You slice an apple for snack time. You go to wash your hands… and when you come back, the white part has turned a sad brown colour! 😮
The apple is not dirty and it is not rotten. Something invisible changed it. Let's be science detectives and find out what!
An apple is made of millions of tiny boxes called cells. Each cell is like a little water balloon full of sweet juice.
Hidden in that juice are two secret things: a special helper called an enzyme, and tiny bits of food colour stuff. While the apple is whole and the cells are closed, they stay apart and nothing happens.
Tap the apple's cells to peek inside each one.
When the knife slices the apple, it breaks open those tiny cells. The juice spills out, and now the hidden enzyme and the colour stuff can finally touch each other.
But they still need one more guest to make brown… and that guest is floating all around us. Can you guess what it is? 💨
Which invisible thing in the air joins the reaction?
Oxygen from the air meets the enzyme and the colour stuff in the spilled juice. Together they make a new brown colour, a bit like rust on a bicycle. 🚲
Scientists call this reaction oxidation (say it: ox-i-DAY-shun). "Oxi" comes from oxygen!
Drag the slider to let more time pass. Watch the air slowly brown the apple.
If oxygen and the enzyme cause browning, we can fight back by blocking the oxygen or slowing the enzyme. Try each trick and see what happens!
Tap a trick to test it on the apple slice.
Lemon juice is full of vitamin C and is very sour (acidic). The sourness makes the enzyme too sleepy to work, and the vitamin C grabs the oxygen first — before it can reach the apple. Clever! 🦸
Match each helper to its job. Tap a job, then tap the helper that does it.
Now you know the secret, here are real tricks families in Singapore use. Tap each card to reveal why it works.
Tap all the cards to flip them over!
You discovered why apples turn brown. Here's everything you learned:
A brown apple is still safe to eat — it just changed colour. Now you can amaze your family with the science of snack time! 🌟