Enzymatic preparation and antioxidant activity of the phloridzin oxidation product

During apple processing, phloridzin, the main flavonoid in apples, can be oxidized to the yellow pigment, which contributes to the color of apple juice and ciders. However, there was no report about the bioactivities of this yellow pigment. In this study, the oxidation of phloridzin catalyzed by tyrosinase from mushroom was investigated. The main oxidation product with bright yellow color was purified and identified as the phloridzin oxidation product j (POPj) based on electrospray ionization mass spectrometry (ESI-MS) and C-13 nuclear magnetic resonance (C-13-NMR) spectroscopy. In the chemical and cellular system, POPj exhibited the higher peroxyl radical-scavenging activity than phloridzin. Our results suggested that POPj was a kind of potential food yellow pigment with antioxidant activity, which partly explained health-promoting functions of apple juices and ciders. Practical applicationsIn view of the potential toxicity of the artificial food yellow pigment, the need for natural and safe yellow pigment is increasing. In this study, the enzymatic preparation of the yellow pigment derived from phloridzin was investigated. Its antioxidant activity was first reported. This study can prompt the application of this new yellow pigment in food industry.