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Thread: Hot air vs cold air

  1. #1 Hot air vs cold air 
    New Member
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    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!


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  3. #2  
    Forum Masters Degree bit4bit's Avatar
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    Well when you put the hot food in the container, you will also trap some air in it too from the surrounding environment, and even though the bacteria within the food will have been killed/denatured, there will still be some in the air, that has been trapped inside. Vacuum sealing is different because it removes all the air.


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  4. #3 Re: Hot air vs cold air 
    Moderator Moderator Janus's Avatar
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    Quote Originally Posted by 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!
    This is how home "canning" is done.
    You cook the food you are planning to can. You sterilize the jars you are going to use in a pressure cooker (this allows to to heat the to well above the boiling point of water). You take the heated jars, pour the still hot food into the jars and then place a metal lid(also sterilized) with a rubber seal on the jars. These are held in place by a threaded ring. The lids are made with a slight convex bulge to them. As the jar cools, the small amount of trapped air shrinks pulling in on the lid, if you did everything right, eventually the convex bow will "pop" into a concave dip. Hearing this "pop" tells you that the jar has sealed properly.
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  5. #4  
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    Are both methods (air-vacuum and air-shrinking) similar in terms of effectiveness? Which one gives the best preservation method (all things equal)?
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