Rainbow carrots?

I bought a pack of carrots the other week which claimed to be 'rainbow carrots'.  They were certainly more colourful than the usual orange carrots, with yellow and purple ones in the pack, but they fell somewhat short of a rainbow which my boys will tell you has red, orange, yellow, green, blue and (depending which boy you ask!) purple/indigo and violet.  I decided that we could try a little science experiment to try and make more of the rainbow...

'Rainbow' carrots

I cooked the colours separately as when we last had some of these carrots a year or so ago, the purple stained the other colours and they all ended up purple!  Both boys, despite being quite suspicious of new foods, happily ate the separately cooked purple (which were slightly orange in the middle) and yellow carrots alongside the orange ones.

Cooked carrots

I thought it was likely that the purple colour came from anthocyanins which are also found in red cabbage and are pH-sensitive. To test this, and try and make more of the rainbow, we soaked a piece of the purple carrot in each of these solutions during dinner:

1. Vinegar - acidic

2. Bicarbonate of soda solution - alkaline

3. Kitchen cleaner - very alkaline and I wouldn't recommend as you need to keep away from little fingers and eyes and it didn't change the colour more than the bicarbonate of soda.

After soaking for about 5 minutes, we took the carrot slices out and arranged them on a plate in colour order. We had a convincing red (well, more pink but close enough!), the original orange and yellow, then two greeny-blue (soaked in alkaline solutions) and the original purple. Not a perfect rainbow but closer to a rainbow than the original three colours!

Almost a rainbow

I realised that we could have some more fun with the purple carrot cooking liquid as a (slightly less smelly) version red cabbage cooking liquid, but I will save that for another post over the weekend.  I might look for some seeds to grow our own purple carrots next year as they were happily eaten which is an improvement on red cabbage which the boys both turn their noses up at despite enjoying its colour-changing abilities!