Milk powder – made by spray drying

The ViscoScope® sensor is installed in a Varivent® corner housing in the supply line to the spray drier upstream of the pressure sprayer. This installation is free of dead space and meets all hygiene requirements.

Prozess

Milk powder is used in the production of yogurt, cheese, sweets and pastries, baby food etc. Milk contains about 88% water – this is reduced to approx. 40% by dehydration. In spray driers, the water content of the thickened milk is reduced to 2 - 3%.

Using a pressure sprayer (typically 50 - 250 bar), the milk is atomized and sprayed into a stream of hot gas (<250°C). Due to the enormous increase in its surface area, the milk evaporates in a fraction of a second and is dried to a fine powder.

For optimum spray drying, the droplets must have a precisely defined size. This is determined as a function of the milk used, the temperature and the viscosity of the thickened milk.

Throughout the spraying process, the ViscoScope® viscometer measures the viscosity and ensures that it is restricted within a narrow range. As the measurements are provided in real time, the system can respond quickly if the viscosity threatens to leave this range.

Between 6 and 7 liters of milk are required to make 1 kg of milk powder. The average price is approx. € 155 per tonne (in 2018).