What eats aluminium?

The Xmas pudding has been left for a while covered in aluminium foil. I thought it would be ok like this, the pud can last months, but this year I don't think it's so safe. It looks like these holes have been corroded through from inside by contact with the pudding and there is some metal residue on the surface of the pud beneath the holes. What can there be in the pudding that has affected the foil? And does this mean that aluminium foil is not a food-safe covering?
xmaspud.JPG
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAsked:
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debuggerauCommented:
Aluminium foil takes hundreds of years to degrade, so I heavily doubt it due to degradation.
More than likely, its stuck to the pud and bonded more than the pudding on the inside, then a little bit of movement and the foil came apart.

It could also be from something sharp that came into contact with the pud+foil from the outside, causing it to dint into the pudding, tearing the foil.


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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
It's not a mechanical puncture, if you look the edges of the holes are a patter similar to a rust hole in a car. I don't think there's any mercury in the pudding, but there is fruit although it's been boiled for so long that it's a fairly homogenous mass now. Are there any acids that could be in there that attack aluminium?
Sorry about the quality of the picture but my camera had trouble focusing on the shiny surface.
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sgvillCommented:
Aluminum can be corroded by mercury.  There are legends of commandos going into airfields with mercury paste to sabotage enemy planes.   Don't know if its true or not.  But.. there are lots of sites that talk about it.  Here is one: http://www.periodictable.com/PopularScience/2004/10/1/index.html

Of course, if your food has mercury in it, that might be a bigger problem
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
I know mercury affects it. Apparently it acts as a catalyst and removes the oxide layer allowing the air to oxidise the clean metal below, removes this layer and eventually rots though whatever structure it is attacking. This is why you are not allowed to take a mercury thermometer on an airoplane in case it gets broken and spills. I don't think my pudding has any mercury in it though.
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sgvillCommented:
I've also just read that very alkaline solution(pH8,5 or more) will etch or corrode aluminum.  For instance sodium carbonate 10%(or even sodium hydroxide 2-5%) solutions are suggested if you are trying to corrode it.
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debuggerauCommented:
Yes, but mercury being so heavy should only affect the bottom of the container, and leave a different pattern.

To my mind, it still looks like something was in contact.

Can you remove the foil and show us the inside?
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
It is in contact with the pudding on the inside and exposed to the air on the outside. The pudding is on a china plate so there shouldn't be any electrical activity except from the pudding itself. I should stress that this is a slow reaction, the foil is normal kitchen foil, very thin, and the pudding has been covered in it since the end of December. I first noticed the holes about two weeks ago and they don't appear to be any worse now so I think it's about 10 weeks reaction that has caused this. I'll try to get a picture of the underside of the foil.
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aleghartCommented:
Could be splatter from some other food/liquid in the fridge.  Could be that somebody splashed something that was benign in it's natural form.  As it dries, it becomes concentrated enough to act on the foil.

I once splashed Del Taco hot sauce on the trunk of my car.  No big deal until it started to dry.  As water is removed, an acid becomes more concentrated.  To the point that it will eat through several layers of clear coat and paint all the way down to bare metal.

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arun55555Commented:
any type of acid - vinegar, lemon juice ?
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BigRatCommented:
>>I've also just read that very alkaline solution(pH8,5 or more) will etch or corrode aluminum

Quite correct and this will probably account for the foil's corrosion, particularly in places where the foild was damaged in the first place.

A common thing is to see spots of small lumps of white looking material on aluminium saucepans, particularly those of pure aluminium on gas stoves. This is the result of washing the pan in soapy water (Sodium atoms) and the reducing action of a hot gas flame. The resulting Sodium Aluminate blisters on the bottom of the pan as the hydrocarbons from the soap moleclues are burnt away. It also happens with aluminium kettles. There is far less of this on electric stoves, where the reducing flame is not present.
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CallandorCommented:
Aluminum is mostly resistant to corrosion because it forms an aluminum oxide layer very easily http://corrosion-doctors.org/MatSelect/corralumin.htm, but solutions outside of pH 4-8.5 will degrade it, especially if oxygen is kept away from the surface and it is abraded.
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Paul SauvéRetiredCommented:

