Calorimetric Techniques Applied to the Determination of Isosteric Heat of Desorption for Potato

Temperature had an influence on desorption isotherms of potato measured at six different temperatures (4, 14, 21, 28, 35 and 50°C). The parameters of the Oswin, Henderson, Halsey and GAB models, for isotherm representation, were identified. Water activity at any temperature could be calculated by means of only one equation using the GAB model, which gave the best fit to experimental data in all the range of water activity studied (0·4–0·9). Isosteric heats of water desorption of potato, were determined from the desorption isotherms following the Clausius–Clapeyron equation and from two thermal analysis techniques (DSC and TG). Similar results were obtained through the two methods, indicating that calorimetric techniques are adequate to obtain the isosteric heat of desorption of products with a high starch content. © 1997 SCI.