If you’ve ever played with natural food dyes, you might have already used red cabbage to make things the colour blue. Crazy, right?
Red cabbage has an abundance of pigments (which give it the pretty red colour) which are called anthocyanins. They dissolve well in water, and react to the pH balance–the acidity or basicity–of the water itself and anything that might be dissolved in it (the solution). In ordinary boiled water, which has a relatively neutral pH balance of around 7, anthocyanins are blue-violet.
When acidic substances are added, such as lemon juice or vinegar, the pH drops through a range of purple and to red, which would be a pH of 1 (very acidic). When a substance with a pH higher than 7 is added (a base, or alkaline substance), the colour ranges from green through to yellow and almost clear. Items that are base are considered the opposite of acids: they are items like washing soda, chalk and antacid medicines.
Who knew that cabbage could make such a rainbow of pretty colours?
Check out some science experiments to do with your kids here.