Aluminium generally has a high corrosion resistance because its surface is by nature covered with a protective layer of aluminium oxide. The thickness of this layer depends on the surroundings. Aluminium is highly resistant to corrosion in the pH range 4 to 8.5. Above and below these values, aluminium is generally susceptible to attack and corrodes. Therefore, foods with pH values outside the range of 4 to 8.5 and/or with concentrations of chloride, iron, copper, nitrite and nitrate should be evaluated regarding temperature, time and air contact.

Here is where I found this answer after a search on Bing with: "which foods react with aluminium"
Head office: Plus Pack AS - Energivej 40 - DK-5260 Odense S - Denmark - Tel: +45 65 50 60 00 - Fax: +45 65 50 60 20 - Email: admin.dk@pluspack.com - ©
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sublimationCommented:
Hi,

Can I please advise, never leave a fruitcake for a month!!! Should be eaten in around a week, max!.  Hence the mould and chemical breakdown!

Aluminum will dissolve in alkali solutions, sodium hydoxide being the best example (put a ball of aluminum into a solution and it goes as wild as pottasium in water)

Aluminum is a pretty reactive metal, its the super thin oxide layer (aluminuim oxide), that makes it seem stable, once this is gone (rubbed off by stucky cake), the metal will react with water in the atmosphere produce more aluminium oxide thus making the metal thinner, until holes appear.

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sublimationCommented:
(repeated typo) Aluminium :-)
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BigRatCommented:
>>Can I please advise, never leave a fruitcake for a month!!!

Christmas Pudding is not a fruit cake. The things are as heavy as lead, almost indigestible, and usually contain silver sixpences. Once made their sell-by-date is counted in years not months.

Christmas with my in-laws consisted of eating huge amounts of roast turkey, washed down with sherry and wine, the came the pudding with custard. Later in the afternoon we had a couple of mince pies each (same sort of heavy consistancy) with clotted cream. For supper we mostly finished off the rest of the turkey as sandwiches or the mince pies. The same procedure was repeated on Boxing day, but with roast beef.

It is no wonder that Robin has left the pud so long, after just those two days of stuffing oneself you can't look at another pie or pudding for months on end!

Needless to say, what I put on then I never have been able to get off again.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
Two days? I ate Like that all week :7)
the Xmas pudding is usually made a few months before Christmas I don't know why, possibly because it takes about 18-24 hours to boil. there is only a quarter of it left I stopped eating it whon the cream ran out and as BigRat said its hard to regain the enthusiasm for it. I was thinking of resurrecting it for Easter, but it looks like a short cut to alzheimers now.
Fruit cakes surely last don't they? the top section of the wedding cake is kept for the Christening.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
*whon=when - blame the handwriting recogniser.
As promised here are two more pics, one of the inside of the foil (although it is horribly out of focus you can see that the holes go right through) and the other of the pudding specifically where the foil was in contact with it - it looks sot of silvery so I think there is a residue of the metal on there.
In terms of the strength of this reaction, the foil is .0007 of an inch thick measured with a good and tested micrometer and the holes developed over a period of something like two months. We are not looking for a pottasium-like fizz, just a steady decay. I'm not sure how I could have 'damaged' the foil, I certainly never poked it with anything sharp, just wrapped it around the pudding as you can see in the picture in the question. As I understand it I would have had to damage it underneath, while it was in contact with the pudding and excluding all air at the same time, I can't imagine how this could be done if you tried.
Is there a simple test for some of the proposed substances? I don't have access to litmus paper, but I know there are some kitchen ingredients that can be used to test for alkalis and acids, some sort of UI can be made from cabbage I think but I'm not sure how.
 

underside.JPG
pud.JPG
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CallandorCommented:
Tomato sauce and aluminum foil do not go well together: http://www.newton.dep.anl.gov/askasci/chem00/chem00364.htm  As mentioned in the article, it's the acid that affects the foil - perhaps there's a small amount in the pudding?  You can probably get a pH test strip from a hardware store to test for acidity, or try some baking soda (it will react with acid).  Some sweet foods are acidic: http://extension.usu.edu/files/publications/publication/FN_Food_Safety_2008-01.pdf
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sublimationCommented:
Christmus pudding can last a month but that is when its wrapped in an air-restricted/air-tight container. Foil wont do te trick... I think the bacteria from the mouldy pudding are eating away at the aluminium....

