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For as long as I remember, I was always told (and I was always so sure), that minus 18 degrees Celsius is an optimal temperature for storing frozen products for really, really long. Months usually and in case of certain types of meat and fish, even up to one year.

Some other sources, that I recall, but can't cite right now, said that in minus 18 degrees Celsius most (if not all) products can be kept until at least "best before" date.

Some time ago I went to a one of Polish shops around me and I was shocked to find this infobox:

enter image description here

It basically says, that in minus 18 degrees Celsius I can store all products up to one month (so not "many months" and not "really long"), with exception of ice cream (which even at this temperature can't be stored for longer than a week+).

And minus 24 degrees Celsius* I can store most frozen products "many weeks". Which leads me to a conclusion that under no home-applicable* circumstances I'm not allowed to store frozen food for "many months" or "really long".

What am I missing? Is above presented table correct?

* not mentioning, that none of fridges / freezers, that I use is able to run at minus 24 degrees Celsius temperature and to be honest -- I have never heard about any home-targeted device, that is able to achieve this temperature.

Community
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trejder
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    Are you concerned with food safety or food quality? Also, related question: http://cooking.stackexchange.com/questions/41104/what-temperature-to-freeze-meat-at-to-preserve-quality/41106#41106 – Catija Jun 13 '16 at 21:23
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    Also, [this](http://cooking.stackexchange.com/questions/21068/how-long-can-i-store-a-food-in-the-pantry-refrigerator-or-freezer/21069#21069) should pretty much answer your question... if you're interested in food **quality**, however, that's an entirely different story. – Catija Jun 13 '16 at 21:27

3 Answers3

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-24°C will usually be chest freezers, not uprights.

-18°C seems to be generally considered to be cold enough that even new-old-stock mammoth would still be safe, albeit a little dry. The only caveat is auto-defrosting systems in some freezers, they raise the temperature periodically (check the documentation for your model of freezer).

rackandboneman
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There is not one magical temperature that is optimal for all frozen foods. Even after manufacturing and before the product ends up in your shopping cart, the products have all been stored at a minimum of 3 different temperatures of cold warehouse storage.

dpollitt
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Not today, you probably will not find a freezer that will achieve -25 C. Most all freezers now are self defrosting which means they go thru a thaw cycle several times a month that raises the temperature above freezing for a short period of time to defrost the refrigeration coils. This process warms the air inside the freezer and increases temperatures of the outside of frozen product enough to cause deterioration or freezer burn after the product refreezes. You are right in saying there are not any modern home freezers that can do this. Probably because most all of them are self defrosting except some chest type. I have a RCA Whirlpool chest type freezer that is over 40 years old and has been freezing at -20 below zero Fahrenheit which is about - 30 Celsius since it was new and is still working great. They do not make things like they used to. Bottom line is if you want to keep food for long periods of time, the colder the temp and not using a self defrost unit is the best way. Putting it in vacuum seal bags also keeps it better and fresher even longer.

Leroy
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