Separating Milk

Denaturing Milk

Although we are not sure what Carver taught his students that first year, we can guess that because he had spent a great deal of time studying the dairy industry and products in Iowa, that this could have been a part of the curriculum. Tuskegee had been a farm and there were milk cows, so he may have started with some simple work with milk. Additional background information can be found at the bottom of this page.

Materials Required

• Stove, pan and graduate cylinder

• Small container for holding liquid

• 50 ml of milk (non fat is best, but any will work)

• 5 ml vinegar

• Lighter or matches 

Procedure

1) Pour about 50 ml of milk into your clean pan. (Use your new graduated cylinder for this purpose.)

2) Heat the milk gently over your candle heating stove until it is just warm. (100 degrees F if you have a thermometer. If not, test the milk temperature as one would test milk from a baby’s bottle--on the wrist)

3) When the milk is warm, add 5 ml of vinegar. Stir. Note the reaction--the curds and whey are forming and separating.

4) Carefully separate the liquid whey from the clabbered (white curdled) milk by straining it through a filter. Cheesecloth or a paper filter made from paper towels can be used. Fold the paper towel to make a filter as shown below:

5) The liquid that drips through the filter is whey.  The curds stay in the filter.  Save the curds in a separate cup.

Question: Describe the properties of the curds. What do they look like?

Discussion

Curds are the part of milk that is the protein and fat.  The curds are used to make cheese and cottage cheese.  The whey is the the liquid portion of milk that contains the sugars and some smaller proteins.  It can be used to make ricotta cheese or whey protein supplements.

We can use our curds and whey in several experiments! 

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