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Sorption Isotherms of Granny Smith Apples Hot-Air Dried and Texturized by "Controlled Sudden Decompression to the Vacuum".

Authors :
Iguedjtal, Tarik
Louka, Nicolas
Allaf, Karim
Source :
International Journal of Food Engineering. 2007, Vol. 3 Issue 5, p1-20. 20p. 1 Black and White Photograph, 2 Diagrams, 4 Charts, 6 Graphs.
Publication Year :
2007

Abstract

Moisture sorption isotherms of Granny Smith apples hot-air dried and texturized by Controlled Sudden Decompression (D´ etente Instantann´ee Contr¿ol´ ´ee DIC) were determined and compared using a gravimetric method. The DIC has been developed to confer a porous structure to partially dehydrated foods by expanding them and facilitating the drying process at lower water content. The samples were stored in a chamber; the relative humidity is controlled by an atomizing humidifier at 20, 30 and 40_C, and relative humidities ranging from 10% to 90%. The sorption capacity decreased with increasing temperature at a given water activity. The hysteresis effect was not significant for both of the dried and texturized apples. The experimental sorption data were fitted to 8 various isotherm models including two parameter relationships (BET, Halsey, Smith, Henderson, Oswin), three parameter equations (Ferro-Fontan, GAB) and four parameter equations (Peleg). A non-linear least square regression software was used to evaluate the model's constants. The goodness of fit of each isotherm was quantified through the mean relative percentage deviation modulus E. The Ferro-Fontan, Peleg, GAB and Oswin equations were best for characterizing the sorption behaviour of Granny Smith apples for a whole range of temperatures and water activities studied. The surface area corresponding to the monolayer was determined for the texturized apples and compared to the dried samples. The results showed that the treatment by DIC increases the surface area of apples. For understanding the water properties and calculating the energy requirements phenomena, net isosteric heat was evaluated by the applying Clausius-Clapeyron equation. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
15563758
Volume :
3
Issue :
5
Database :
Academic Search Index
Journal :
International Journal of Food Engineering
Publication Type :
Academic Journal
Accession number :
27473470
Full Text :
https://doi.org/10.2202/1556-3758.1151