This work aimed to study the effect of different inhibitors i.e. ascorbic acid, cysteine and citric acid and some amino acids i.e. glycine, valine, methionine and phenylalanine on inhibition of polyphenol oxidase (PPO) activity mainly responsible for browning process in fresh-cut fruits and vegetables. Also identifying the mechanisms of each inhibitor under various conditions. The results confirmed that ascorbic acid and cysteine act as competitive PPO inhibitor at low concentrations (0.84-7.15mM) and react at high concentrations ( 1.5% ) in the assay solution with the resulted quinone to...