title: Partial characterization of polyphenol oxidase activity in raspberry fruits.
abstract: A partial characterization of polyphenol oxidase (PPO) activity in raspberry fruits is described. Two early cultivars harvested in May/June (Heritage and Autumm Bliss) and two late cultivars harvested in October-November (Ceva and Rubi) were analyzed for PPO activity. Stable and highly active PPO extracts were obtained using insoluble poly(vinylpyrrolidone) (PVP) and Triton X-100 in sodium phosphate, pH 7.0 buffer. Polyacrylamide gel electrophoresis of raspberry extracts under nondenaturing conditions resolved in one band (R(f)()(1) = 0.25). Raspberry PPO activity has pH optima of 8.0 and 5.5, both with catechol (0.1 M). Maximum activity was with D-catechin (catecholase activity), followed by p-coumaric acid (cresolase activity). Heritage raspberry also showed PPO activity toward 4-methylcatechol. Ceva and Autumm Bliss raspberries showed the higher PPO activity using catechol as substrate.
authors.affiliation: Plant Foods Science & Technology Department, Instituto del Frío (CSIC), Ciudad Universitaria, 28040-Madrid, Spain.
authors.forename: E M
authors.initials: EM
authors.lastname: González
authors.forename: B
authors.initials: B
authors.lastname: de Ancos
authors.forename: M P
authors.initials: MP
authors.lastname: Cano
mesh_terms: D004156:Catechol Oxidase / Q000737:chemistry* / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D005511:Food Handling; D005519:Food Preservation; D005638:Fruit / Q000201:enzymology*
chemical_list: D004156:Catechol Oxidase