Freeze Drying

Abstract

Freeze drying is a well-known dehydration process in the food and dairy industry. Compared to other drying techniques such as spray drying or drum drying, freeze drying is an expensive process due to its relatively high investment, operation and maintenance costs. However, the quality of the final dried product in terms of rigid structure with reduced shrinkage, high rehydration ability and superior quality render this method suitable for production of products with high market value. The major applications of freeze drying in the dairy industry are preservation of probiotics and starter cultures. Apart from these, freeze drying is also suitable for production of freeze dried milk, cheese, lactose, cream and ice-cream for usage in the baking industry, restaurants and the biotechnology industry. Freeze-dried dairy products also have prospects as space, military and emergency foods. This chapter provides a detailed description about the stages of freeze drying, the heat- and mass-transfer mechanism and the properties influencing the freeze drying of dairy products. In addition, special emphasis is given to the use of freeze drying as a microencapsulation technique for the protection and delivery of probiotics.