How to keep bananas ripe
I eat a banana every day, and I am always trying to optimize the combination of ripeness of the bananas that I buy. I often buy a couple of totally yellow ones, along with a few green ones for after I’ve eaten the yellow ones. But I totally misjudge them sometimes and end up eating a brown mush, or a hard, almost bitter thing that I can hardly get the skin off of.
Below, I’ve copied some snippets of info I found on ripening fruits. A lot of people know this stuff already, but I didn’t think to keep bananas in the fridge, and I can never remember which fruits continue ripening (i.e., which ones you can still have hope for) and which ones are WYSIWYG.
Bananas when harvested mature have very high levels of starch (like a potato). During ripening this starch is converted to soluble sugars and that is why they taste sweeter when they are ripe. The hormone ethylene is normally used to trigger ripening in bananas (and also avocados) by applying ethylene gas into a ripening room for a period of time. The application of ethylene gas helps to reduce fruit to fruit variability in ripening time as well shortening the overall ripening time.
The avocado and banana are classified as climacteric fruits whereas the pineapple is classified as a nonclimacteric fruit. Nonclimacteric fruit do not exhibit the increase in respiration nor the rise in ethylene production nor do they normally undergo dramatic changes (such as softening) after harvest.
(from Howstuffworks “Health Benefits of Fruits…”)
Fruits that will continue to ripen [climacteric]:
Fruits to buy ripe and ready to eat [nonclimacteric]:
From “Fruit Ripening”:
How can you assist fruit ripening? First let me tell you that bananas are shipped to the US as hard, green, sour, unripened fruits. They ship better that way. They arrive into a distributor’s warehouse without bruises. The bananas are put in a room and gassed with ethylene. They all begin to ripen. You buy them at the store and within a few days the ripening process is so rapid that the bananas are “over the hill” before you can eat them all.
By the way, you can allow the bananas to ripen to the stage you like them and then put them in the refrigerator. This slows the ripening process down drastically. For several days after that you can take bananas from the refrigerator and enjoy the fruit inside. Please note: the skin will turn very dark in color after only a short time in the refrigerator…you can ignore that…the fruit inside remains just as it was before you put the banana into the refrigerator.
The ripening bananas produce so much ethylene that you can use them as a tool to ripen other fruits. Take those green pears home and put them on the shelf in a paper bag with a banana. The banana at room temperature produces ethylene that will signal the green pears to start ripening immediately. The paper bag holds the ethylene in stagnant air around the fruits, yet allows oxygen to go into the bag for respiration in the fruits…needed to make the enzymes! In just a few days the pears should be ready to eat! You can do the same with avocados.