Have you ever wished you could make magic color-changing potions like Harry Potter? Well, now you can with one magical vegetable—cabbage. We’ve likely all turned up our nose at this vegetable in our food. It’s the star ingredient in dishes from coleslaw to sauerkraut and kimchi to cabbage rolls. In fact, cabbage was one of the first plants cultivated by humans beginning in Greece and Italy. Conquering Roman armies believed cabbage could cure wounds, so they took cabbage with them as medicine as they marched across Europe and Asia.
Wherever cabbage spread, people came up with legends and myths about the cabbage. Greeks believed that cabbages sprung from the tears of a king who killed his son. Scottish people believed that on Halloween a girl should pick the first cabbage she saw; the shape of its root would tell her what her future husband would look like. Germans said it was impolite to talk about cabbages while looking at the moon because the man in the moon was put there for stealing cabbage on Christmas Eve. Everyone believed that somehow or other cabbage was a magical plant.
And now you can try your own hand at cabbage magic. First, collect your materials: five see-through glasses, measuring spoons, some powder laundry detergent, baking soda, vinegar and most importantly—cabbage.
But you’ve got to make sure you get the right type of cabbage. There are hundreds of types of cabbage from the tall, Chinese bok choy to the tiny, little Brussels Sprout. Our potion calls for the red variety. Red cabbage is a tight, ball of purple leaves a bit smaller than a volleyball.
Take a few leaves and rip them up into pieces. Put them in a clear glass or plastic cup. Make sure its clear and colorless so you will be able see the magic. Fill the cup with water like you were pouring yourself a drink. If you leave this cup for a while the water will start to turn purple as the cabbage juice seeps into the water.
But if you’re not feeling very patient and want to see something truly amazing, put the cup in the microwave for a couple minutes. Be careful; when it comes out the water will be very hot and purple. There are chemicals in the cabbage called anthocyanins that give red cabbage its purple color. When the water is heated, theses chemicals that make the cabbage purple are released into the water, turning the water purple. But if the water is purple what color is the cabbage? If you leave the cabbage to soak, after about an hour, you’ll see that the edges of your cabbage pieces turn a ghostly blue-grey as the anthocyanins sneak out into the water. If you left it all day long, you’d have ghost cabbage.
Now that you have your cabbage juice, pour a half-cup of water into each of the other four cups. Into the first cup, mix two tablespoons vinegar. To the next one, add ½ tablespoon baking soda. Put a tablespoon of powder laundry detergent in the third. Make sure you wash the spoon in between each measurement! Leave the last glass as a control. The control will show you what the mixture would look like if you just added the cabbage solution to regular water, so you can get a good scientific comparison. Mix the solutions until the additions are mostly dissolved.
Add two tablespoons cabbage juice to each cup. You will notice that each one changes a different color. Wow, you’re a real wizard! Want to know how we did it? It goes back to the real potion masters of the world, chemists. Remember how I told you there was a chemical called anthocyanins in the cabbage that made it purple? Well, this chemical changes color based on the pH of a solution.
What’s pH? Nearly every solution is either acidic or basic. The pH scale goes from close to 0 up to 14 and we use it to explain how acidic or basic something is. Distilled, perfectly pure, water would fall at 7 on the pH scale, meaning it is neutral, neither acid nor base. If a solution’s pH is less than 7, it is acidic; the lower the number is the more acidic it is. However, if a number is higher than 7 it’s a base; the higher it is the more basic it is.
Believe it or not, you have acids and bases all around you. Every time you wash you hands, you’re using a base. You can tell soap is a base, because like most basic solutions, it’s slippery. Acids on the other hand can be identified by a sour taste; lemon juice is a great example of an acid. Can you think of other acids or bases?
Our cabbage solution starts close to neutral. The laundry soap is slippery and it changes our solution to green, so bases make our cabbage solution green! Vinegar is a solution of water and a chemical called acetic acid—that’s right it’s an acid. So will it make our solution green? No, the vinegar mixture turns pink.
Now are you ready for the real magic? Take the cup containing the baking soda solution. It should be a blue color, showing that it’s slightly basic. Add your pink vinegar solution. Watch out! It fizzes and turns purple. The acidic vinegar and basic baking soda have canceled each other out and we’re back at neutral.Try adding the green solution. What do you think will happen? That’s right the whole thing turns blue-green because it’s basic again.
Don’t you wonder what other things in your house are acids and bases? What is milk? What about apple juice? Grab your witch’s hat and cabbage head and try your hand at some colorful brews.