Iron-Catalyzed Oxidation of (+)-Catechin in Model Systems

Autoxidation of (+)-catechin in wine-like model solutions containing 0−20 mg L-1 of ferrous iron was monitored by HPLC with diode array detection. The rate of catechin oxidation and the extent of browning increased with the iron level. Some of the oxidation products were formed in larger amounts at higher iron concentrations. These included colorless compounds and yellow pigments with absorbance maxima between 440 and 460 nm. The iron-catalyzed reactions leading to these compounds competed with iron-independent reactions generating different products which are presumably identical to those formed in enzymically oxidized catechin solutions. Keywords: (+)-Catechin; autoxidation; ferrous ions; CLHP; browning