کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
225452 | 464495 | 2008 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Polyphenoloxidase deactivation kinetics during ohmic heating of grape juice Polyphenoloxidase deactivation kinetics during ohmic heating of grape juice](/preview/png/225452.png)
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 °C to temperatures of 60, 70, 80 or 90 °C and the change in the activity of polyphenoloxidase enzyme (PPO) was measured. The critical deactivation temperatures were found to be 60 °C or lower for 40 V/cm, and 70 °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 °C was found to be 83.5 kJ/mol.
Journal: Journal of Food Engineering - Volume 85, Issue 3, April 2008, Pages 410–417