I suggest you chuck it all in he bin and go buy a new one form you supermarket.

:-)
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BigRatCommented:
>>I suggest you chuck it all in he bin and go buy a new one form you supermarket.

Now that's a good idea! And invite the Rat to help you eat it all and you won't have to wrap it away in foil for Easter!
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sublimationCommented:
And you'll kill the rats at the same time...
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
Thanks for the throwing it away suggestion. That wasn't really the answer to my question though, I'd already decided not to eat any more of it.
Question is: What has affected the aluminium like this? and can foil be considered food safe?
They banned clingfilm after they found that contact with a fatty surface caused some transfer of carcinogens to the food. I don't think this can have been a very quick reaction either as clingfilm was in widespread use for many years before they discovered the possible health risk.
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sublimationCommented:
Hope your okay after eating some of it...I guess it wasn't today and your still around, so that was lucky.

Many good answers below....

You could ask the best chemist on the planet and he wont be able to tell all the chemicals that were in your sweet dish....Basically, knowing that alkalis remove the oxide layer which makes the aluminuim re-react is the basis of the answer.

You'd need a lab and a few good scientists to establish the exact chemical reactions taking place...
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NovaDenizenCommented:
Maybe a combination of the substance of the pudding, the metal of the pan, and the aluminum foil created a battery, and the current thus induced caused the aluminum to electroplate (http://en.wikipedia.org/wiki/Electroplating) the pudding.  

To make a battery, you just need a chemical source of energy and two dissimilar metals, like copper and steel.  See http://hilaroad.com/camp/projects/lemon/lemon_battery.html

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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
Nova, it's sitting on a china plate. The only metal involved is the foil.
I have two likely sounding and strangely contradicting answers:
Callandor Date:24/03/10 07:31 PM "it's the acid that affects the foil"
sublimation Date:25/03/10 03:29 PM "Basically, knowing that alkalis remove the oxide layer which makes the aluminuim re-react is the basis of the answer."
and one unfounded guess:
sublimation Date:25/03/10 10:46 AM "I think the bacteria from the mouldy pudding are eating away at the aluminium"
It isn't mouldy, you can see from the picture that there is no mould, just a couple of spots of aluminium puddingite stuck to it.
This thing is created from many fruity ingredients and a lot of sugar, fats, syrup and things that are sticky. It is boiled for up to 24 hours. It is preserved. If it was a popular recipe in ancient Memphis then I expect that any samples found in King Tut's tomb would still be edible.
Here is a recipe similar (I can't give away my wife's secrets). Ours is boiled for 18 hours instead of the suggested 7. Please note the instruction to cover with foil. We do the same and once the pudding is decanted onto a plate it is simply covered over with a clean piece of foil, mainly to stop anything landing on it. This is the first year that I have noticed any decay to the foil, we have done this many times before.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
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CallandorCommented:
They aren't contradictory; anything outside of pH 4-8.5 (acids or alkalis) will corrode aluminum.  You just need to determine which one does the pudding fall under.
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sublimationCommented:
RobinD: The pudding was not kept in an airtight container so could well be mouldy with loads of bacteria forming...Microscopic stuff. But you tossed it out into the rubish bin which was a good move.

Hmmm, just thought...What if your wife was trying to poison you sith some sort of corrosive...

