# Nitrogen+Bananas **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [May 12, 2015, 8:16am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844 "2015-05-12T08:16:29Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![toefungus](https://avatars.discourse-cdn.com/v4/letter/t/b487fb/32.png) [@toefungus](https://boards.straightdope.com/u/toefungus)\ **Post date:** [May 12, 2015, 8:16am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/1 "2015-05-12T08:16:29Z")
Last time I checked the air was about 80% nitrogen. Storing a banana next to a mango won’t do much. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [May 12, 2015, 8:27am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/2 "2015-05-12T08:27:26Z")
It would be _really helpful_ if you linked to whatever you’re commenting on so I have some context for your statement. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 12, 2015, 11:13am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/3 "2015-05-12T11:13:11Z")
I assume he means [this column about refrigerating bananas](http://www.straightdope.com/columns/read/1412/if-you-refrigerate-bananas-do-they-become-poisonous). How much nitrogen is in the air is irrelevant. Ripening fruit give off ripening agents like ethylene and keeping ripening fruit together increases their exposure to the ripening agents. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 12, 2015, 11:19am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/4 "2015-05-12T11:19:34Z")
The questioner was possibly confused by the fact that when bananas are shipped long distances, they’re in a pure nitrogen atmosphere. This unsurprisingly slows their ripening, as nitrogen is quite unreactive. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [May 14, 2015, 2:15pm UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/5 "2015-05-14T14:15:10Z")
> [@Chronos](#): > > The questioner was possibly confused by the fact that when bananas are shipped long distances, they’re in a pure nitrogen atmosphere. This unsurprisingly slows their ripening, as nitrogen is quite unreactive. Whereas oxygen, most of the remainder (like 21%)…almost the very [definition of reactive](http://en.wikipedia.org/wiki/Oxidizing_agent). By the OP’s logic, there’d be no difference between breathing normal atmosphere and breathing pure nitrogen, so [inert gas asphyxiation](http://en.wikipedia.org/wiki/Inert_gas_asphyxiation) would be a pretty ineffective form of execution. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [May 22, 2015, 9:43am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/6 "2015-05-22T09:43:04Z")
> [@TriPolar](#): > > How much nitrogen is in the air is irrelevant. Ripening fruit give off ripening agents like ethylene and keeping ripening fruit together increases their exposure to the ripening agents. He’s talking about the comment in the question by David Grodsky: > [@](#): > > There is also a woman I work with who states bananas give off nitrogen so the best way to keep them fresh is to keep them next to an unripe mango which absorbs nitrogen. Incidentally she says this also keeps the mango fresh. What do you think of all this? If a ripening banana gives off nitrogen, will lowering the nitrogen content around it keep it fresher? That’s what David’s coworker thinks. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [May 23, 2015, 9:18am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/7 "2015-05-23T09:18:17Z")
The OP’s logic is perfectly sound; the presence of large amounts of nitrogen in the air logically excludes any effects from any (imaginary) nitrogen emissions from the banana. And as Chronos has said, nitrogen inhibits ripening. The gas that ripens fruit is ethylene, as Tripolar mentioned. > **[Ethylene](https://en.wikipedia.org/wiki/Ethylene#List_of_plant_responses_to_ethylene)** > > Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula .mw-parser-output .template-chem2-su{display:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em}.mw-parser-output .template-chem2-su\>span{display:block;text-align:left}.mw-parser-output sub.template-chem2-sub{font-size:80%;vertical-align:-0.35em}.mw-parser-output sup.template-chem2-sup{font-size:80%;vertical-align:0.65em}C2H4 or H2C=CH2. It is a colourless, flammable gas with a faint "sweet and musky" odour when pur... Most fruits, except mangos, pineapples and citrus fruits, produce ethylene. > **[Role of Ethylene in Fruit Ripening](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC549760/)** ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [May 23, 2015, 10:10am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/8 "2015-05-23T10:10:24Z")
