Effect of the Drying Method on the Water Sorption of Dehydrated Apple and Potato

SUMMARY —The method of drying apple and potato affects primarily the rate of sorption of water of the dehydrated product, and to a lesser degree the equilibrium isotherms. The freeze‐dried products adsorbed more water vapor than the puff‐dried and air‐dried materials. The apparent diffusivity of water vapor was considerably higher in the freeze‐dried samples than in the air‐dried materials. In puff‐dried samples, the diffusivity had an intermediate value. The diffusivity in freeze‐dried apple and potato decreased at higher relative humidities, and the effect was opposite in air‐dried samples.