Carbohydrates of different origins and forms are found in most food products. Generally speaking, the more carbohydrate, the more difficult becomes the drying process, as carbohydrates, if dried from a non-crystallized feed, are thermoplastic and hygroscopic. Carbohydrates will reduce the viscosity of the concentrate.
One large group of carbohydrates is lactose, which is found only in milk and by-products from milk processing, for example in whey from cheese production. The advantage of lactose from a drying point of view is that it can be precrystallized if found in a supersaturated solution (high solids, low temperature). The sticking point temperature is increased by precrystallization, and drying becomes easier.
Sucrose is used in food products as a sweetener, and also to add calories in e.g. baby foods and other powdered beverages. If the final sucrose content in a product must be larger than what is possible to incorporate in liquid form in the concentrate to be dried, it is possible to add it in dry form into the spray dryer during the drying of the liquid feed and thus obtain a blended, agglomerated, homogeneous final product.
Fructose as found in all fruits is very thermoplastic and hygroscopic. Products like fruits therefore cannot be spray dried unless a filler is used as carrier, skim milk solids or maltodextrine, for example.
Maltodextrine is another carbohydrate, which is frequently used as a filler, carrier, or sweetener. With a DE of 10-40 it can be used in many food products, as it is easy to dry.
Carbohydrates are excellent as binding material, and agglomerated products can easily be produced, if the spray drying plant is designed for this purpose.