Why doesn't the color of cut apples change when they are placed in salt water?
When peeled apples are left as they are, they quickly turn brown. This is because apples contain an enzyme that changes color by binding with oxygen in the air.
Therefore, to prevent color change, the surface of the peeled apple should not be exposed to oxygen. One way to do this is to soak the apples in salt water.
Once the apples are placed in salt water, a film of salt water is formed on the surface of the apples. This prevents the enzymes contained in the apples from combining with the oxygen in the air. This prevents the color of the apples from changing.
