What exactly makes bananas go brown?

Question

I know that often oxidation processes are mentioned when referring to the color change from yellow to brown in bananas (specifically: those that you get everywhere in supermarkets, with no seeds).However, I am really interested if there is a specific oxidative pathway that is generally followed in this process, and whether it has been examined.

Answer 1

The original color of bananas is green due to chlorophyll pigments. When the fruit comes in contact with a ripening agent such as ethylene, the green chlorophyll pigments break down to phenol derivatives thus getting the yellow hue. As the fruit ripens further, more ethylene is produced by the fruit itself. Unlike other fruits that produce tiny amounts of ethylene, bananas produce large amounts of ethylene. These induce a polyphenol oxidase (PPO) enzyme pathway that reduces phenol derivatives in a multi-step process to melanin which is the brown compound.