Inhibition kinetics of catechin and ferulic acid on polyphenoloxidase from cephalothorax of Pacific white shrimp (Litopenaeus vannamei)

► Catechin showed mixed type reversible inhibition. ► Ferulic acid exhibited non-competitive reversible inhibition. ► Catechin and ferulic acid could chelate copper ion and hamper intermediate browning products. Inhibition kinetics and mode of catechin and ferulic acid towards polyphenoloxidase (PPO) from cephalothorax of Pacific white shrimp were investigated. Catechin or ferulic acid inhibited quinone formation catalysed by PPO in a dose dependent manner. Catechin showed mixed type reversible inhibition with Ki value of 1.4mM, whereas ferulic acid exhibited non-competitive reversible inhibition with Ki value of 37mM. With increasing concentrations, both catechin and ferulic acid had higher copper (Cu2+) reduction and copper chelating capacity (P