It’s not nitrogen that inhibits ripening but the lack of oxygen. The final step of ethylene biosynthesis requires oxygen and removing it stops ethylene production and hence ripening dead in its tracks. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [May 23, 2015, 10:48am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/9 "2015-05-23T10:48:08Z")
Any inert gas would do, although I’d advise against xenon, as it is a potent anaesthetic. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [May 23, 2015, 8:09pm UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/10 "2015-05-23T20:09:17Z")
> [@Irishman](#): > > He’s talking about the comment in the question by David Grodsky: > > If a ripening banana gives off nitrogen, will lowering the nitrogen content around it keep it fresher? That’s what David’s coworker thinks. Le Chatelier would tend to disagree. If we stipulate that ripening bananas generate nitrogen, then surrounding them with pure nitrogen should inhibit ripening. I haven’t accepted the first premise, but if it is true, then the second should follow. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 24, 2015, 3:09am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/11 "2015-05-24T03:09:20Z")
Doesn’t work. Ripening bananas (or nearly any other fruit) do in fact generate ethylene, and surrounding them with pure ethylene encourages ripening. Which incidentally leads to the question: Why is ripening encouraged by a gas produced by ripening? Presumably, there’s some benefit to the plant for all fruit in a region to ripen simultaneously, and so this gas system evolved, but what would that benefit be? I can’t think of any explanation consistent with the fruits also evolving to be good food sources for animals. ---
**Author:** ![drewder](https://avatars.discourse-cdn.com/v4/letter/d/57b2e6/32.png) [@drewder](https://boards.straightdope.com/u/drewder)\ **Post date:** [May 24, 2015, 4:07pm UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/12 "2015-05-24T16:07:50Z")
> [@eburacum45](#): > > Any inert gas would do, although I’d advise against xenon, as it is a potent anaesthetic. I’d avoid radon as well. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [May 24, 2015, 11:40pm UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/13 "2015-05-24T23:40:24Z")
> [@Bill\_Door](#): > > Le Chatelier would tend to disagree. If we stipulate that ripening bananas generate nitrogen, then surrounding them with pure nitrogen should inhibit ripening. I haven’t accepted the first premise, but if it is true, then the second should follow. Read my post again more closely. I did not say surround the banana with pure nitrogen. I did not even say increase the nitrogen around the banana. I said pair the banana with an unripe mango, which _absorbs_ nitrogen. Ergo, there is less nitrogen around the banana. According to Le Chatelier’s principle you cite, that should make the banana ripen faster. > [@Chronos](#): > > Which incidentally leads to the question: Why is ripening encouraged by a gas produced by ripening? Presumably, there’s some benefit to the plant for all fruit in a region to ripen simultaneously, and so this gas system evolved, but what would that benefit be? I can’t think of any explanation consistent with the fruits also evolving to be good food sources for animals. Many fruits include the seeds but also a fleshy coating. The fleshy coating encourages being eaten, thereby breaking up and spreading the seeds, or perhaps passing the seeds through the digestive tract to be spread elsewhere. Having all the fruits ripen at once means more animals drawn to area, thus more distribution. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 25, 2015, 12:06am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/14 "2015-05-25T00:06:07Z")
That only works if you can draw in enough animals to eat _all_ the fruit, and even then, the animals still have to get there at the right time, and then get someplace else to eat the fruit there so they don’t starve. It seems like it’d make more sense to have a smaller food supply for the animals that’s steady over time, from fruits ripening at different times. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [May 25, 2015, 7:47am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/15 "2015-05-25T07:47:48Z")
> [@Irishman](#): > > Read my post again more closely. I did not say surround the banana with pure nitrogen. I did not even say increase the nitrogen around the banana. I said pair the banana with an unripe mango, which _absorbs_ nitrogen. Ergo, there is less nitrogen around the banana. According to Le Chatelier’s principle you cite, that should make the banana ripen faster. I would like to know by what mechanism an unripe mango absorbs nitrogen, and what happens to the spectacularly unreactive nitrogen gas once it is absorbed by the unripe mango. Have you discovered a new method of nitrogen fixation? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 25, 2015, 2:00pm UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/16 "2015-05-25T14:00:16Z")
