Pigments are molecules that contain colour and the ones in red cabbage juice ( anthocyanin ) are pretty special. By adding a base or acid, we can both change their shape and their colour! The pigments are easy to collect and the basis for two easy home experiments: Colour Changing Magic Potions and Making Litmus Paper.
- 1/2 red cabbage
- Hot water
- A food processor (or a big pot)
- Fine colander or flour sieve
- Shred or coarsely chop the red cabbage.
- You can then choose whether to boil or blend. I chose blending and it’s meant to result in slightly better colour.
- Boil: Pop in a pot with enough water to cover the cabbage and boil for 15 minutes.
- Blend: Pop in a food processor with about 3 cups of boiling / hot water. Blend until the cabbage is finely processed and then leave to soak for 15 minutes.
- Allow the cabbage mixture to cool and then strain the juice into a bowl. Tip: The juice will stain so glass is great if you have it. I used a flour sieve to strain mine into a glass pyrex jug.
You now have the cabbage juice you need for your two science experiments!
You can also freeze leftover juice in ice cube trays to make all natural coloured icing for birthday cakes or cupcakes!