Asked by: Faye Lynch Williams (15 years old)
Cutting or dropping an apple causes compartments inside the cells, including the central storage sacs (vacuoles), to burst open, allowing chemicals to mix and oxygen to flood in and catalyse reactions.
In particular, chemicals in the vacuole called polyphenols come into contact with an enzyme called polyphenol oxidase, which is present in every cell in the apple. It’s this reaction that leads to the brown, unappetising ‘melanin’ chemicals that we see on a sliced or bruised apple.
Read more:
Subscribe to BBC Science Focus Magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.