Preparing red cabbage indicator

The juice of red cabbage contains a natural pH indicator that changes colour according to the acidity of the solution. 
Red cabbage contains a pigment called flavin which is also found in apple skins, plums and grapes.
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Very acidic solutions turn anthocyanin into a red colour. 
Neutral solutions will result in a purplish colour. 
Basic solutions turn into in greenish-yellow.
The pH of a solution can be determined based on the colour that it turns the anthocyanin pigments in red cabbage juice.

Making red cabbage indicator:

1. Chop up red cabbage and place in a blender.
2. Add water to the blender and blitz.
3. Sieve the mixture over a jug and collect the red cabbage juice.
4. Use this to acid to your various different acidic/basic solutions to determine their pH.