Development of a new method for fast measurement of water sorption isotherms in the high humidity range Validation on gelatine gel Original Research Article

A fast and accurate method has been set up to measure sorption isotherms of solid foods in the water activity range 0.9–1. In a purpose-built device thin slices of the studied material are submitted to an air flow of very high velocity (more than 10 m s−1), at any temperature between 4°C and 40°C. Air relative humidity is controlled by a reduction in pressure of a saturated air. This method was validated over the range 0.7–0.9 using gelatine gel samples by comparison with the standard saturated salt method. Results obtained at two temperatures (3.5°C, 20°C) and three values of pH (4, 5.2 and 8) were used to test the ability of different fitting models.