Ripening avocados in the oven: old wives’ tale or extremely effective truth bomb?

By Betty Gold
Updated: June 04, 2019

How many times have you been dying for chips and guac only to find yourself digging through a mountain of rock-hard avocados at the grocery store? Or maybe your plans for having peanut butter-and-banana toast for breakfast were spontaneously spoiled when you discovered the entire bunch turned brown overnight. This week at Real Simple, we set out to test popular myths about speeding up and slowing down fruit and vegetable ripening.

Before we jump in, let’s begin by defining what ripening is. This process is the result of fruit releasing a gas called ethylene, which effectively starts the course of decay. Ripening is caused by the breakdown of cell walls, conversion of starches to sugars, and the disappearance of acids in a piece of produce. All of these processes make a peach or pear more palatable—it’ll feel softer and taste sweeter with less acid, starch, and softer cell walls—only up to a point (when it gets rotten). Because ethylene gas diffuses easily, it can travel within the plant from cell to cell and to neighboring plants. This signaling serves as a warning signal to nearby plant life that danger could be close and that it’s time to activate the appropriate defense responses. 

Biologists, food scientists, and our own grandmothers have been tinkering with the manipulation of ethylene gas since the beginning of time. According to all of the above, exposing certain fruits to ethylene gas in the critical window will speed up ripening. Fruits that are affected by ethylene gas include apples, bananas, peaches, mangoes, pears, tomatoes, avocados, and more. Those that won’t respond to ethylene are oranges, grapes, pineapples, and many berries. Food for thought! Here are the ripening rules that work and those that won’t.

Can you slow the ripening of bananas by wrapping their stems in saran wrap?

We read that ethylene gets emitted from the stem of bananas, and if you tightly cover them up, you can keep your bananas kicking (read: yellow) a lot longer. We purchased two identical banana bunches to test out this trick. Half stayed as-is, and half got the saran wrap treatment around their stems. A week later, we checked on their color, texture, and taste.

The result was a major surprise. The bananas we wrapped with saran were actually more rotten than the bare bunch. Compared to the regular ones, the wrapped bananas had more brown spots, thinner and more delicate peels, and many of them actually fell apart when we picked up the bunch. This could have been completely coincidental, but regardless, we recommend you skip the saran wrap. We tried the same experiment with separated bananas (i.e. not in a bunch) and also didn’t notice any difference. Declaring this one a myth! But if you are interested in ripening bananas faster, check out these genius tricks.

Can you ripen a mango in a bag of rice?

Both of us were so eager for this trick to work, because few foods are better than a sweet, soft mango—and nothing’s worse than a stringy, tasteless rock that’s posing as one. The theory behind ripening a hard mango in rice is that the rice ‘concentrates’ the ethylene around the fruit, thereby holding it in and utilizing it, rather than feeding the precious gas to the outside air. (The idea’s the same as putting an under ripe fruit into a brown paper bag like mom used to do.)

We bought two identical under-ripe mangoes and dropped one in a big bag of rice and left the other out on its own at room temperature. After five days, we fished our mango out from the rice and held the two next to one another and could feel that is was significantly softer than the "control mango." We cut them open and to our delight, the mango that sat in the bag was bomb—super sweet and juicy. The one that sat out on the counter, however, was still sour, hard, and had plenty of stringy fibers throughout. Ladies and gentleman, it’s a hit.

RELATED: The Hassle-Free Way to Cut a Mango

But whatever you do, just don’t forget to check on your mango in the rice bag every day or so—otherwise you’ll come back to a rotten fruit and an entire bag of ruined rice.

Can you speed up the ripening of avocados by baking them in the oven?

Truly, if I had to choose between winning the lottery, turning water into wine, or being granted a way to always have perfectly ripe avocados at home, I’d always pick the path that leads to good guac. But when we heard that you can turn a rock-hard avocado into a tasty, tender one in 10 minutes in the oven at 200°F, we were skeptical. Willing to try anything, we wrapped our avocados in aluminum foil, placed them on a sheet tray, and let them bake.

To our disappointment, after 10 minutes, all that developed was an off-odor and a super slimy avocado flesh. After 30 minutes, it only got worse. The cooked avocados were certainly softer to the touch, but to call that strange-smelling fruit ‘ripe’ would be a great disservice to mankind. While heat does stimulate the production of ethylene gas, there’s a limit to how much you can move things along with warmth. Rather than encouraging the ethylene, the oven merely cooked the avocado, which can explain the overly soft-and-slippery texture. Big, (polyunsaturated) fat myth, fam.

Here are a few helpful takeaways from our toying-with-ripeness tests:

  • Be mindful of where you store your fresh fruit in the kitchen. Warmer areas can speed up ethylene gas production, and certain types of fruit stored close together can ripen one another.
  • Avoid manipulating ethylene gas production too long before a piece of fruit is ripe. You have to work within the critical window, which is just after ripening has already begun. If a fruit's exposed to ethylene well before it’s ripe, it won't do much. In fact, in some fruits it can stymie ripening.
  • To speed up ripening of the fruits listed above, you can store them in a brown paper bag with a banana. And to speed up the ripening of a mango, you can try tossing it into a bag of rice. Just check on it frequently so you don’t overdo it.
  • If you’re planning on serving a dish that requires a perfectly ripe piece of fruit (like guacamole or anything with fresh mango), you’ll have to plan ahead. If you're shopping a couple of days before your party, buy produce that’s slightly under-ripe. If you have a local purveyor that you know will sell you fruit that’s at peak ripeness, buy as close to your event as possible so the produce won’t over-ripen and rot.
  • To slow down the ripening process, you can store your fruit in the fridge.

Thanks for tuning in! For more Hit or Myth fun, see what happened when we tried cooking with random home appliances here. 

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