:-)
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>tossed it out into the rubish bin
Nope, it's sitting in the kitchen while I try to find a bit of litmus paper. It is not mouldy, puddings like this can go on for years as it is stuffed full of all sorts of sugars which will preserve just about anything and was initially boiled for so long that most of whatever that could feed a mould has been broken down into sugars. It is a good wholesome dish, if you've never tried it then you should and you will understand its nature more.
Things kept in airtight containers have their own problems with anaerobicly happy bacteria like botulism. I am much happier keeping my pudding where I can see it.
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JR2003Commented:
Id throw it away just because ingesting aluminium is dangerous. It is though to cause premature senility. At the very least cut off all the pudding that could contain any of the aluminium.
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lesterpenguinneCommented:
Ok there are several things that eat aluminium:  I can only asume it was something that had an acid or a base.  any number of food stuffs contain enough corrosives to do so, (just think Lemons,Vinegar, vitiman C...)  and if the contaner that you put it in was metal say iron or copperor you had ametal spoon in it  you then created a battery and guess what get eaten... thats right the aluminum.  I also know that aluminium is very reactive to some solutions, for example take some ferric chloride PC board echant and pour it in a aluminium pie plate (do it over the sink as it stains) it eats the aluminum very quickly.  I know I did it once...  
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
I have had some likely answers to my question already. the delay, and I apologise, is because I haven't had a chance to test them yet. If you read the thread before talking about batteries, swift corrosion or food poisoning you will see that those areas have been covered.
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sublimationCommented:
"Things kept in airtight containers have their own problems with anaerobicly happy bacteria like botulism. I am much happier keeping my pudding where I can see it"

No matter how you vehermentally try and tell me it isn't mouldy, any food will last longer in an airtight container.
I had a jar of marmalade that developed mould, that is pure sugar, boiled!...Your dish, which I am sure you said you got rid of, would also go mouldy but because it is wet, you wouldn't see the distinctive mould colours, and its sweetness would mask the tell-tale smell of mould.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
Still not the question. Acids or alkalis outside a certain pH range is probably answer. Still awaiting tests.
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sublimationCommented:
But you have no sample...?  Did she bake another one? (poor she!)


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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>But you have no sample...?  
ID:29145216Author:RobinD Date:31/03/10 12:58 AM  "it's sitting in the kitchen while I try to find a bit of litmus paper"
 
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sublimationCommented:
What is sitting in the kitchen, the aluminium foli? When will I get my share of the points?
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>What is sitting in the kitchen
If you read the post I referred to you will see that I was answering yours and he subject of that post was the pudding.
Your continual assumptions ot the pudding being mouldy and guessing whether I have  eaten any or whether I have thrown it away are confusing the issue. Points will be awarded to the most correct answer and may be shared with any that helped when I have had a chance to do some tests.
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sublimationCommented:
Are you going to get her to bake another? Don't think you can test as you need identical sample...Maybe do a chemistry course, you would learn more chemistry in the time, rather than confuse things with blurred pictures..
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
sublimation, why would I need another? I still have the first one. I have never seen this behaviour displayed before so it is this pudding that possesses the quality I want to test. I don't think I need any identical sample and as I have never seen this corrosive effect before I don't think that baking another will produce anything identical.
If I wanted to do a chemistry course I would have done that instead of asking for expert advice on here, I have had some good answers without having to do a course myself.
If the pictures are too blurred for you it is a bit late to mention it, but I woud have been happy to try to take clearer ones. If you can't help with my question maybe you would do better to just sit back and read the other comments. This is a thread about what substances in foodstuffs could corrode aluminium foil and whether foil is a food-safe covering, not about the general storage of food or suppositions about what may happen if the pudding was eaten.
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JR2003Commented:
The fruit in christmas pudding will contains acid, citric acid from the rind of citrus fruits and malic acids from the other fruit also and vitamin C (ascorbic acid) and also some fatty acids from the suet. The less ripe the fruit the more acidic is it.  In the pudding the acidic fruits are not neutralised with an alkali ingredients but just sweetened with sugar to remove the acidic sharpness. Aluminium usually is non-reactive as it is covered with a thin layer of relatively non-reactive aluminium oxide. I think if the aluminium was damaged\torn and a clean bit of aluminium came into contact in an anaerobic environment that the acids, they would react to form an aluminium salt. I  think that a christmas pudding is acidic.
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sublimationCommented:
"This is a thread about what substances in foodstuffs could corrode aluminium foil "

Well, we don't need the sample really.    Are you 100% sure that the foil wasn't already damaged? Or accidentally exposed to another substance in the kitchen....e.g. You washed something with a type of cleaning chemcal and then having those chemicals on your hand, you touch the foil, or the foil touched it...?

