Recipes for banana bread always call for very ripe or even brown bananas. Can one get away with a yellow or slightly green banana?
We made three loaves of banana bread, one with green, one with yellow, and one with brown bananas. The first hurdle was mashing: Mashing a ripe banana is a cinch, but to mash a green or even a yellow one, you really have to put your back into it (or use the food processor) to get a smooth puree. We did our best, and once we had baked the breads, we found, as we’d expected, that the riper the banana the more flavorful the bread.
What we didn’t expect was that we’d discover a difference in the structure of the bread, too. Bread made with greenish bananas was “vegetal” and “astringent,” according to some tasters, but also taller and drier, with a more open crumb, as opposed to the desirably moist, dense, compact crumb of banana bread made with ripe fruit. Yellow bananas with a few brown spots also lacked adequate banana flavor, but the vegetal taste was gone and the textural difference in the breads was small.
Our science editor explained that as bananas ripen, some of their starch is converted into sugar. Sugar behaves like a liquid in baked goods, moisturizing and tenderizing, so bread made with ripe bananas not only is the sweetest and has the most banana flavor but is also the most moist.
THE BOTTOM LINE: Use very ripe, or even overripe, bananas for baking. To speed ripening by a day or two, put underripe bananas in a paper bag with a ripe banana or any other ripe fruit (ripe fruits emit ethylene gas, which speeds ripening).