Here's a doozy!

toxcrusadrApril 28, 2014

While looking up the K content of banana peels, this blog came up, which says banana peels are 42% potassium.

http://homeguides.sfgate.com/nutritional-values-banana-peels-plants-58851.html

Really? I know they're high but this is ridiculous. The blog cites an academic paper that lists 78 mg/g in its abstract. That's 7.8% if I'm moving my decimals right.

I tried to send in a correction but their system won't take my answer to the captcha thing so I don't think it went through. These people need to check their figures!

This post was edited by toxcrusadr on Tue, Apr 29, 14 at 12:06

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wayne_5 zone 6a Central Indiana

Even 7.8% is a lot of potassium going to the landfills per day.

    Bookmark   April 28, 2014 at 1:41PM
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toxcrusadr

Yes indeed, and I compost every one of them, either in the compost bin or by 'roadside composting' if I'm in a rural area with a nice ditch and there's no one around. :-p

    Bookmark   April 28, 2014 at 4:24PM
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pnbrown

If you think about it it's a massive transfer of K and other nutrients from the tropics to the landfills, incinerators, and septic fields of the north.

    Bookmark   April 28, 2014 at 6:35PM
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chickencoupe

Math. It'll do me good, they said. Some people should stay away from math.

    Bookmark   April 29, 2014 at 5:42AM
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toxcrusadr

pn, you're right of course...I'm seeing a kid at the table holding a banana peel and his mother is lecturing him.

"There are starving gardens in Ecuador that would be happy to have that!"

"Fine, YOU mail it to them!"

heehee!

    Bookmark   April 29, 2014 at 12:09PM
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glib(5.5)

Surely it is 7.8% dry weight. That is high but not impossible, and still result in, I am guessing, a few hundred milligrams per peel.

    Bookmark   April 29, 2014 at 12:13PM
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toxcrusadr

Yes, it's surely dry weight. It was the 42% that got me, even if it was dry weight! That would be a rather crunchy banana peel.

    Bookmark   April 30, 2014 at 2:46PM
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claireplymouth z6b coastal MA

Just an aside, that same reference states there's almost as much manganese as potassium in the banana peel. (76.20 mg/g manganese compared to 78.10 mg/g potassium). Manganese generally flies under the radar when you talk about nutritional deficiencies - something to worry about? or not?

Journal of Food Technology
Year: 2008 : Volume: 6 : Issue: 6 : Page No.: 263-266

Chemical Composition of Musa sapientum (Banana) Peels

B.A. Anhwange

Abstract: Musa sapientum peels were analysed for minerals, nutritional and anti-nutritional contents. The result of mineral content indicate the concentrations (mg g 1) of potassium, calcium, sodium, iron, manganese, bromine, rubium, strontium, zirconium and niobium to be 78.10, 19.20, 24.30, 0.61, 76.20, 0.04, 0.21, 0.03, 0.02 and 0.02, respectively. The percentage concentrations of protein, crude lipid, carbohydrate and crude fibre were 0.90, 1.70, 59.00 and 31.70, respectively. The results indicate that if the peels are properly exploited and process, they could be a high-quality and cheap source of carbohydrates and minerals for livestock.

How to cite this article:

B.A. Anhwange , 2008. Chemical Composition of Musa sapientum (Banana) Peels. Journal of Food Technology, 6: 263-266.

URL: http://medwelljournals.com/abstract/?doi=jftech.2008.263.266

Claire

This post was edited by claire on Wed, Apr 30, 14 at 17:24

    Bookmark   April 30, 2014 at 5:23PM
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claireplymouth z6b coastal MA

I'm assuming that the chemical composition of the banana flesh is similar to the peel, since few people eat the peel.

Several references, including
Medline Plus state that the safe upper limit is 11 mg of manganese per day, which would be greatly exceeded by consuming one banana and no one talks about banana toxicity.

There's something odd here, besides the original question of 42% potassium.

Claire

edit note: I'm assuming a dried banana must weigh more than one gram to get higher concentrations of manganese than 11 mg.