It doesn’t, but someone somewhere along the line had the impression that it did, and we’re exploring what implications it would have if true. However, most of what was originally said about nitrogen is actually true if we replace it with ethylene instead. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [May 25, 2015, 3:36pm UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/17 "2015-05-25T15:36:34Z")
Well, then. I’d also like to know how a banana generates nitrogen. As far as I know, only certain bacteria can perform denitrification, i.e., reduce nitrates back into nitrogen, and only under anaerobic conditions. If you’ve discovered that a banana can do this, in the presence of oxygen, no less, you’ve made a monumental discovery. Come to think of it, the magical nitrogen-fixing mango is surrounded by huge amounts of nitrogen in the form of the atmosphere. In order for the magical denitrifying banana to have any effect in the supposed nitrogen-activated ripening of the magical mango, the magical banana would have to pump out nitrogen at a prodigious rate. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [May 26, 2015, 6:38am UTC](https://boards.straightdope.com/t/nitrogen-bananas/719844/18 "2015-05-26T06:38:07Z")
> [@Chronos](#): > > That only works if you can draw in enough animals to eat _all_ the fruit, and even then, the animals still have to get there at the right time, and then get someplace else to eat the fruit there so they don’t starve. It seems like it’d make more sense to have a smaller food supply for the animals that’s steady over time, from fruits ripening at different times. I agree. However, some plants do have a weird synch cycle that works to their advantage, but also spawns a surge in animals eating them. Witness bamboo, its weird mass flowering cycles as long as 150 years, where all the plants anywhere in the world derived from the same progenitor by cloning will flower at the same time. > **[Bamboo](https://en.m.wikipedia.org/wiki/Bamboo)** > > Bamboos are a diverse group of mostly evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in the case of Dendrocalamus sinicus having individual stalks (culms) reaching a length of 46 meters (151 ft), up to 36 centimeters (14 in) in thickness and a weight of up to 450 kilograms (1,000 lb). The internodes of bamboos can also be of great length. Kinabaluchloa wrayi has internode In ba... Interestingly, this also spawns a massive surge in rat population that devoirs the bamboo, and goes on to March into inhabited areas and destroy crops. That wikipedia page says a predator satiation hypothesis had been proposed, with the idea the mass flowing assures the predators can’t devour all the seeds. So petals that’s the explanation. Create more fruits and thereby seeds than can possibly be devoured and increase reproductive survival. > [@Terminus\_Est](#): > > I would like to know by what mechanism an unripe mango absorbs nitrogen, and what happens to the spectacularly unreactive nitrogen gas once it is absorbed by the unripe mango. Have you discovered a new method of nitrogen fixation? It is not my proposal or claim. It is the claim of someone cited by the person who asked the original question to Cecil. I was pointing out what the OP of this thread was addressing, since several posters apparently missed it. > [@Terminus\_Est](#): > > Well, then. I’d also like to know how a banana generates nitrogen. I have no idea, and would love to know where the idea came from. Some old wives’ tale, I guess. > [@](#): > > Come to think of it, the magical nitrogen-fixing mango is surrounded by huge amounts of nitrogen in the form of the atmosphere. In order for the magical denitrifying banana to have any effect in the supposed nitrogen-activated ripening of the magical mango, the magical banana would have to pump out nitrogen at a prodigious rate. Agreed. I think the claims are ridiculous. Both about bananas and mangoes. I think it is just possible that a paper bag could be used to slightly concentrate a gas being expelled by a fruit, and a fruit that absorbs that gas would be affected by the gas increase. But nitrogen is pretty ubiquitous in the atmosphere, and relatively inactive. That’s why plants need chemical fertilizer - they don’t get nitrogen via the air, but through the roots.