How does a bannana rot?

Answer 1

When a banana decomposes it creates ethylene oxide, amylase, and protease gasses. If kept in a bag the gasses can not escape and will cause the fruit to age rapidly. If on the counter it will age more on the bottom first, where the gasses are more isolated. The best way to keep bananas from aging is to hang them over the counter on a fruit stand of some sort.

NOTE: If you have unripe fruit, you can set it in a bowl with a bunch of bananas and it will ripen faster.