Sorption isotherms of potato slices dried and texturized by controlled sudden decompression

Controlled sudden decompression to a vacuum (DIC) was used to confer a porous structure to partially dehydrated foods by expanding them and facilitating the drying process at lower water content. Moisture sorption isotherms of Bintje potato slices hot-air dried and texturized by DIC were determined...

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Bibliographic Details
Published in:Journal of food engineering 2008-03, Vol.85 (2), p.180-190
Main Authors: Iguedjtal, T., Louka, N., Allaf, K.
Format: Article
Language:English
Subjects:
adsorption
Asymptotic properties
Biological and medical sciences
containers
controlled atmosphere storage
desorption
dried foods
Drying
drying temperature
Food engineering
Food industries
food preservation
food processing
Fruit and vegetable industries
Fundamental and applied biological sciences. Psychology
General aspects
Isosteric heat
Isotherms
Mathematical models
Moisture
Moisture content
Potatoes
Relative humidity
sampling
Sorption
Sorption isotherms
storage technology
Surface area
temperature
texturization
Texturizing
vacuum drying
water content
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Summary:Controlled sudden decompression to a vacuum (DIC) was used to confer a porous structure to partially dehydrated foods by expanding them and facilitating the drying process at lower water content. Moisture sorption isotherms of Bintje potato slices hot-air dried and texturized by DIC were determined and compared using a gravimetric method. The samples were stored in a temperature-controlled chamber at 20, 30 or 40 °C; and relative humidity was controlled between 5% and 90%. Both adsorption and desorption isotherms had a sigmoidal shape (type II). The sorption capacity decreased with increasing temperature at a given water activity. Hysteresis was more pronounced for texturized potatoes than for hot-air dried samples. Non-linear regression analysis was used to fit five moisture sorption isotherm models. The Peleg, Kats and Kutarov, GAB and BET ( a w less than 0.5) equations all accurately characterized the sorption behaviour. Texturizing by DIC increased the surface area of potato slices by ≈45% relative to heat air drying. The net isosteric heat of sorption was found to increase with decreasing moisture content and was higher for texturized potatoes than hot-air dried samples.
ISSN:0260-8774
1873-5770
DOI:10.1016/j.jfoodeng.2007.06.028