Why do apples go brown, and why aren’t the oceans warmer?

We explore some of the curious questions that science can answer

The brown fruit can be una-peel-ing but is perfectly safe to eat (Getty/iStockphoto)

Why do apples go brown?

When you cut an apple you’re actually bursting open the cells that make up the apple. This releases an enzyme called phenoloxidase. This enzyme takes oxygen from the air and adds it to a chemical in the apples called tannin.

When oxygen and tannin are bound together, the tannin turns brown. Cooking or chilling the apple will stop it from turning brown. Vitamin C also stops apples from turning brown because it grabs the oxygen from the air before it can react with the tannin.