Abstract

The sorption isotherms of Aloe vera were determined at 8, 30 and 45 °C, for a range of water activity (0.10-0.95). Modeling of the isotherms was done using the GAB, BET, Oswin, Halsey, Henderson, Smith, Caurie and Iglesias-Chirife equations. The fit quality of the models on experimental data was evaluated using the determination coefficient, sum squared errors and chi-square statisticals. The statistical results showed that the best fit quality was obtained by the Iglesias-Chirife model, followed by the GAB and Halsey. Monolayer moisture contents were obtained between 0.05-0.19 g water/g d.m. In addition, these parameters were temperature-dependent according to an Arrhenius-type equation. The sorption heat was calculated using the Clausius-Clapeyron equation giving 133.40 kJ•mol^-1 (desorption) and 49.60 kJ•mol^-1 (adsorption) at a moisture content of 0.01 g water/g d.m. The experimental heat data showed a good fit quality when these were evaluated by the Tsami equation.

Submitted: June 27, 2007 · Accepted: April 28, 2008 · Published: June 17, 2008

Recommended Citation

Uribe, Elsa; Miranda, Margarita; Lemus, Roberto; and Vega-Gálvez, Antonio (2008) "Moisture Adsorption and Desorption Isotherms of Aloe Vera (Aloe Barbadensis Miller) and Determination of Sorption Heats," International Journal of Food Engineering: Vol. 4 : Iss. 4, Article 12.
DOI: 10.2202/1556-3758.1262
Available at: http://www.bepress.com/ijfe/vol4/iss4/art12