title: Blueberry polyphenol oxidase: Characterization and the kinetics of thermal and high pressure activation and inactivation.
abstract: Partially purified blueberry polyphenol oxidase (PPO) in Mcllvaine buffer (pH=3.6, typical pH of blueberry juice) was subjected to processing at isothermal-isobaric conditions at temperatures from 30 to 80 °C and pressure from 0.1 to 700 MPa. High pressure processing at 30-50 °C at all pressures studied caused irreversible PPO activity increase with a maximum of 6.1 fold increase at 500 MPa and 30 °C. Treatments at mild pressure-mild temperature conditions (0.1-400 MPa, 60 °C) also caused up to 3 fold PPO activity increase. Initial activity increase followed by a decrease occurred at relatively high pressure-mild temperature (400-600 MPa, 60 °C) and mild pressure-high temperature (0.1-400 MPa, 70-80 °C) combinations. At temperatures higher than 76 °C, monotonic decrease in PPO activity occurred at 0.1 MPa and pressures higher than 500 MPa. The activation/inactivation kinetics of the enzyme was successfully modelled assuming consecutive reactions in series with activation followed by inactivation.
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Rd, Melbourne, VIC 3030, Australia. Electronic address: netsanet.shiferawterefe@csiro.au.
authors.forename: Netsanet Shiferaw
authors.initials: NS
authors.lastname: Terefe
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Rd, Melbourne, VIC 3030, Australia.
authors.forename: Antoine
authors.initials: A
authors.lastname: Delon
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Rd, Melbourne, VIC 3030, Australia.
authors.forename: Roman
authors.initials: R
authors.lastname: Buckow
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Rd, Melbourne, VIC 3030, Australia.
authors.forename: Cornelis
authors.initials: C
authors.lastname: Versteeg
mesh_terms: D029798:Blueberry Plants / Q000201:enzymology*; D004156:Catechol Oxidase / Q000378:metabolism*; D004789:Enzyme Activation; D005638:Fruit / Q000201:enzymology*; D006358:Hot Temperature; D007700:Kinetics; D011312:Pressure; D013696:Temperature
chemical_list: D004156:Catechol Oxidase
keywords: Activation kinetics; Blueberry; High pressure processing; Inactivation kinetics; PPO; Polyphenol oxidase; Thermal processing