and freshness effect of the ultrasound-assisted oxalic acid treatment on fresh-cut apples. The results showed that compared to the control group， the BI value， PPO and POD activity of the fresh-cut apples in the experimental group were significantly reduced during the storage period （0-8 d）， while the total phenolic content significantly increased at 2-8 d of storage （P<0.05）. The PAL activity of the experimental group was significantly lower than that of the control group on days 2 and 8 of storage （P<0.05）. Except for day 4 of storage， the antioxidant capacity of fresh-cut apples in the experimental group was significantly higher than that in the control group （P<0.05）. Therefore， ultrasound-assisted oxalic acid treatment can delay enzymatic browning by inhibiting the activities of PPO， POD， and PAL， and by enhancing the antioxidant capacity of fresh-cut apples， thereby achieving the goal of color preservation and freshness.