Thermal and High-Pressure Inactivation of Tomato Polygalacturonase: A Kinetic Study
نویسندگان
چکیده
Polygalacturonase (PG) was extracted from tomato fruit. The inactivation kinetics of the PG crude extract was investigated under isothermal and isobaric-isothermal conditions. Thermal inactivation of tomato PG in the temperature range 58 to 65 8C could be described by a fractional conversion model, and in the temperature range from 70 to 90 8C by a biphasic model. Pressure-temperature inactivation (range 300 to 600 MPa/5 to 50 8C) of tomato PG could be described by a fractional conversion model, which points to first-order inactivation kinetics of a pressure-sensitive enzyme fraction and to the occurrence of a pressure-stable PG fraction. A mathematical model describing the influence of pressure and temperature on the inactivation rate constant was formulated.
منابع مشابه
Thermal and high-pressure stability of purified polygalacturonase and pectinmethylesterase from four different tomato processing varieties
Polygalacturonase (PG) and pectinmethylesterase (PME) were extracted and purified from four tomato varieties (Galeón, Malpica, Perfectpeel and Soto) used in the processing industry. The processing stability (thermal and high pressure) of PG and PME from the four varieties was analyzed, and they all showed the same behavior. PG was present in two isoforms, PG1 (inactivated at 90 C, 5 min) and PG...
متن کاملPurified tomato polygalacturonase activity during thermal and high-pressure treatment.
Extracted tomato polygalacturonase was purified by cation-exchange chromatography (and gel filtration) and characterized for molar mass, isoelectric point, as well as optimal pH for polygalacturonase activity. The enzymatic reaction of purified tomato polygalacturonase on polygalacturonic acid as substrate was investigated during a combined high-pressure/temperature treatment in a temperature r...
متن کاملThermal inactivation of pectin methylesterase, polygalacturonase, and peroxidase in tomato juice.
Thermal inactivation kinetics have been determined for pectin methylesterase (PME), polygalacturonase (PG), and peroxidase (POD) in tomato juice. Two parameters, the inactivation rate constant (k) at a reference temperature and the activation energy for inactivation (E(a)), were determined for each enzyme. For PME and PG, the k and E(a) values reported here do not agree with those in several pr...
متن کاملKinetic parameters for the thermal inactivation of quality-related enzymes in carrots and potatoes.
Kinetic parameters for the thermal inactivation of several enzymes in carrot and potato homogenates have been determined. In carrots the most heat-resistant activity was polygalacturonase, followed by peroxidase and pectinmethylesterase. In potatoes peroxidase was the most resistant, followed by pectin methylesterase, polyphenol oxidase, and lipoxygenase. There were several notable similarities...
متن کاملPolygalacturonase, pectinesterase, and lipoxygenase activities in high-pressure-processed diced tomatoes.
High-pressure processing (HPP) can inactivate pathogenic microorganisms and degradative enzymes without the use of heat, thereby minimizing the destruction of flavors, nutrients, and other quality attributes. Lipoxygenase plays a role in the off-flavor production of tomatoes, whereas pectinesterase and polygalacturonase impact tomato texture. The purpose of this study was to determine HPP's abi...
متن کامل