Say cheese!

Say cheese!

What do you get if you mix vinegar and milk?

What you need:

  • Milk - it works best with full fat or semi-skimmed
  • Vinegar
  • Glass
  • Kitchen towel

How to:

1. Pour milk into the glass until its around 1/4 full.

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2. Add 2-3 tablespoons of vinegar to the glass. Stir. What can you see?

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3. Place a piece of kitchen towel on top of a second glass. Slowly pour the mixture through the kitchen paper. You should be left with a white, plastic-y looking substance in the kitchen towel and the liquid in the other glass. You might need a few pieces of kitchen towel to get rid of all the liquid.

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What does the white solid look like? Can you squeeze it together and get rid of more of the liquid? Don't eat it - it won't taste very nice!

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Experiment with milk that contains different amounts of fat. What happens? What do those mixtures look like?

What's happening:

You've made cheese! Although the stuff you make won't taste very nice, you've created cheese in a similar way to commercial cheese makers.

Milk contains a protein called casein, which is negatively charged. Vinegar contains hydrogen ions, which are positively charged. The hydrogen ions and casein proteins attract each other and form the white, plastic-y lumps. The lumps are called curds and the process of forming the lumps is called curdling. The liquid is called whey.

Cheese makers don't normally use vinegar to curdle milk - they normally add an enzyme called rennet, which causes the milk to separate into curds and whey.

What cheese did your mixture look like? It should look a little bit like cottage cheese. Cottage cheese is just the curds sieved from the whey. Other cheeses, like cheddar, are pressed for a long time to remove more of the liquid. Some cheeses, like smelly Stilton, have bacteria or fungi added to them whilst they age, which gives them a different flavour.

To find out more about using bacteria and fungi in cheese, go to Mighty Microbes.