The food industry is constantly challenged to produce high-quality products with a long shelf life. Vacuum and freeze belt dryers are key technologies in this process. These systems enable the gentle and efficient drying of sensitive foods, while at the same time preserving their valuable nutrients.
Vacuum and freeze belt dryers combine the advantages of belt and vacuum drying. The mostly liquid and pre-concentrated product is conveyed on a belt through a vacuum chamber, where it passes through various heating zones. As soon as the product enters the dryer, a kind of flash evaporation takes place due to the vacuum inside the dryer. The product slightly foams, forming a porous structure, and almost all of the water evaporates. At the end of the drying process, the dry product leaves the dryer through a rotary valve for further processing.
Advantages of vacuum drying
By reducing the air pressure using vacuum pumps in the dryer, the product can be gently dried at low temperatures. This protects and preserves temperature-sensitive ingredients. Vacuum freeze belt drying is technically similar to vacuum belt drying. But with one important difference: In freeze drying, the vacuum level is kept so low that the water in the product sublimates — going directly from the ice phase to the vapor phase. Compared to vacuum belt drying, this keeps the product temperature even lower and the drying process more gentle.
Both vacuum and freeze belt dryers are used in a wide range of applications in the food industry. In short, wherever liquids need to be dried quickly and efficiently, yet gently, to preserve their ingredients. One example is the drying of fruit and vegetable purees or juices into powders for use in smoothies, instant soups and baby foods. Vacuum belt dryers are also used in the production of herb and spice powders that must retain their intense flavors and colors.