Salicylic acid inhibits enzymatic browning of fresh-cut Chinese chestnut (Castanea mollissima) by competitively inhibiting polyphenol oxidase

The inhibitory effect and associated mechanisms of salicylic acid (SA) on the browning of fresh-cut Chinese chestnut were investigated. Shelled and sliced chestnuts were immersed in different concentrations of an SA solution, and the browning of the chestnut surface and interior were inhibited. The activities of polyphenol oxidase (PPO) and peroxidase (POD) extracted from chestnuts were measured in the presence and absence of SA. SA at concentrations higher than 0.3 g/L delayed chestnut browning by significantly inhibiting the PPO activity (P < 0.01), and the POD activity was not significantly affected (P > 0.05). The binding and inhibition modes of SA with PPO and POD, determined by AUTODOCK 4.2 and Lineweaver-Burk plots, respectively, established SA as a competitive inhibitor of PPO.