title: Effects of PEF and heat pasteurization on PME activity in orange juice with regard to a new inactivation kinetic model.
abstract: The inactivation kinetics of pectin methyl esterase (PME) during the shelf life (4°C-180 days) of freshly squeezed orange juice samples processed by both pulsed electric fields (PEF) and heat pasteurization (HP) was evaluated in the study. The PME inactivation level after the PEF (25.26 kV/cm-1206.2 μs) and HP (90°C-20s) treatments were 93.8% and 95.2%, respectively. The PME activity of PEF-processed samples decreased or did not change, while that of HP samples increased during storage (p<0.01). A kinetic model was developed expressing PME inactivation as a function of the PEF treatment conditions, and this enabled the estimation of the reaction rate constant (587.8-2375.4s(-1)), and the time required for a 90% reduction (De, 3917.7-969.5s). Quantification of the increase in PEF energy to ensure a ten-fold reduction in De (ze, 63.7 J), activation electric fields (-921.2 kV cm(-1)mol(-1)), and electrical activation energy (12.9 kJ mol(-1)) was also carried out. Consequently, PEF processing was very effective for the inactivation of PME and for providing stability of orange juice during storage.
authors.affiliation: Department of Food Engineering, Faculty of Agriculture, Cukurova University, Balcali, Adana, Turkey. Electronic address: eagcam@cu.edu.tr.
authors.forename: E
authors.initials: E
authors.lastname: Agcam
authors.affiliation: Department of Food Engineering, Faculty of Agriculture, Cukurova University, Balcali, Adana, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: Akyıldız
authors.affiliation: Department of Food Engineering, Faculty of Engineering and Architecture, Abant Izzet Baysal University, Golkoy Campus, Bolu, Turkey.
authors.forename: G Akdemir
authors.initials: GA
authors.lastname: Evrendilek
mesh_terms: D001628:Beverages / Q000032:analysis*; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D032084:Citrus sinensis / Q000737:chemistry*; D005511:Food Handling; D006358:Hot Temperature; D061352:Pasteurization / Q000379:methods*
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase
keywords: Inactivation kinetics; Orange juice; Pectin methyl esterase (PME); Pulsed electric fields (PEF); Shelf-life