Humidity Caking and Its Prevention

Humidity caking is a commonly encountered problem in a variety of dry food products, including granulated sugar and salt, instant beverages, dehydrated vegetables, and ground spices. The study of the caking phenomenon and its prevention by anticaking agents has a long history. Humidity caking usually occurs when a hygroscopic powder is exposed to moist air or wetted accidentally. Once a particle's surface is moistened, it can either be partially or completely dissolved or become sticky, which is a phenomenon associated with glass transition. The role of moisture contents in humidity caking of soluble crystalline powders at a constant temperature: the higher a powder's moisture contents or water activity the higher its tendency to cake. Storage results obtained at equilibrium conditions, still provide valuable insights into the agglomeration mechanisms and reveal the roles moisture, temperature, and conditioners play in caking and the efficacy of its prevention.