Foam drying in the food industry

Foam‐drying foods is now an established unit operation in the food industry. The three basic foam drying variants, vacuum puff, foam‐mat and foam spray drying are reviewed. Where applicable, the process parameters are related to other drying methods and to generalized drying theory. The foam‐drying methods are described in relation to equipment, process parameters, type of food products, product characteristics and economics.