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Old 24-March-2008, 03:12 AM
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Thumbs down like a Fridgerator?

i was thinking, what if you had like a vacuumed sealed fridge, that sucked out all the air and left it viod..or w.e.

and you had two doors one was the freezer and the other was like an oven! but nor really an over....but it kept your hot food hot..

bc i was thinking if you could heat the vacuumed sealed "oven" to a temp that killed germs (or w/e) but still didn't char the food...then..could you store it for longer? and since its vacuumed sealed wouldn't the heat transfer better and it wouldn't cost as much as you think it would, to run it?


there should be an Altered smiley

off topic.
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Old 24-March-2008, 04:59 AM
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you mean, an oven surrounded by a vacuum layer? like a thermos flask?



w.e and w/e= what ever
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Old 24-March-2008, 06:15 AM
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Originally Posted by Frog march View Post
you mean, an oven surrounded by a vacuum layer? like a thermos flask?



w.e and w/e= what ever

um no i mean the intire inside vaccume void of air. bc i hear air corodes

and yes w.e and w/e mean what ever
and bc means because
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Old 24-March-2008, 07:08 AM
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If you kept the food constantly hot, it would be nasty after a few hours. Try it with something in your regular oven. It will dry out. Even if it can't dry out because of the seal, I imagine it would still be nasty.

Sucking the air out of the fridge is a great idea. That's the logic behind vacuum sealers: remove the air. Probably, the reason it's not done is because you'd have to have a powerful motor attached to your fridge, and your seals would have to much stronger. As it is now, there is little or no pressure gradient between the inside of your refridgerator and the air in your kitchen. This would add a lot to the cost of a refridgerator. And it wouldn't be significantly better than storing your leftovers in Tupperware, or even plastic bags.

I like to use plastic produce bags. See if you can talk your grocer into selling you a roll of them. They store like a roll of paper towels, and there's thousands on a roll, so it takes a few years to run out. Put your leftovers in them, and push the air out of them and then tie a knot. This keeps your food it a pretty good vacuum.
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Old 24-March-2008, 08:51 AM
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i just thought that you would have to pressurize the fridge every time you opened it hahaha. so it couldnt be a fridge.

it would have to be a deep freeze.
but then it couldnt be hot...

so could you put frozen(already frozen) foods into it and then suck out the air?

it would keep it frozen wouldnt it?

even after you stop using the electricity (bc the way im looking at it is that after you suck alot the air outta it, then you will have a like,,,cork? to seal it off and....yeah)

i shouldnt have put that in parentheses
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Old 24-March-2008, 08:59 AM
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A problem with your idea of sucking out the air is that it would make the refrigerator work worse than one with air in it.
In a fridge, the things are cooled because the air moves between the food that has to cool down and the cold fins in the back, transporting heat from the food to the fins.
Without the air, cooling is only through radiated heat (and evaporation in things that are not packed airtight, freezer burn much?) which is a lot less effecting.
This means that it's useless for cooling things down fast enough to keep bacteria from growing like crazy.
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Old 24-March-2008, 09:20 AM
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Originally Posted by HenrikOlsen View Post
A problem with your idea of sucking out the air is that it would make the refrigerator work worse than one with air in it.
In a fridge, the things are cooled because the air moves between the food that has to cool down and the cold fins in the back, transporting heat from the food to the fins.
Without the air, cooling is only through radiated heat (and evaporation in things that are not packed airtight, freezer burn much?) which is a lot less effecting.
This means that it's useless for cooling things down fast enough to keep bacteria from growing like crazy.

well what about just a deep freeze? like i mentioned in the post right before yours. could you get food and pre freeze them to w/e temperature required(for best results) then place them in the deepdreeze, maybe on a block of ice(idk).
then suck the air out....

would the "product" retain its frozen state for longer?

