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Dry Blending

In the dry blending process, the ingredients are received from suppliers in a dehydrated powdered form and are mixed together to achieve a uniform blend of the macro and micro nutrients necessary for a complete infant formula product. Dry blending, including combined wet and dry processes, offers some manufacturing advantages over wet blending – spray drying. Dry blending is less capital intensive and more energy efficient than wet mixing – spray drying. Also, since dry blending does not involve the use of water in the manufacturing process, the processing line can be kept dry for long periods of time. In a dry environment, bacteria are denied the water needed to support growth. This reduces the chance that harmful bacteria will become established in the plant environment in sufficient numbers to cause product contamination. However, the microbiological quality of a dry-blended product is largely determined by the microbiological quality of the constituent dry ingredients. In a dry blending process, there is no heat treatment to destroy bacteria in the final product. Thus, if one or more ingredients in a dry-blended product are contaminated by even low numbers of harmful bacteria, these bacteria are likely to be present in the finished product.
  • The lack of water involved in the process makes it safer from a microbiological point of view, as no growth can be expected. However, the microbiological quality of the final dry mixed powder will be no better than what was used to form the 'mix'.
  • A much smaller investment, as less equipment and thereby, a smaller building is needed. The costs for energy and maintenance will also be considerably lower.


  • It does not allow incorporating lipids, which means that the ingredients should already contain them.
  • No heat treatment is included. Thereby the physical and microbiological quality is defined by the quality of the raw materials used, and how the actual dry mixing is performed.
  • Physical powder properties such as wettability and solubility will be defined by the properties of the single ingredients, unless a rewet agglomeration process follows the mixing and that adds to the investment and manufacturing costs.
  • The different ingredients have different densities and will therefore segregate during canning and transportation. In other words, the product can get an inhomogeneous appearance and composition, which can be vital for the end-user. 
The dry blending process begins with the receipt of the ingredients. The ingredients are typically stored until they are tested for conformance to specifications, including microbiological contamination. Since microbiological contaminants may be present in low numbers and may be non-randomly distributed within the lot, it is difficult to assure microbiological quality by lot testing alone. Therefore, manufacturers of dry-blended products try to develop and maintain close relationships with their ingredient suppliers. Each supplier must produce their product in a manner that assures that harmful bacteria will not contaminate the finished ingredient. This is usually accomplished by a combination of appropriate process controls and strict adherence to good manufacturing practices.

Dry ingredients are blended in large batches (1, 000 to 5,000 lbs.) in a ribbon blender or other large scale blending equipment. The ingredients must be blended until the nutrients are uniformly distributed throughout the batch. The blended product is then transferred directly to the powder packaging line. At the packaging line, the powder is transferred to a filler hopper that feeds powder into the can filling line. Filled cans are flushed with inert gas, seamed, labelled, coded and packed into cartons. Typically, finished product is held until it undergoes a final check for conformance to specifications, including testing for microbiological contaminants.


 Copyright © Ausnutrients 2011

Copyright Ausnutrients 2011