Exogenous isoleucine can confer browning resistance on fresh-cut potato by suppressing polyphenol oxidase activity and improving the antioxidant capacity

•Isoleucine (Ile) could significantly delay the browning of fresh-cut potato.•Ile treatment inhibited PPO activity partially by chelating Cu2+.•Ile treatment suppressed PPO activity by interacting with amino acid residues of PPO.•Ile treatment improved the antioxidant capacity of fresh potato. Fresh-cut potatoes are susceptible to enzymatic browning. In this study, the effect of isoleucine (Ile) on the browning of fresh-cut potatoes was evaluated, and the mechanism by which Ile influenced the browning was revealed. Results showed that exogenous Ile application could reduce the browning of fresh-cut potato chips. At 2–4 °C, control chips had lost saleability on day 1, while 1.0 % Ile treated chips were still acceptable on day 4. Ile alleviated the decrease of tyrosine, prevented the production of brown pigments, and inhibited the browning of potato mashes. The addition of Ile to potato mash decreased polyphenol oxidase (PPO) activity, which was partially recovered after adding copper acetate. Molecular docking showed that Ile could bind with the amino acid residues of PPO. Moreover, Ile treatment increased the activity of catalase (CAT) and peroxidase (POD), improved 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) inhibition rate, and decreased the malondialdehyde (MDA) content. This is the first research to demonstrate that Ile has potential to be used as a natural anti-browning agent and its mechanisms include decreasing PPO activity by chelating Cu2+ and interacting with the PPO amino acid residues, and improving the antioxidant capacity.