Need Ripe Bananas Fast? Mash Them First

"With these methods, you are technically cooking the banana rather than ripening it, and they won't convert the starches in the same way natural ripening would. But they will tenderize the banana's flesh and turn it somewhat sweeter. Verdict: For bananas with soft flesh, the microwave and oven methods can't be beat for speed, but their flavor might be lacking."

"Another option is to mash the underripe bananas with any eggs in your recipe. Proposed by Stella Parks of Serious Eats, this method takes advantage of the amylase present in the egg yolks. A starch-breaking enzyme, amylase plays a crucial role in banana ripening. Mixing the underripe banana flesh directly with the egg triggers a chemical reaction that quickly breaks down the fruit's starches. After 30 minutes, you'll have a mash ready for any and all banana baked goods."

"Logic has it that sequestering an unpeeled banana in a brown paper bag traps its natural ethylene gas-the plant hormone that triggers ripening-and, in turn, expedites the ripening process. When I performed this test in my apartment at room temperature, I found that after 3 days, my paper-bag bananas boasted the same level of spottiness as those left exposed on the counter. A plastic bag elicited identical results."

Microwave and oven techniques technically cook bananas rather than ripen them and do not convert starches the same way natural ripening does. Heat methods tenderize the flesh and increase sweetness but often yield less complex flavor. Mashing underripe bananas with eggs uses amylase in egg yolks to rapidly break down starches, producing a usable mash in about 30 minutes. That egg method delivers speed and sweetness but lacks the complexity of naturally ripened flavor. Sequestering unpeeled bananas in paper or plastic bags does not significantly accelerate ripening at room temperature. Placing bunches high, such as atop a refrigerator, can promote faster natural ripening.

Read at Epicurious