Green Egg Materials
- red (purple) cabbage
There are several ways you can prepare red cabbage juice for use as a pH indicator. Here's what I did:
- Coarsely chop about a half cup of red cabbage.
- Microwave the cabbage until it is soft. This took me about 4 minutes.
- Allow the cabbage to cool. You may wish to set it in a refrigerator to speed things up.
- Wrap the cabbage in a coffee filter or paper towel and squeeze the cabbage. Collect the juice in a cup.
- You can refrigerate or freeze leftover juice for later experiments.
- Spray a pan with cooking spray. Heat the pan over medium-high heat.
- Crack an egg and separate the egg white from the yolk. Set the yolk aside.
- In a small bowl, mix the egg white with a small amount of red cabbage juice. Did you see the color change? If you mix the egg white and red cabbage juice thoroughly then the 'white' of the fried egg will be uniformly green. If you only lightly mix the ingredients you will end up with a green egg that has white splotches. Yummy!
- Add the egg white mixture to the hot pan. Set the egg yolk in the middle of the egg. Fry it and eat it like you would any other egg.
The pigments in red cabbage are called anthocyanins. Anthocyanins change color in response to changes in acidity or pH. Red cabbage juice is purplish-red under acidic conditions, but changes to a blue-green color under alkaline conditions. Egg whites are alkaline (pH ~9) so when you mix the red cabbage juice into the egg white the pigment changes color. The pH does not change as the egg is cooked so the color is stable. It's also edible, so you can eat the fried green egg!