Foam Mat Drying of Food Materials: A Review

Foam mat drying is an economical alternative to drum, spray and freeze‐drying for the production of food powders. The liquid is whipped to form stable foam, and dehydrated by thermal means. The larger surface area of the foam accelerated the drying process for the rapid moisture removal from the high moisture feed. A high‐quality food powder can be obtained by the proper selection of foaming method, foaming agents, foam stabilizers, time taken for foaming, suitable drying method and temperature. In this article, the basics of foam and its structure, methods of foaming, types of foaming method and stabilizing agents for the production of stable foam have been analyzed. The influence of foaming agents and foaming properties on the drying characteristics of fruit juices are also studied. This article reviewed the application of foam drying process for different food materials, the microstructure and the quality of powders obtained by using different foaming agents. PRACTICAL APPLICATION: The renewed foam mat drying is considerably cheaper than freeze and spray drying for the production of fruit powders. This process can be used for large‐scale production of fruit powders because of its suitability for all types of juices, rapid drying at lower temperature, retention of nutritional quality, easy reconstitution and cost‐effective for producing easily reconstitutable juice powders. Fruit juice powders obtained through this process have high economic potentials over their liquid counterparts such as reduced volume or weight, reduced storage space, simpler handling and transportation, and much longer shelf life. The fruit powders obtained through this method can find applications in snacks, beverages, ice creams, bakery products, as a starter for the preparation of instant foods, pastes, etc.