I've seen a few times the suggestion to wrap the stems of bananas to prevent them from ripening. Yet at least one person who was espousing this admitted it was based on a misreading of a study:
I made an incorrect leap of imagination about ethylene production and abscission, the natural splitting of leaf or fruit from stem. I re-read the Sauter paper and realized that I got a little too inferency. I thought that since ethylene caused abscission, it would make sense to cover the point prone to abscission. I didn't test when I saw confirmations from Lifehacker and eHow. (I know! Those were my sources after all the research I'd done?! I'm embarrassed for me, too.)
Is there any actual science behind this technique? Or is it just an old wives' tale?
To clarify: The question here isn't whether ethylene gas ripens bananas, that's a well known fact. This question is solely about wrapping the stem to prevent the banana's own gas from ripening it.
Best Answer
Revised answer (old answer removed due to accidentally swerving off-topic and to some extent containing incorrect information)
Even though ethylene biosynthesis happens throughout the banana most-likely none of it occurs in the stem itself as it contains a small percentage of the metabolically active tissue. There aren't as many studies that focus on the stem of the banana specifically as I imagine it's not a very attractive topic, but the current-day findings that we have highly support the assumption of insignificant ethylene gas production (or none at all) in the banana stem and it's why wrapping it will pose virtually no difference in the further ripening of a banana.
Links to relevant studies: (1) (2) (3)