Actually, yes. As bananas ripen, the starch in the flesh is converted into sugar (with, I believe, glucose and fructose being the highest amount). This will continue until the starch providing the banana's structure and firmness has mostly turned into sugar. Basically, the blacker the banana gets, the more time the starch has to convert to sugar, meaning a much sweeter banana.
When the peel is completely black, most of the starch will have converted to sugar; that would be the time to "harvest" the banana inside. Even when the skin is almost completely black, they're still edible, often used in breads and make the SWEETEST smoothies!!
And of course
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