Polyphenoloxidase deactivation kinetics during ohmic heating of grape juice
Makaleler > Tam Makale · 2008
Yazarlar: Filiz İÇİER, Hasan YILDIZ, Taner BAYSAL
JOURNAL OF FOOD ENGINEERING, SCI Expanded İndekslerine Giren Dergi, Uluslararası, 2008, cilt 85, ss 410-417
DOI: 10.1016/j.jfoodeng.2007.08.002
Özet
The heating method affects the temperature distribution inside a food, and directly modifies the time-temperature relationship for enzyme deactivation. Fresh grape juice was ohmically heated at different voltage gradients (20, 30, and 40 V/cm) from 20 degrees C to temperatures of 60, 70, 80 or 90 degrees C and the change in the activity of polyphenoloxidase enzyme (PPO) was measured. The critical deactivation temperatures were found to be 60 degrees C or lower for 40 V/cm, and 70 degrees C for 20 and 30 V/cm. Various kinetic models for the deactivation of PPO by ohmic heating at 30 V/cm were fitted to the experimental data. The simplest kinetic model involving one step first-order deactivation was better than more complex models. The activation energy of the PPO deactivation for the temperature range of 70-90 degrees C was found to be 83.5 kJ/mol. (c) 2007 Elsevier Ltd. All rights reserved.