Do you have a picture of the foil when you first wrapped it..?

It may be impossible to resolve this, that is what i am trying to make you think about...
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
sublimation, you have asked more questions in here than you have answered. Most of your questions in that post have already been answered above. I can take a picture of another piece of foil before it is used if you like?
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sublimationCommented:
You have to ask questions to find the answer!

So neither do we have the original foil..  The point of some sort of soap/cleaning fluid is very plausible but you haven't given it any thought.

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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>The point of some sort of soap/cleaning fluid is very plausible
We established fairly early on that the corrosion was due to contact with the pudding and not from an external source. It is food and I do not touch food with chemicals or traces of them on my hands. Neither the pudding nor the underside of the foil was touched by hand it is sticky and greasy. Sections of the pudding were removed using clean kitchen utensils and reheated individually before eating. The foil was replaced as soon as the portion of the pudding had been removed.
I think JR2003 has a point with "In the pudding the acidic fruits are not neutralised with an alkali ingredients but just sweetened with sugar to remove the acidic sharpness." and so if I can test acid in the pudding then I will expect acids to be the answer.
Still looking for litmus paper or an alternative.
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sublimationCommented:
I think this is pretty floored without original samples...I say try and recreate it...Maybe put the foil over the new cake in a seperate room so we are sure you didn't splash it with something, wait a few days till it starts to rot... Then you can test the pH with litmus paper
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>wait a few days till it starts to rot
Please carefully read all of the thread above before you comment again.
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sublimationCommented:
The rotting process will start soon, doesn't mean you couldn't eat it!  Bacteria multiply so there will be some the moment you take it out the oven!  Follow my instructions and I think you will have a valid test bed!
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
sublimation, Why are you containing to talk about eating rotting food when that is not any part of the issue?
If you have nothing of value to add to this thread then please stop posting in it.
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sublimationCommented:
Dear, RobinD.

Eating the rotton/fresh cake has nothing to do with its pH, so I am pretty bemused as to why you do not seem to be taking any of my points seriously. Your reference to anaerobicly activity, is merely trying to show-off some scientific terms and was used to refute the fact that every chef in the world would use an airtight container to keep cakes fresh, sugar or no sugar.

If the cake decomposed into an acid, why didn't all the foil dissolve...this is one of many questions that you haven't really demonstrated valid response for.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>If the cake decomposed into an acid, why didn't all the foil dissolve
I don't know. I didn't suggest an acid and I didn't know acids had an affect on aluminium so I don't think it is up to me to be explaining the results. The foil is still mostly intact as you can see from the first picture.
My original question was "What can there be in the pudding that has affected the foil? And does this mean that aluminium foil is not a food-safe covering?"
I have not taken much notice of your comments that fall outside answers to that. I am not looking for a lecture on food storage or disposal. The more recent of your posts seemed to continuously ask for my wife to cook another pudding as you seem to be under the impression that the original is lost. You misunderstood something quite important there and it is quite likely that you missed some other details as well.
I have no interest in recreating the action, just simple answers to what might be in the pudding, the one in the picture at the top, not any other. I am interested that the aluminium corroded because I didn't think it did. As it does I wonder how safe it is as a food covering product. I am waiting until I get a chance to test for acid or alkali as these are the two most likely suggestions that I have already. Cooking another pudding and storing it airtight, open or frozen will not help me find a universal indicator capable of identifying the pH of a pudding sample and so I am waiting to find a way to test and I have already apologised for the delay.
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JR2003Commented:
Aluminium is quite reactive but aluminium oxide is not. As soon as aluminium is exposed to air containing oxygen it will react to for a thin protective layer of aluminium oxide. If there was something that could prevent the reaction with air, e.g. grease, then something else, e.g. an acid, would have the opportunity to react with the aluminium.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
thanks JR, we have already done that right up the top.
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sublimationCommented:
Dear, RobinD.

