Odd thoughts from Breakfast.

[IDMclean]

I was wondering, as I had not thought about it before. Are the spots on bananas the result of radiation from the radioactive isotope of potassium?

 

[math] 19, Postassium, K, 39u, 93.2581%[/math]

[math] 19, Postassium, K, 40u^*, 0.0117%, 1.28*10^9 years[/math]

[math] 19, Postassium, K, 41u, 6.7302%[/math]

[math]^*[/math] indicates Radioactivitity.

[Jay-qu]

I dont think so... its just the cells breaking down as the thing 'dies'

even if it was radiation it wouldnt be potassium, 10^9 years is a long time

[anglepose]

its just bannana bruising basicly the cells die out like jayqn said and cuase the banana isnt being fed it cant heel itself

[InfiniteNow]

Oxidation too.

[IDMclean]

Well I was just thinking about something I heard a while ago, that bananas have a higher rate of the radioactive isotope than most other collections of potassium and it occured to me that the little brown spots could be similar to that of the brown spots that appear on the oiled paper, I forget who or what or when, I just remember the paper and it's spots, cause the ?alpha? radiation causes the oil in the paper to ionize. A similar thing could happen in the banana, as it ripens.

 

It's just a thought.

[Mercedes Benzene]

Its definitely not a result of radiation.

 

Although an alarmingly high amount of radiation resulting from the decay of a potassium isotope can be found in the common salt substitute: Potassium Chloride....

in a local supermarket near you!

[CerebralEcstasy]

I was wondering, as I had not thought about it before. Are the spots on bananas the result of radiation from the radioactive isotope of potassium?

 

[math] 19, Postassium, K, 39u, 93.2581%[/math]

[math] 19, Postassium, K, 40u^*, 0.0117%, 1.28*10^9 years[/math]

[math] 19, Postassium, K, 41u, 6.7302%[/math]

[math]^*[/math] indicates Radioactivitity.

 

I found the following link to be rather interesting. They seem to indicate most of the browning comes from chilling/or skin abrasions.

 

http://postharvest.ucdavis.edu/Produce/ProduceFacts/Fruit/banana.shtml

 

You didn't really specify if you were talking about the inside of the banana or the skin of it.

 

Which made me wonder whether the gases they use to ripen them might have any direct bearing on the spotting.

 

When you observe them ripening, you see many tiny little spots (on the skin), almost like what you might see when a thin spray of water beads on something. Maybe the gases condense on the skin and stay there unnoticed until it browns?

[IDMclean]

I am refering to the skin.

 

40K occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. In healthy animals and people, 40K represents the largest source of radioactivity, greater even then 14C. In a human body of 70 kg mass, about 4,000 nuclei of 40K decay per second.

 

225 grams (1 cup) of banana has 806 mg of potassium

 

So... what are the chances you suppose?

 

Note on half-life:

Half life is the measure of time it takes (On Average) for half the radioactive material to decay. Something that is radioactive will still throw off Alpha, Beta, or Gamma Radiation in short spans.

[Grazza]

If the spots on the banana were to be a symptom of radiation poisoning, i would have thought that they would be more uniform over the banana's surface. After all, the potassium would be shared roughly equally around the banana's cells, so instead of getting brown patchy spots, i would expect the whole banana to just gradually darken. Also the flesh of the banana does not go brown (unless you drop it/mash it into a sandwich, great!) and a high proportion of the potassium is to be found here.

 

So i don't think radiation has anything to do with the banana's ageing.

 

Of course, in a few years time, there may not be bananas anymore, unless something is done to strengthen the poor clone's gene pool. So i think we should appreciate them whilst we can.

[IDMclean]

Well actually, no the little ammount of radiation that would come off of the few isotopes of potassium would be speratic and would generate little spots like that. If I remember correctly the Potassium Isotope is a alpha source... I think.

 

High levels of Radiation, like a nuke, would create a consistant browning over the entire thing.

 

Keep in mind that I am talking low level, background radiation. safe levels. No need to panic here people, bananas are good for you and a little tiny bit of radiation is not going to make you deathly ill, or nessessarily ill at all.

[Erasmus00]

The brown on the banana is caused, as earlier mentioned, by oxidation.

 

An interesting historical note on radioactive potassium: when William Thompson (Lord Kelvin) used the heat equation to calculate the age of the Earth he decided it couldn't be older then 98 million years or so. So what went wrong with his calculations? Radioactive potassium (with a half life on the order of Thompson's age of the Earth) heats the Earth as it decays.

-Will

[EWright]

I am refering to the skin.

 

 

 

 

 

So... what are the chances you suppose?

 

Note on half-life:

Half life is the measure of time it takes (On Average) for half the radioactive material to decay. Something that is radioactive will still throw off Alpha, Beta, or Gamma Radiation in short spans.

 

so fruit is now giving off gamma bursts of radiation... interesting.

[IDMclean]

Not gamma I think. It's either a Alpha or a beta, I think it's just an Alpha. and low level at that.

[cockydude]

Radiation wouldn't be insane but i certainly do think that it could just be the cells or oxidation. Possibly genetics? Never had time to observe any patterns but it could be an inherited trait