How To Extract Protein Casein From Milk

Casein is the primary protein component in cow's milk.

Image Credit: Ciaran Griffin/Stockbyte/Getty Images Casein is a protein that makes up approximately 80 percent of the total protein content of cow’s milk. Existing as globules within the milk and largely responsible for giving milk its white color, casein precipitates out of solution when heated and then exposed to acid. A simple acetic acid solution, in the form of white distilled vinegar, works well to extract casein from reconstituted nonfat powdered milk. The precipitated casein forms an elastic white material that you can remove from the liquid within milk.

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Step 1

Combine 50 g of powdered nonfat milk and 1 pint of distilled water in a heat-resistant glass container.

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Step 2

Heat the mixture to 105 degrees F. Monitor the temperature using an electronic thermometer.

Step 3

Add the vinegar slowly to the milk mixture. Stir the mixture gently with the plastic spatula. Continue to add vinegar and stir the mixture until the casein begins to precipitate from the liquid in small blobs of white solid matter.

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Step 4

Press any precipitated casein to the side of the glass container with the plastic spatula, allowing the liquid to drain to the side of the container.

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Step 5

Collect the casein with the spatula and transfer it to another container. Continue to add vinegar and remove precipitated casein until no more casein forms.

Step 6

Pour off any liquid that may have separated from the casein in the other plastic container.

Things You'll Need

Powdered nonfat milk Distilled water White distilled vinegar Heat resistant glass container Plastic container Stove Electronic thermometer Plastic spatula

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  references
  
      Penn State University: Isolation of Casein, Lactose, and Albumin from Milk
    
      The Sunday Times: Can you make plastic out of milk and vinegar?
    
      University of California: Preparation of Casein from Skim Milk
       




  references
  
      Penn State University: Isolation of Casein, Lactose, and Albumin from Milk
    
      The Sunday Times: Can you make plastic out of milk and vinegar?
    
      University of California: Preparation of Casein from Skim Milk
    




Casein is the primary protein component in cow's milk.

Image Credit: Ciaran Griffin/Stockbyte/Getty Images

Powdered nonfat milk
Distilled water
White distilled vinegar
Heat resistant glass container
Plastic container
Stove
Electronic thermometer

Plastic spatula

   Penn State University: Isolation of Casein, Lactose, and Albumin from Milk

   The Sunday Times: Can you make plastic out of milk and vinegar?

   University of California: Preparation of Casein from Skim Milk