Your points are very valid...One way of looking at the question, from a different perspective is this:

We (the developed world and undeveloped) have been wrapping all sorts of foods containing all sorts of ingredients (sweet, sour, salty, sticky, wet) in Aluminium foil for about half  a century....So...somebody (e.g you wife's grandmother), may have told her friends back in the 1900s.."oooh, never wrap you tarts in Aluminium foil because it decomposes", and he friend would have replied, "oooh, yes, I noticed that too".....And then, 5 years later, a company, e.g. 3M would have made a foil that is called "Foil that doesn't crumble when you put sweet food in it")...

My point is, if something you put in your pudding was dissolving the foil, then that must be a cooking ingredient never used by mankind before...Which is why I say, you could probably have inadvertently splashed something (non-edible, e.g. oven cleaner) onto the foil...hence the small speckled holes. And which is why I said, maybe your wife tried to poison you.

What you could have done instead of posting blurred pictures, is list ALL the ingredients you put into the pudding...

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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>never wrap you tarts in Aluminium foil because it decomposes
That is the second part of my question. The instructions on the side of the foil packet (and no, it is probably a different packet now) say "This foil is suitable for wrapping food to be kept in a refrigerator. Do not store food in a metal dish covered in foil. Never re-use foil."
The pud wasn't in the fridge and if lifting the foil, cutting a piece of pudding off and then replacing the foil constitutes re-use then I am guilty on that count as well. But, there is no mention on the packet of the length of time that something can be stored in it, nor any limitations on use such as acidic foods etc.
My wife only uses foodstuffs purchased from the local supermarket. The corroded areas are only where the foil is in contact with the pudding and there is only a quarter of the pudding remaining, that's why I discount external splashes as a cause. I have said that I cannot list all the ingredients and I also said that if you had trouble with the pictures you should have said so before. You have missed several times the strong hints that I need a way to test the pH of the remaining pudding.
 
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sublimationCommented:
SO...get your wife to bake another (under controlled conditions), wrap in foil under controlled conditions and you have a test-bed...This is a science forum and science is about re-testing to reproduce results..(If your wife can be bothered)
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
"This is the first year that I have noticed any decay to the foil, we have done this many times before."
So I don't see the need to try and recreate the initial conditions. I just want to know what substance is in this pudding not any other.
 whether my wife can be bothered cr not is not relevant. Try and keep to science or the thread will get deleted.
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sublimationCommented:
"This is the first year that I have noticed any decay to the foil, we have done this many times before."

Sounds like you must have accidentally spalshed something on the foil then...?
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JR2003Commented:
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JR2003Commented:
and this:
http://electronics.howstuffworks.com/battery2.htm
somehow I don't think putting any food in direct contact with aluminium is a good idea unless it is just wrapping it for the bin.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
Without opening those links I see the word battery in all of them. if you want to know why I'm not opening them refer above.
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sublimationCommented:
"This is the first year that I have noticed any decay to the foil, we have done this many times before."

