Effects of PEF and heat pasteurization on PME activity in orange juice with regard to a new inactivation kinetic model

AĞÇAM E., AKYILDIZ A., Evrendilek G. A.

FOOD CHEMISTRY, cilt.165, ss.70-76, 2014 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 165
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1016/j.foodchem.2014.05.097
  • Dergi Adı: FOOD CHEMISTRY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.70-76
  • Anahtar Kelimeler: Pulsed electric fields (PEF), Pectin methyl esterase (PME), Orange juice, Inactivation kinetics, Shelf-life, PULSED ELECTRIC-FIELDS, COMMERCIAL ENZYME PREPARATION, HIGH HYDROSTATIC-PRESSURE, PECTIN METHYL ESTERASE, QUALITY PARAMETERS, SUBLETHAL INJURY, CITRUS JUICES, CARROT JUICE, METHYLESTERASE, PECTINESTERASE
  • Çukurova Üniversitesi Adresli: Evet

Özet

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 mu s) and HP (90 degrees C-20 s) 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 (587.8-2375.4 s(-1)), and the time required for a 90% reduction (D-e, 3917.7-969.5 s). Quantification of the increase in PEF energy to ensure a ten-fold reduction in D-e (z(e), 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. (C) 2014 Published by Elsevier Ltd.

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 thePEF (25.26 kV/cm-1206.2 mu s) and HP (90 degrees C-20 s) 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 (587.8-2375.4 s(-1)), and the time required for a 90% reduction (D-e, 3917.7-969.5 s). Quantification of the increase in PEF energy to ensure a ten-fold reduction in D-e (z(e), 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 oforange juice during storage.