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

• Published in: Journal of food engineering Vol. 85; no. 2; pp. 180 - 190
• Main Authors: Iguedjtal, T., Louka, N., Allaf, K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-03-2008; Elsevier
• 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; Potatoes; Surface area; Texturizing; Sorption isotherms; Isosteric heat; Drying; Vegetables; Surface; Sorption; Potato; Heat; Area; Tuber
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2007.06.028

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.