Sounds like you must have accidentally spalshed something on the foil then! And I undersand that there is no other logical explanation.
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sublimationCommented:
JR2003: RobinD will only refer to what he thinks the answer is, don't know why I bother...He effectivly, almost subconciously, answerd a valid point about splashing something on the foil to make it decay. He admitted that he's made the same cake many times, wrapped it in foil and it didn't ever decay....
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
To all, I said way up above that I believe I have my answer. Since then the thread has been muddied with all kinds of suppositions and me having to repeat information I have already given several times. I am doing it again now. If you want to help or get this closed faster, then read my comment two above here.
this is getting too long and off topic to be of much use to anyone now so I might ask for a deletion.
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JR2003Commented:
Ig you're prepared to spend £1.44 you can get some litmus paper delivered from ebay:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=330396941673
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JR2003Commented:
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
thankyou JR, that has answered a question first asked in my 5th post in this thread.
I can now wait until the elderberries and roses grow or buy a red cabbage if I can get one for less than the price of some litmus paper.
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sgvillCommented:
is it possible that the foil just got stuck in a few places were it was touching and it tore, not corroded?
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
look at the picture at the top and also the one of the uncovered pudding. A tear would leave a clean edge, these are pitted. The pudding shows signs of silvery colour in places but as a residue not  as small pieces.
I have acquired a small red cabbage so when I get a chance I will try to make something to do some tests with.
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sublimationCommented:
RobinD: If you intend on getting litmus paper, you can close this thread! Surely you can afford £1.44...

When you do aquire some and stick it against a new pudding (give it a couple of days for decomposition to begin), you will find that the paper will turn sticky and dark brown.....

Still not understanding the pictures...one has foil with little pieces of pudding on it...The other is the pudding with stuff on it...Maybe that was icing sugar or flour coming off the rolling-pin...
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sgvillCommented:
This site seems to go with the acidic/salted/spiced answers: http://www.foodsafetysite.com/consumers/faq/index.html?m_knowledgebase_article=185
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JR2003Commented:
sgvill,
The article  http://www.foodsafetysite.com/consumers/faq/index.html?m_knowledgebase_article=185 doesn't seem to mention premature senility or memory loss as a danger of eating the aluminium. Public bodies don't seem to want to recognise that aluminium can do these things:
http://www.dailymail.co.uk/news/article-499670/Water-poisoning-victim-took-life-inquest-hears.html
I don't know why?
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sgvillCommented:
Maybe they forgot? Or maybe it's because despite 50 years of research, a statistical link between aluminum and alzheimers has yet to be shown?  But, either way, it's not really relevent to the question posted.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
72 posts is way too many.
I have given up trying to explain the situation over and over to people who will not understand.
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sublimationCommented:
your the giving up type! Hmmm...Don't see why you couldn't accept any of the points above...You even said youd wrapped pudding in foil hundreds of times before Without it rotting over night...which is why I say it got contaminated.  maybe make another pudding next easter then!
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Paul SauvéRetiredCommented:
On March 30 I posted the following comment:
Aluminium generally has a high corrosion resistance because its surface is by nature covered with a protective layer of aluminium oxide. The thickness of this layer depends on the surroundings. Aluminium is highly resistant to corrosion in the pH range 4 to 8.5. Above and below these values, aluminium is generally susceptible to attack and corrodes. Therefore, foods with pH values outside the range of 4 to 8.5 and/or with concentrations of chloride, iron, copper, nitrite and nitrate should be evaluated regarding temperature, time and air contact.

Here is where I found this answer after a search on Bing with: "which foods react with aluminium"
Head office: Plus Pack AS - Energivej 40 - DK-5260 Odense S - Denmark - Tel: +45 65 50 60 00 - Fax: +45 65 50 60 20 - Email: admin.dk@pluspack.com - ©

pH < 4: very acidic & pH>8.5: very basic So unless you do a chemical analysis the individual ingredients that are present, you just wont know!
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
>On March 30 I posted the
I see that comment posted on Mar 24th.
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Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndAuthor Commented:
The results are in. I boiled the red cabbage and reduced the water slightly until it was a deep bluish purple in colour.
Tested with vinegar a sample of the indicator turned red, with sodium bicarbonate a different sample  turned green. A sample of the Xmas pudding stirred around in it caused a colour change to red, not such a bright red as the vinegar and the change was slower I imagine that this means the acid in the pudding is not as strong as vinegar.
In most of these pictures I have left a couple of drops of unchanged indicator so you can see the difference in colour.

indicator.JPG
indicator-vinegar.JPG
indicator-bicarbsoda.JPG
indicator-pudding.JPG
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