Combined effect of ultrasonic and oxyresveratrol on the browning and PPO of fresh‐cut potatoes

BACKGROUND Browning is a key problem in the process of fresh‐cut agricultural products. The present study investigates the synergistic inhibition of ultrasound (US) and oxyresveratrol (OXY) in the browning and polyphenol oxidase (PPO) of fresh‐cut potatoes. RESULTS US combined with OXY treatment significantly inhibited the browning of fresh‐cut potatoes and maintained better sensory quality in contrast to single treatment. PPO activity in the combined group was only 81% of control group after 96 h of storage. The combined treatment more effectively inhibited the increases of peroxidase and phenylalanine ammonia lyase activity, total phenols, chlorogenic acid, and caffeic acid, at the same time as enhancing 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging ability of fresh‐cut potatoes compared to single treatment. Moreover, the combined treatment induced irregular starch shape and promoted granule dissolution from potato tubers. In addition, the combined treatment decreased the fluorescence intensities of PPO and shifted the spectra peak from 341 to 335 nm depending on the treatment methods and processing sequence. The combined treatment could also destroy the hydrogen bond and secondary structure of PPO, leading to a decrease in α‐helix and random coil content. CONCLUSION The combined application of OXY at 0.06 mmol L −1 and US at 40 kHz (600 W) for 3 min is an effective way to control the browning of fresh‐cut potatoes and maintain the sensory quality. This study also provides a technical reference for controlling browning of fresh‐cut products based on US and chemical synergistic methods.