It doesn’t just happen when you eat one. That just speeds up the process.

“Bananas left outside will begin to turn brown within a few days. This occurs because bananas contain an enzyme called polyphenol oxidase that reacts with oxygen and coats the banana with a sort of rust that accounts for the dark brown color.”

Source

@marinelife beat me to the punch. Just remember that, even though we need it to live, oxygen is a corrosive gas.

Yup. Same thing happens to sliced apples.

I too eat bananas. Let’s assume there are two equal bananas sitting on my kitchen counter with just the right number of freckles (432 ). If I peel one and eat it, the peel will be black in an hour or two while the one on the counter will have 435 freckles. In fact I put the peel in my burnable trash bag where it ends up heating my house for a short while. I don’t know why the peeled peel turns black faster unless it is oxygen getting at it from two sides instead of one. One thing I am sure about – the second banana will be gone in a coupe of hours.

There’s considerable evidence that the polyphenol oxidase reaction is a defense mechanism that boosts the plant’s resistance to insects and infection when some injury has occurred. The poor banana is, in effect, scrambling its defensive forces to protect itself in response to your heartless attack.

@thorninmud Putting it out of its misery is the least I can do.

@worriedguy Just make it quick

Bananas they grow in the tropical equator, so don’t put your bananas in the…refridg-er-ator!