Teatime Experiment: Green Eggs
By Mark Steer
Red cabbage is funny stuff, not least because most of time it’s purple. However, it has some curious colour-changing properties that you can use to your advantage for a colourful Christmas teatime.What to do
- Get some raw red cabbage that never quite made the lunch table and boil it up for about twenty minutes.
- Squeeze the juice from the cabbage.
- Start to gently fry an egg.
- Once the egg is just beginning to turn opaque, sprinkle the cabbage juice over the egg white. It will turn green. Honestly.
What happened
Red cabbage contains a natural indicator of acids and alkalis – a bit like litmus. Pigments in the plants tissues called anthocyanins turn red in acid and green in alkaline solutions. Since the white of an egg is slightly alkaline, the chemicals will turn a lurid green. This is also why pickled cabbage is red since vinegar is acidic. In neutral conditions the pigments are purple, hence their colour in the vegetable patch.
Anthocyanins are also found in plums, grapes and apple skins (think about it… ah yes, fruits which can come in a range of colours). They are also the chemicals which cause hydrangea flowers to be different colours dependent upon the acidity of the soil in which they’re growing.
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This experiment has been adapted from Mick O'Hare's excellent book How to Fossilise your Hamster see more at www.newscientist.com/hamster.
How about trying one of our other top tens:
This experiment has been adapted from Mick O'Hare's excellent book How to Fossilise your Hamster see more at www.newscientist.com/hamster.
How about trying one of our other top tens:
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- Top Ten Geek Holidays
- Top Ten Stupid Science Studies
- Top Ten Work-related Ills
- Top Ten Killer Vegetables
- Top Ten Weird Drinks
- Top Ten Grim Parasites
- Top Ten Things Science Hasn't Explained
Hub image: Michiel Pruijssers
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