Effects of ultrasound on glass transition temperature of freeze-dried pear (Pyrus pyrifolia) using DMA thermal analysis
- Authors: Islam, Nahidul , Zhang, Min , Liu, Huihua , Xinfeng, Cheng
- Date: 2015
- Type: Text , Journal article
- Relation: Food and Bioproducts Processing Vol. 94, no. (2015), p. 229-238
- Full Text: false
- Reviewed:
- Description: The effect of ultrasound pretreatment at various power (360 W, 600 W and 960 W, frequency 20 kHz) on the glass transition temperature of freeze dried pear (Pyrus pyrifolia) has been studied. DMA temperature plots were divided into four sections (A - glassy region, B - transition region, C - Rubbery plateau region and D - terminal region) with the aim to analyze their properties changed with sonication. Under the same freeze drying condition, with the increase in ultrasonic power, dried pear showed higher glass transition in terms of storage modulus, loss modulus and loss tangent peak. Also a decrease in a
The inactivation kinetics of polyphenol oxidase in mushroom (Agaricus bisporus) during thermal and thermosonic treatments
- Authors: Cheng, X. , Zhang, Min , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Ultrasonics Sonochemistry Vol. 20, no. 2 (2013), p. 674-679
- Full Text: false
- Reviewed:
- Description: The effect of thermal and thermosonic treatments on the inactivation kinetics of polyphenol oxidase (PPO) in mushroom (Agaricus bisporus) was studied in 55-75°C temperature range. In both the processes, the inactivation kinetics of PPO followed a first-order kinetics (R2 = 0.941-0.989). The D values during thermal inactivation varied from 112 ± 8.4 min to 1.2 ± 0.07 min while they varied from 57.8 ± 6.1 min to 0.88 ± 0.05 min during thermosonic inactivation at the same temperature range. The activation energy during thermal inactivation was found to be 214 ± 17 kJ/mol, while it was 183 ± 32 kJ/mol during thermosonic inactivation. The inactivating effect of combined ultrasound and heat was found to synergistically enhance the inactivation kinetics of PPO. The D values of PPO decreased by 1.3-3 times during thermosonic inactivation compared to the D values of PPO during thermal inactivation at the temperature range. Therefore, thermosonication can be further developed as an alternative to "hot break" process of mushroom. © 2012 Elsevier B.V. All rights reserved.
- Description: 2003010582