This post was edited by claire on Wed, Apr 30, 14 at 17:40

    Bookmark   April 30, 2014 at 5:35PM
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toxcrusadr

I don't think it's safe to assume that fruit and peel have the same composition. And keep in mind that those numbers are based on dry weight, and most of the weight of a banana is water.

Also, there could be a typo there, maybe a misplaced decimal? Note, everyone on the Interweb seems to quote the same numbers, probably from that same paper. Hey, it's all over the Internet, it must be true, right?

    Bookmark   May 1, 2014 at 10:54AM
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claireplymouth z6b coastal MA

I know I've made a lot of assumptions there, some of them shaky, but the paper raised a question I'd never thought about - i.e. the possibly high levels of manganese in bananas (I eat a lot of bananas).

You're right that the numbers from that one paper seem to be quoted all over, and there doesn't seem to be much else out there that might contradict or confirm the findings. Just now I tried to search for something that might show a difference between the composition of banana fruits and peels, but didn't find anything easily, and I don't care enough to continue.

A final note: I got side-tracked by an article on Smithsonian.com, The Funniest Fruit: A Brief History of Banana Humor

Claire

    Bookmark   May 1, 2014 at 12:47PM
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greenman62

FYI...
the first 3 sites i checked all said 300 micrograms (or .3mg)
of Manganese and 400mg or so of potassium
this sounds about right to me.
Potassium is a macronutrient

top plant macronutrients are...

the primary macronutrients:
nitrogen (N), phosphorus (P), potassium (K)

the three secondary macronutrients:
calcium (Ca), sulphur (S), magnesium (Mg)
http://en.wikipedia.org/wiki/Plant_nutrition

-----------

, it has been determined that each adult has about 15-20 mg of manganese stored in his or her body. Needless to say, this isn't very much, and in fact some people occasionally eat this much dietary manganese in a single day.

Bananas have .32mg per fruit -
- %16 daily recommended intake

RDI 19+ years, male: 2.3 mg

and are ranked 69th in manganese content of tested fruits.
(if i counted properly?)
http://www.whfoods.com/genpage.php?tname=nutrient&dbid=77

highest...

oats 1/4 cup = 1.92mg
Cloves 2 tsp = 2.53mg
--

potassium...

Bananas = 1

potassium - 400 mg
manganese - 300 micro gram
http://www.bmj-health.com/2012/04/benefits-of-bananas.html

also .3mg Mn
http://www.bitelog.com/banana-calories-nutrients?nutrient_no=315&nutrient_name=Manganese&redir=redir

and
banana 100grams (dry powdered)
Potassium = 1.4 grams

http://www.bitelog.com/t-9041-calories-nutrients.htm?nutrient_no=306&nutrient_name=Potassium&redir=redir&food_quantity_text=1&unit_no=1&action=Calculate+Potassium

    Bookmark   May 1, 2014 at 3:59PM
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claireplymouth z6b coastal MA

Thanks, greenman62. It looks like the original paper in the Journal of Food Technology lost control of their decimal points. A banana containing 400 milligrams of potassium and 300 micrograms of manganese sounds much more reasonable.

Claire

    Bookmark   May 1, 2014 at 4:29PM
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toxcrusadr

I wonder if we should tell them. They could at least correct the online version.

Edit: I sent a query to Medwell Publishing. Maybe it's just the abstract and the correct number is in the text of the paper. I can't see it w/o a subscription.

This post was edited by toxcrusadr on Thu, May 1, 14 at 17:11

    Bookmark   May 1, 2014 at 5:02PM
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pnbrown

In any case, I wish I lived within hauling distance of a banana-peeling factory.

    Bookmark   May 2, 2014 at 6:40AM
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writer333(Zone 4)

I've been told that kiwi fruits have quite a bit of potassium as well.

    Bookmark   May 2, 2014 at 9:30AM
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Mackel-in-DFW

LOL! How much you reckon they pay them monkies, down at the nanner peelin' fact'ry, Mr. Brown ? I didn't even realize there was such a thang. I have learn't somethin' new today! Plus, I won a dollar bet with a Buddie...and I don't gamble... "less there's a hunderd percent odds... I warned 'im, as' he wanted to bet twenty. M

    Bookmark   May 2, 2014 at 9:03PM
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