Elucidating the inhibitory mechanism on polyphenol oxidase from mushroom and melanosis formation by slightly acid electrolysed water

It has been revealed that slightly acid electrolysed water (SAEW) could delay enzymatic browning and melanin formation in food. In this work, multi-spectroscopic methods and UHPLC-Q-TOF-MS were combined to study the underlying reason. The reversible mixed-type inhibition mode of HOCl (main components in SAEW) was determined. The ground state complex formation quenched the intrinsic fluorescence of polyphenol oxidase (PPO) and it was stable at lower temperature. The PPO conformational change (transformation from alpha-helix to beta-sheet) induced by SAEW was confirmed by 3D fluorescence and Circular dichroism (CD) spectrum. Moreover, the driving force of the interaction between HOCl and PPO was hydrogen bond, which was validated by the molecular docking result. Besides, the formation of melanin related compounds including dihydrox-yphenylalanine (DOPA), dopaquinone, dopachrome, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), 5,6-dihy-droxyindole (DHI), and 5,6-indolequinone were significantly inhibited by SAEW treatment. These results demonstrated the potential of SAEW as a PPO inhibitor in the food industry.

Automated summary

It has been discovered that slightly acid electrolysed water (SAEW) can delay enzymatic browning and melanin formation in food. Through various spectroscopic methods, it was determined that SAEW inhibits PPO through a reversible mixed-type inhibition mode of HOCl as the main component. The interaction between HOCl and PPO was driven by hydrogen bonds.