and if it would then you would be able to put regular items in there as well, like apples you want too keep fresh for a long period of time?
like...with the apples you would put them in the fridge and let them get the temp they usually get...then put them in the deep freeze. you wouldnt even need a divider. bc the vacuumed space would be sufficient enough?


most of what i typed were secretly questions.

yeah...
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Last edited by johnathan : 24-March-2008 at 09:39 AM. Reason: spelling
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Old 24-March-2008, 01:56 PM
Nick Theodorakis Nick Theodorakis is offline
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If I use biological samples as an analogy to food (probably not unreasonable, since what makes food go bad is similar to what makes biological samples degrade):

We have three kinds of frozen storage:

(1) Regular freezer temperature (-20C); however, we prefer frost-free freezers because automatic-defrosting freezers cycle their temperature. Some compounds may be sensitive to moisture so they also get put in a dessicator (sealed container with a drying agent), but you wouldn't want that for food. Others may get tightly sealed to prevent water from sublimating -- this might be useful to food storage, and heat-sealable bags haev already been invented for this purpose.

(2) Ultra-low freezers. These are typically at -80C. They draw a lot of current (typically have a dedicated circuit), and moreover usually need 220V, and they are very expensive. And also noisy (constant hum of a big compressor). Biological samples that may go off after a few months at -20C will typically last years in one of these. I would guess the shelf life of meat kept at -80C would be close enough to forever for your purposes, if it was kept from drying out.

(3) Storage under liquid nitrogen. This is about -190-ish C. Also tends to purge oxygen from samples. Storage is pretty simple -- basically a big Dewar (thermos bottle) but it does need to be refreshed periodically.

There are a couple of things that make food go bad. One is microbial growth. Freezing retards growth (not necessarilly killing it). Cooking kills bugs, too, but if you want to guarantee complete sterilization food may get cooked more thoroughly than you may find it acceptible for some items. Pressure cooking cooks things at a higher temp than the boiling point of water, and thus may destroy spores that are heat-resistant (which is why autoclaving is favored for laboratory and medical sterilization). Irradiation will also destroy microbes; some people (not me) have a problem with irradiated food, and for home use it would be impractical.

The second thing that makes food go off is fatty acid oxidation. This is what makes fats go rancid, and happens independently of microbial growth. This can be countered either by preventing oxygen from reaching the sample, or by adding anti-oxidants, or both.

If I wanted to hypothetically keep food for a long time at higher temperature (room temp or slightly warm) and money was no object, I would cook it, vacuum seal it after purging oxygen from the sample, and also adding anti-oxidants, then irradiate the bejeebers out of it. I probably wouldn't keep it at cooking temperature, because heat will continue to break down biological molecules.

Or maybe just use one of those Slaver stasis boxes from Larry Niven's Known Space universe.

Nick
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Old 24-March-2008, 02:04 PM
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It would be cheaper to buy food that's already canned.
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Old 24-March-2008, 02:22 PM
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It would be cheaper to buy food that's already canned.
you say "already" canned like i was planning to can it.
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Old 24-March-2008, 03:13 PM
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He says it because that if you want vacuum sealed food, that is a much easier way to do it.
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Old 24-March-2008, 04:45 PM
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you say "already" canned like i was planning to can it.
I think he said it because Nick's description is a fair go at describing canned food, except for the radiation part.
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Old 24-March-2008, 09:53 PM
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Quote:
Originally Posted by johnathan View Post
um no i mean the intire inside vaccume void of air. bc i hear air corodes

and yes w.e and w/e mean what ever
and bc means because
It's cheaper just to revert to canning or a Vac 'N Seal then boil the pouches for a while.
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Old 24-March-2008, 09:58 PM
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Quote:
Originally Posted by Musashi View Post
He says it because that if you want vacuum sealed food, that is a much easier way to do it.
a vacuumed sealed frozen food??

bc i changed the idea since the OP :P

now its a deep freeze! hahaha

check a post of mine up there somewhere?
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