Inhibition of potato polyphenol oxidase by Maillard reaction product

The inhibitory effect of MRP (Maillard reaction product) on potato polyphenol oxidase (PPO) was investigated. As the reaction time of glucose/glycine was increased at 90 °C, the inhibitory effect of the produced MRP toward potato PPO was increased, whereas the amounts of glycine and glucose were decreased. The MRP synthesized from arginine, cysteine, histidine and lysine significantly inhibited potato PPO. The MRP prepared from glucose and glycine inhibited potato PPO non-competitively. The MRPs synthesised from monosaccharides, such as fructose and glucose, and glycine were more inhibitory against potato PPO than those from disaccharides. The MRP formed by increasing glucose and glycine concentration exhibited a stronger inhibitory effect on potato PPO. The MRP formed from glucose and glycine showed strong inhibition toward potato PPO with (+)catechin, catechol, 4-methylcatechol and l-DOPA as substrates among tested polyphenols.