title: Effect of Phloroglucinol and Resorcinol on the Clingstone Peach Polyphenol Oxidase-catalyzed Oxidation of 4-Methylcatechol.
abstract: Phloroglucinol and resorcinol are not substrates for clingstone peach (Prunus persica) polyphenol oxidase, but they react with 4-methyl-o-quinone, produced either enzymatically or nonenzymatically, to give an intense red or red-brown color with a maximal absorption at about 470 nanometers. Several colored products were isolated from an ethyl acetate extract of the reaction by two-dimensional thin layer chromatography. Based on thin layer chromatographic and spectral studies of the enzymatic and nonenzymatic reactions, polyphenol oxidase does not play a role in the reaction between 4-methyl-o-quinone and phloroglucinol, resorcinol, d-catechin, or orcinol. In such reactions, the function of polyphenol oxidase is the formation of 4-methyl-o-quinone which then reacts nonenzymatically with the above phenols. Activation energies of both enzymatic and nonenzymatic reactions were determined.
authors.affiliation: Department of Food Science and Technology, University of California, Davis, California 95616.
authors.forename: T C
authors.initials: TC
authors.lastname: Wong
authors.forename: B S
authors.initials: BS
authors.lastname: Luh
authors.forename: J R
authors.initials: JR
authors.lastname: Whitaker