Keep Bananas Fresh Longer (slices, Too!)

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Posted in FoodBreakfast

Introduction: Keep Bananas Fresh Longer (slices, Too!)

About: I'm an English teacher and former Instructables staff member.

For many people, purchasing a bunch of bananas is the ultimate act of hope in the face of experience.

I'm no different. My thinking generally goes, "If I buy these now, I'm set on breakfast for a week." Then Thursday comes around, my 'nanners have turned brown, and suddenly Friday's looking like a toaster waffle sort of day. Sometimes I consider baking banana bread and pretending I meant to let them get overripe, but mostly I throw them away and feel bad.

There is another way. A better way. A way that requires nothing more than what is already likely to be in your kitchen.

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Optional science!

We're looking specifically at enzymatic browning and the effect of ethylene production here. If you want to dig much deeper, there's a ton of academic research on bananas available online.

"Relationship between browning and the activities of polyphenol oxidase and phenylalanine ammonia lyase in banana peel during low temperature storage" anyone?
(Postharvest Biology and Technology - PDF link)


When fruits or vegetables are peeled or cut, enzymes contained in the plant cells are released. In the presence of oxygen from the air, the enzyme phenolase catalyses one step in the biochemical conversion of plant phenolic compounds to form brown pigments known as melanins. This reaction, called enzymatic browning, occurs readily at warm temperatures when the pH is between 5.0 and 7.0.
(Australian Institute of Food Science and Technology - PDF link.)


Ethylene promotes maturation and abscission of fruits. This has been known since early last century. Since 1934, it is known that plants themselves can produce ethylene. Many climacteric fruits such as apple, banana and tomato show a strong increase in ethylene levels at the late green or breaker stage. As a consequence of high ethylene chlorophyll is degraded and other pigments are being produced. This results in the typical color of the mature fruit peel. Activity of many maturation-related enzymes increases. Starch, organic acids and in some cases, such as avocado lipids, are mobilized and converted to sugars. Pectins, the main component of the middle lamella are degraded. The fruit softens. These metabolic activities are accompanied by a high respiration rate and consequently by high oxygen consumption. Ethylene levels are especially high in the separating tissues resulting in abscission of the fruit.
(Margret Sauter, University of Hamburg.)

Step 1: Preserve the Bunch: Wrap Stems With Plastic Wrap

To keep a bunch of bananas fresh for longer, wrap the stems in some plastic wrap. Re-cover the bananas with the wrap after removing one.

This method prevents ethylene gas, produced naturally in the ripening process, from reaching other parts of the fruit and prematurely ripening it. This technique is hit or miss, as the coverage from the plastic wrap is unlikely to fully prevent contact with the ethylene gas. It's certainly better than nothing, though.

This explains a few common tricks about using bananas to ripen other fruits like avocados. Or quick-ripening bananas by storing them all in a bag together. Ethylene is actually used in the banana production facilities to induce ripening at just the right time to ensure that you buy a bunch of yellow (or greenish yellow) from your local grocer.

(The next step is my preferred method, and the one that the science appears to back up with the most evidence.)

Step 2: Separate, Then Wrap the Stems

Sure, wrapping the whole stem section works, but why keep the bananas together? Since most bananas on a bunch ripen at slightly different rates, your prematurely ripe bananas are going to put off more ethylene gas which will only serve to make ALL the bananas ripen that much faster.

Divide and conquer! Separate the ripe fruit from the slightly-less-ripe, wrap their stems in plastic, then enjoy when you're ready.

This should do a couple of things:
  1. prevent ethylene gas from initiating the ripening process on under-ripe bananas
  2. fully cover the stem to really forestall the off-gassing
  3. make your bananas more convenient to grab and enjoy on the go
And if you're bothered by the stem wrapper, try opening your bananas from the opposite end like a monkey. You'll get fewer stringy bits and have a convenient handle to hold onto while you eat. Also, no awkwardness for that final bite.

Step 3: Keep Banana Slices Fresh

To prevent your banana slices from browning, you can use the same trick you've seen for apples: acid!

Just toss your banana slices in some lemon juice to inhibit enzymatic browning. Full coverage, particularly on the cut sides, will help prevent the slices from turning brown. In addition to lemon juice, vinegar will also work. So would sulfuric acid, for that matter, but you probably don't want to eat it afterwards.

The acid disrupts the enzymatic breakdown process and prevents your sweet, sweet banana slices from turning into mushy little brown hockey pucks.

A dab'll do ya, so keep your acid in the teaspoon range. Or you'll just have sour bananas.

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128 Comments

So I tried it with a lot of bananas, and it simply did NOT work. See my results here: http://imgur.com/gallery/j8lRC

I'd like to have experience returns of people for who that worked.
@OP: did you try it before posting it?

2 replies

Looking at your pictures you left some of the "stem holder" attached to the stem.
I found that you must have only stem, no "stem holder" in order for them to last longer...

From your results, it looks like separating the bananas followed by wrapping has no discernible visual effect. You busted my myth!

