What is wet mixing?
Different dry ingeredients may be mixed/blended in dry form to a homegeneous mix in a rotating drum or similar. However, some of the ingredients may be available only in liquid form like milk and vegetable oil. In some cases- even if all the ingredients to be mixed are in powderform- it is prefered to dissolve all the products in water, i.e. wet mixing to start from a liquid mix before further processing. A liquid mix can be pasterized and the final bacteria content can then be controlled.
What is it used for?
Wet mixing is today used extensively in Infant Formulae production, Coffee Whitener, and production of imitation milk, where skim milk powder is mixed with water and vegetable oil for the production of imitation whole milk powder.
What does GEA Niro supply?
In a complete processing line supplied by the GEA Group of companies, the wet mixing part is typically engineered and supplied by
GEA Liquid Processing. The heart of the wet mixing is done in the vacuum mixer, where all the ingredients are mixed under vacuum to avoid air in the concentrate. The final mix is then
homogenized in two stages before final heat treatment,
evaporation and
drying.
Example of a wet mix procedure
The wet mixing system is normally divided into a water-soluble part and an oil soluble part. The preparation can be continuous or batch-wise. The water-soluble part is done by addition of powders into milk or water in a high shear vacuum mixer to limit air in the concentrate. The mix can be circulated over a tank. Powder and hot water are continuously added to the vacuum tank, until the total batch volume has been achieved.
Click here to download the pdf of the Turbo Mixer.
After dissolving of all the dry ingredients, the water soluble minerals are added. Oil soluble vitamins are normally dissolved in oil in a small separate tank and then added to the oil mix tank. The pre-heated oils from oil mix tanks are then added into the product mix followed by pasteurization and homogenization, cooling and storage. At this stage of the process the quality of the product is checked.
The plant is designed in a way making corrective actions possible, before resources are used for concentration and drying. In the case of continuous processing, all components (solids, fat, proteins, minerals) are added in line and adjustments are continuous to reach and maintain the correct product composition.