title: Comparative study of the inactivation kinetics of pectinmethylesterase in tomato juice and purified form.
abstract: Pectinmethylesterase (PME) extracted from tomato fruit was purified by affinity chromatography. A single peak of PME activity was observed, presenting a molar mass of 33.6 kDa, an isoelectric point higher than 9.3, and an optimal temperature and pH for activity of 55 degrees C and 8.0, respectively. The processing stability of purified tomato PME in buffer solution was compared to PME stability in tomato juice. In both media, thermal inactivation of PME presented first-order inactivation kinetics, PME in tomato juice being more heat-labile than purified PME. Regarding high-pressure treatment, tomato PME showed to be very pressure-resistant, revealing an outspoken antagonistic effect of temperature and pressure. To avoid cloud loss in tomato juice, a time-temperature treatment of 1 min at 76.5 degrees C was calculated in order to have a residual PME activity of 1 x 10(-)(4) U/mL.
authors.affiliation: Pontificia Universidade Católica do Paraná, Brazil, and Laboratory of Food Technology, Department of Food and Microbial Technology, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium.
authors.forename: Diana
authors.initials: D
authors.lastname: Fachin
authors.forename: Ann M
authors.initials: AM
authors.lastname: Van Loey
authors.forename: Binh
authors.initials: B
authors.lastname: Ly Nguyen
authors.forename: Isabel
authors.initials: I
authors.lastname: Verlent
authors.forename: Indrawati
authors.initials: I
authors.lastname: Indrawati
authors.forename: Marc E
authors.initials: ME
authors.lastname: Hendrickx
mesh_terms: D001628:Beverages; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004795:Enzyme Stability; D005511:Food Handling; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018551:Solanum lycopersicum / Q000201:enzymology*; D011312:Pressure; D014783:Viscosity
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase