Sorption and thermodynamic properties of cork from the 35°C and 50°C isotherms

Because of its characteristics, cork currently has no substitute in the bottle stopper industry for high quality wines and champagnes. Few studies have been conducted on water-cork interactions, and especially on the thermodynamic behaviour of cork. The hygroscopic and thermodynamic properties of two cork samples of the same quality, harvested in 1968 and 2006, were studied to determine any differences in behaviour over time. The 35°C and 50°C isotherms were plotted following the saturated salts method and fitted using the GAB model. The isotherms were compared by means of hysteresis coefficients. The infrared spectra were recorded to analyse chemical changes in the cell wall, and the thermodynamic parameters were determined using the integration method based on the Clausius- Clapeyron equation. No significant differences were observed between the equilibrium moisture content obtained in the two samples, although the monolayer saturation moisture content was significantly lower in the older cork. In both types of cork, as also occurs with wood, the points of inflexion where multilayer sorption begins to predominate over monolayer sorption occurred at very similar values, at around 31- 35% relative humidity (RH). In terms of thermodynamic properties, the net isosteric heat curves were similar to those obtained for wood, and the bond energy in the recently harvested cork was lower than in the older cork.

Bibliographic Details

Main Authors:	García Fernández, F., De Palacios, P., Esteban, L. G., García-Iruela, A., González-Adrados, J. R., López Álvarez, J. V.
Format:	artículo biblioteca
Language:	English
Published:	Centre de Cooperation Internationale en Recherche Agronomique Pour le Developpement 2012
Subjects:	Cork, Desorption, Hygroscopicity, Isotherm, Isosteric heat, Sorption, Thermodynamics,
Online Access:	http://hdl.handle.net/20.500.12792/1559 http://hdl.handle.net/10261/292177
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