Inhibitory effects of α-Na8SiW11CoO40 on tyrosinase and its application in controlling browning of fresh-cut apples

alpha-Na8SiM11CoO40 was synthesized and characterized. The inhibitory effects of alpha-Na8SiM11CoO40 on the activity of mushroom tyrosinase and the effects of alpha-Na8SiM11CoO40 on the browning of fresh-cut apples were studied. The Native-PAGE result showed that alpha-Na8SiM11CoO40 had a significant inhibitory effect on tyrosinase. Kinetic analyses showed that alpha-Na8SiM11CoO40 was an irreversible and competitive inhibitor. The inhibitor concentration leading to a 50% reduction in activity (IC50) was estimated to be 0.239 mM. Additionally, the results also showed that alpha-Na8SiW11CoO40 treatment could significantly decrease the browning process of apple slices and inhibit the polyphenol oxidase (PPO) activity. Moreover, application of alpha-Na8SiM11CoO40 resulted in higher peroxidase activity and promoted high amounts of phenolic compounds and ascorbic acid. This study may provide a promising method for the use of polyoxometalates to inhibit tyrosinase activity and control the browning of fresh-cut apples. (C) 2015 Elsevier Ltd. All rights reserved.