Desorption is the release of molecules that a material had previously adsorbed or absorbed, the reverse of sorption. Moisture sorption isotherms measured during drying quantify how water leaves the product. The concept matters for flavour release, since aromas desorb from the food matrix during chewing, and for packaging, where contaminants can migrate into foods in storage. An oxygen adsorption-desorption cycle has even been observed in dough during breadmaking. In laboratories, thermal desorption frees trapped volatiles for analysis. Packaging designers use desorption data to predict how long barrier properties will truly last.