Comparison of β-Cyclodextrin Effect on Polyphenol Oxidation Catalyzed by Purified Polyphenol Oxidase from Different Sources

Abstract

The effects of β-cyclodextrin (β-CD) on polyphenol oxidation catalyzed by apple polyphenol oxidase (PPO), endive PPO, or mushroom tyrosinase have been compared. β-CD forms a complex with phenolic substrates of PPO by inclusion. Assuming a 1:1 β-CD/phenol stoichiometry, and assuming that PPO is inactive on the complex β-CD/phenol, KD values were similar when determined kinetically by inhibition of apple PPO or endive PPO. However, the experimental velocities found during inhibition of mushroom tyrosinase by β-CD were higher than the values predicted by this model. In this latter case, it was assumed that mushroom tyrosinase is able to act on the complex β-CD/phenol. A new model based on this assumption allows experimental and calculated velocities to be fit in presence of β-CD. Keywords: Enzymatic browning; polyphenol oxidase; apple; endive; mushroom; inhibition; cyclodextrin