title: Combined effect of high hydrostatic pressure and mild heat treatments on pectin methylesterase (PME) inactivation in comminuted orange.
abstract: BACKGROUND
  Comminuted orange, a product obtained by grinding the juice and peel and used to formulate beverages, has a high pectin methylesterase (PME) activity; thus the inactivation of this enzyme is necessary to avoid quality losses related to cloud loss. The use of high hydrostatic pressure (HHP) and mild temperature allows inactivation of enzymes with minimal quality changes. This work aimed to evaluate the effect of pressure, mild temperature and time of treatment, including come-up and holding time, on the inactivation of PME in comminuted orange, and to apply kinetic and response surface models (RSM) to predict residual PME activity (A/A0 ).
  
  
  RESULTS
  During come-up time in treatments at 68 °C, the higher the pressure, the lower was the A/A0 obtained. At 550 MPa/68 °C/10 min the lowest residual activity value was obtained (15.6%). A/A0 was well adjusted to the RSM, and a first-order kinetic model was applied to describe the inactivation of PME. In general, the higher the pressure, the lower was the A/A0 reached, as the increasing values of k from 3.5 × 10(-2) to 55.5 × 10(-2) min(-1) indicated. Activation volume (Va ) values ranging from -9.2 to -17.7 cm(3) mol(-1) , and activation energies (Ea ) between 50.0 and 68.2 kJ mol(-1) were calculated.
  
  
  CONCLUSIONS
  550 MPa/68 °C/10 min, 350 MPa/68 °C/10 min and 450 MPa/56 °C/10 min treatments were satisfactory (∼84% inactivation) to inactivate PME. A first-order kinetic model was applied to describe PME inactivation, and the resulting A/A0 adjusted to the RSM. In addition, linearized Arrhenius and Eyring equations were well fitted in order to obtain Ea and Va , respectively.
authors.affiliation: Centro de Biotecnología FEMSA, Escuela de Biotecnología y Alimentos Tecnológico de Monterrey, CP 64849, Monterrey, NL, México.
authors.forename: Viridiana
authors.initials: V
authors.lastname: Tejada-Ortigoza
authors.affiliation: Centro de Biotecnología FEMSA, Escuela de Biotecnología y Alimentos Tecnológico de Monterrey, CP 64849, Monterrey, NL, México.
authors.forename: Zamantha
authors.initials: Z
authors.lastname: Escobedo-Avellaneda
authors.affiliation: Centro de Biotecnología FEMSA, Escuela de Biotecnología y Alimentos Tecnológico de Monterrey, CP 64849, Monterrey, NL, México.
authors.forename: Aurora
authors.initials: A
authors.lastname: Valdez-Fragoso
authors.affiliation: Centro de Biotecnología FEMSA, Escuela de Biotecnología y Alimentos Tecnológico de Monterrey, CP 64849, Monterrey, NL, México.
authors.forename: Hugo
authors.initials: H
authors.lastname: Mújica-Paz
authors.affiliation: Centro de Biotecnología FEMSA, Escuela de Biotecnología y Alimentos Tecnológico de Monterrey, CP 64849, Monterrey, NL, México.
authors.forename: Jorge
authors.initials: J
authors.lastname: Welti-Chanes
mesh_terms: D001628:Beverages; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D032084:Citrus sinensis; D005519:Food Preservation; D006358:Hot Temperature; D006801:Humans; D006874:Hydrostatic Pressure
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase
keywords: HHP; PME; comminuted orange; inactivation; kinetic parameters