When apples are cut, the exposed fruit underneath the skin react with the oxygen in the air, which causes the apple slices to turn brown. This experiment explores how the apple slices react when coated with different liquids, like milk, lemon juice, vinegar, or water. You’ll discover lemon juice is one of the liquids that work best. That’s because lemon juice has a compound that reacts with oxygen before the oxygen reacts with the apple. It’s also acidic, which slows down the browning reaction (and also makes it taste sour!). A light spritz of lemon juice will keep your apples fresh without altering their taste too much.
- ¼ cup water
- ¼ cup lemon juice
- ¼ cup vinegar
- ¼ cup milk
- Cutting board
- Permanent marker (soft, felt-tipped)
- 1 Gather your materials.
- 2 On four Ziploc® brand sandwich bags, write the name of the liquid you’re going to test. Label a fifth bag “nothing” for your control bag. This bag will contain apples with no liquid. That way, you’ll be able to see the difference between a normal apple and the other apples that have been soaked!
- 3 Pour the water, lemon juice, vinegar, and milk in separate bags. Make sure to match each liquid to its label.
- 4 Cut the apple into slices. (This part should only be done by an adult.)
- 5 Place two apple slices in each bag. Seal the bag and lightly shake it so the liquid coats the apple slices. Let them soak for two or three minutes.
- 6 Pour any excess liquid out of the bags. Reseal them and check on the apples every 10 to 15 minutes to see what happens. Which ones turn brown? Which ones stay fresh?