In my experience that banana is what ripens all other fruit that is remotely near it. That apple hasn’t got much time left before it suddenly is rotten
Hmm. I've always thought that bananas released the most ethylene; and that they can be used to ripen other fruit (or ripen themselves faster if you put them in a bag or something). ... But this seems to suggest it is apples that should be used for that - unless there's a significant difference between 'produced' and 'released'.
In any case, I guess it's something I might revisit and reassess.
Whoops, should have been https://en.wikipedia.org/wiki/1-Methylcyclopropene it blocks ethylene receptors that a bunch of plants use for regulating ripening and responding to stress conditions like drought, flooding, high salt, etc.