hot air vs cold air

[moxion]

Hi there,

 

When one pours hot food (just cooked hence with no bacteria) in a tupperware and seals it immediately, the lid gets sucked-in as the air inside gets colder (cold air is less voluminous than hot air).

I believe this is not similar to air-vacuum sealing (no air at all).

 

However, can one use that "air-shrinking" process as a preservation method like air-vacuum? (since the hot air that shrunk was bacteria-free).

 

Many thanks to those who will bring the light to that matter!

[chemkid]

I say no. First of all, your going to have to get your food awfully hot to render it organism free. Also the air in there is not organism free. Nor is the container itself. Perhaps if you sterilize the container as well and do it in a clean room. Or you could get a whole bunch of smoke detectors, break them open, pull out the americium and use that as a gamma radiation source and sterilize the whole thing with that. I have scalpel blades gamma radiation sterilized. Or you could get a short wave (germicidal) UV lamp, though you might need to mash the food for that. Then again you could probably just get one of the little vacuum sealers, it would probably be simpler.

 

chemkid

 

PS Please don't try the smoke detector one, its illegal and you'll end up on the evening news

[swansont]

Similar to canning foods, I'd expect

 

http://www.canningpantry.com/home-canning-articles.html

[moxion]

I was trying to figure out methods a food factoy has got to protect the shelf life of a sealed product. So yes, the product would be pasteurized, which would kill all germs of course.

In that case, what's the difference in terms of shelf life preservation between air-vacuum sealing (no air) and the air-shrinking method I describe (clean shrunk cold air since it would be done in a clean environment)?

[NeonBlack]

Please don't listen to chemkid. I think what you're trying to do will work fine as long as your jars and utensils etc are all clean.

 

Depending on the food, I think that most of the air would even be displaced by water vapor when the food is hot so there would be very little air in the jar after it cools.

[moxion]

Do you mean that hot air (vapor) "vanishes" as it turns cold, creating "emptiness"?

[NeonBlack]

By "vanishes" I mean turns into water, but yes.

I was born in the country, and my grand-parents used to can fruit. Simply heating it and sealing it creates a pretty good vacuum and the contents last at least several years.