Researchers have developed a cost effective process to reduce the viscosity of milk and milk products while increasing their solids content through the use of micro and nano-bubbles.
Viscosity is the measurement of a fluid’s internal resistance to flow. It is the main physical property of milk and milk products that limits their ability to be processed. A small change in concentration creates a rapid change in viscosity. Viscosity limits the increase in concentration of milk and milk products. Therefore, a reduction of viscosity allows for a higher concentrated milk and milk product.
This novel concept involves incorporating air bubbles in the size range of 200 nanometer – 40 micrometer into milk, condensed milk, or yogurt. After the bubbles are introduced into the substance, the viscosity is drastically reduced. A reduced viscosity means a higher concentration can be obtained. For example, skim milk is concentrated in an evaporator under vacuum to approximately 50% total solids when producing milk powder. The concentrated skim milk is then dried using a spray dryer. It is difficult to concentrate the skim milk further because of the limitations of the milk’s viscosity. Incorporating the bubbles into the skim milk, reduces the viscosity, and thereby allows an increase in the total solids above 50% in the evaporator. By creating a higher concentration and a lower viscosity the production costs associated with the processing of powdered milk and other milk products can be reduced.
Another way viscosity affects the dairy industry is through the use of membrane filtration. Membrane filtration is typically used for concentration and standardization of milk proteins to produce value-added products, such as milk protein concentrate and milk protein isolate. However, as the concentration increases so does the retentate viscosity resulting in decreased processed efficiency. Building on the use of nano and micro bubbles to reduce viscosity, researchers at Kansas State University injected the bubbles into the milk prior to going through the membrane filtration process. The bubbles controlled the viscosity in the ultrafiltration process and resulted in a whey protein concentration that is double what it would have been without the injection of the bubbles. The bubbles allow for better removal of non-protein components from milk systems.
The use of micro and nano bubbles also has an affect on the preparation of milk protein powder through the spray drying of a liquid dairy product. The introduction of the bubbles creates a powder material that has more beneficial solubility characteristics and with the reduced viscosity also improves the performance and efficiency of the spray-drying unit.
- No chemical additives are needed; physical treatment, no labeling issues
- Simple, cost effective process to implement in existing milk production plants
- Reduces the cost of production of milk and milk products
- High protein dairy powder
- Yogurt products
- Other liquid products where viscosity is an issue