Bananas are tropical fruits that are popular in the Mediterranean, Caribbean, South, Southeast and East Asia and Latin American regions. A good source of potassium, it is often confused with plantains, a fruit native to India and the Caribbean islands that is essentially the same but has lower starch and sugar content and is still green even if it is already ripe.
Bananas emit ethylene which is responsible for softening and changing the colors of the fruit. They key to accelerating the ripening of bananas is manipulating its exposure to ethylene.
Here are some ways to maximize bananas’ exposure to ethylene:
Make sure that the bananas stay in a bunch with other fruits.
The combined ethylene emitted by the bananas would collectively help speed up the ripening process.
Pro-tip: Placing bananas with other ethylene-rich fruits like tomatoes and apples also quicken the bananas’ ripening process.
Store the bananas in a warm place.
Exposing the bananas to warmth brings out the fruit’s sugar and will mean that the bananas will be ripe in 24-48 hours. Just make sure that you check on them once in a while. If brown spots start appearing, that means it is now ripe.
Place the bananas inside a paper bag.
Putting bananas inside the paper bag speeds up the ripening by suppressing the emission of ethylene within the confines of the bag so it only builds up and circulates around the banana. This method also traps warmth within the bag which also stimulates ripening. The bananas will be ripe within 12-24 hours so you can do this at night and then check on them in the morning when you wake up.
Use an oven or a freezer.
If you want instant gratification, placing the bananas in an oven is a great idea. Turn the oven on at the low heat of 250°F and leave it for 15—20 minutes.
The opposite also works: you may put the bananas for at least two hours in the freezer and it will have the same effect.
Fair warning though, exposing the bananas to extreme temperatures can make it mushy and too sweet so do it only depending on what you will use it for (mushy and saccharine bananas would produce very tasty banana bread). Both methods also turns the banana peels black so if you are going to use the bananas for presentation purposes, you might want to shun the oven and freezer and opt for the other ways.