Why does my banana bread smell so fragrant and banana-y right out of the oven but lose most of its aroma as it cools? Does it mean that the cool bread will have less flavor than the warm, fragrant bread?
A little background on the chemistry of bananas may help answer your questions: The dominant aromatic compound in bananas, isopentyl acetate (IPA), also known as banana oil, is very volatile—more volatile than oils such as lemon, cinnamon, and peppermint—and evaporates readily at room temperature, taking with it that great banana aroma.
In fact, in tests where we placed IPA bought from a chemical supply company on preweighed cellulose filter paper and weighed the paper every minute, we found that an average of 85 percent of the IPA had evaporated in less than 10 minutes. Since flavor is perceived not only by our taste buds but also by our sense of smell, when the IPA in banana bread evaporates (which may take longer in a real loaf than in our contrived tests) the bread won’t taste quite as banana-y as a loaf straight out of the oven.
But we don’t recommend that you tuck into a steaming-hot loaf of banana bread in order to experience 100 percent of its fruity flavor: It’s important to let banana bread (and all quick breads) cool before serving for an optimal texture.