I tested separation but NOT wrapping. That was a bit of leap to synthesize the research around off-gassing and anecdotal reports that wrapping the stems made a difference. Clearly, it makes no aesthetic difference. (You mind if I incorporate your photos to make this ible more accurate?)

user

This article seems to assume that all of the ethylene either comes out of the stalk to be absorbed by the banana, or enters in via the stalk. Isn't the ethylene generated by the banana itself, all over? How does wrapping up just the stalk affect anything?

I tried it to see if it would make any difference, and it was a resounding failure. I kept two bananas on my desk, about 9-12 inches apart (I briefly moved them closer for each photograph), one with stalk wrapped tightly with clingfilm (see fifth close-up photo) and one without. By the fourth day I don't think there is any significant difference between the two (or, in fact, on days 1, 2 or 3)!

I'm going to eat them now!

day1.jpgday2.jpgday3.jpgday4.jpgwrappings.jpg
7 replies

I too was looking forward to writing up a method for banana immortality.
I had practiced the "wrap the stem holder" with plastic wrap, which worked.
I separated the bananas from the "stem holder" and wrapped the end of the stem.
I numbered the bananas with a marker and took a picture.
In prepping to write up an Instructable I left three unwrapped, expecting early browning on those three.
More pictures taken to illustrate the step.
Imagine my surprise when I found that the three didn't age sooner!
The conclusion is that cutting them free of the "stem holder" is all that it took to make them last longer.
In my opinion they taste sweeter as well.
I was surprised and thought I may have done something wrong so I bought another hand of bananas and left half of one hand attached to the "stem holder" and cut the others from the "stem holder."
I wrapped the "stem holder" and did nothing to the individual stems (other than cut them off the "stem holder")
Being attached with wrap made them last longer but not as long as the singles.
Go figure...

Sorry for performing necromancy on this thread, but this bears stating: Ever since you tested and confirmed that wrapping the stem has no effect, I've wondered how I ever came to that conclusion. Well, I finally figured it out! I made an incorrect leap of imagination about ethylene production and abscission, the natural splitting of leaf or fruit from stem.

I re-read the Sauter paper and realized that I got a little too inferency. I thought that since ethylene caused abscission, it would make sense to cover the point prone to abscission. I didn't test when I saw confirmations from Lifehacker and eHow. (I know! Those were my sources after all the research I'd done?! I'm embarrassed for me, too.)

Thanks for eating bananas for science!

These two bananas look like twins!

user

I think most bananas *are* "twins", in a sense, aren't they? Since the plants are all propagated by cloning another plant, and the fruit are unfertilised:

http://en.wikipedia.org/wiki/Bananas#Modern_cultivation

Maybe 'twins' isn't quite the right word but they all come from a relatively small number of "mothers" that have been cloned millions of times. This is probably why most bananas look very similar, unlike, say, apples.

8-)

Although they were treated differently, they looked the same, like twins to me. Good selection of experiment samples.

user

Note that I should point out the photos above are in order on Day 1 (purchase day), Day 2, Day 3 and Day 4. I kept them separated by 9-12, apart from during their photoshoots, in case the ethylene from one banana affected the other.

Hrm, great experimenting and documentation. And of course interesting result...

The idea of using lemon juice is really great. I do a lot of cooking and I've been using lemon juice for years.This works great with potatoes as well, which is just about as bad as bananas to turn dark after pealing. Here's something you may want to try: when making a banana pudding, peal and slice the bananas as usual and toss them in the limon juice. This will give your pudding the most wonderful tangy taste. I find the contrast between the very subtle sour taste and the sweet taste to be absolutely marvelous. For six bananas I use one to two tablespoons. Go easy at first and then adjust to suit your taste.

I can't believe with all this research discussion none of have realized the way to keep bananas fresher longer is to put them in the refrigerator. WHAT??!!! Yes, the skin turns black but the fruit itself lasts longer. This is even suggested by the producers. Putting them drastically slows the ripening process while causing a chemical reaction in the skin that turns it black. I created an account just to tell you all this. I probably wont use this site much based on the "bad science" displayed here.

1 reply

This site has tons of useful information keep looking around. Humans make errors and miss understand things or forget details don't let one post ruin your experience. I don't even like bananas I don't even know how I got here.

I've found that if I keep the bananas in a bag they last long enough to eat through the week.

I used to have the exact problem as you. Buy them on Monday and before Friday they're brown. But I once left them in the bag and discovered they lasted a long time. BTW: paper bags work even better then plastic bags.

This is nonsense. It is an Internet myth, like many Internet things. I tested this for the past year. Time after time, bananas with stems wrapped or hung certain ways lasted no different on average than not doing anything special. I tested this 14 times in various combinations. The one thing that ALWAYS made a difference was keeping the banana in a refrigerator. I also tested bananas in the dark, to see if the dark of the refrigerator was part of the change. They lasted no differently if in dark or normal room light.

Cool suggestion! Will try it??!?

user

“try opening your bananas from the opposite end like a monkey”

— how do you open a monkey?

1 reply

with an axe