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My trailer (in Florida) gets extremely hot. My canned items are warm to touch. Should I just store the unopened cans in the fridge or pour in bags/containers and freeze?

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  • this is not a food safety issue, just leaving the cans, refrigerating them, or opening and freezing the contents are all safe. This is only a quality issue, and your best bet is probably to refrigerate the cans.
    – Esther
    Jul 6, 2023 at 18:48
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    Can you express, in C or F, how hot is your "extremely hot"?
    – Mołot
    Jul 6, 2023 at 23:40

7 Answers 7

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If you can keep the temp below 85 °F (30 °C) you should be fine. There is no harm in placing your cans in the refrigerator, and I think this would be your best bet if you have the space. I would not freeze the can, as that might compromise the integrity of the can itself.

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  • fixed...apologies!
    – moscafj
    Jul 5, 2023 at 22:34
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    Frozen water expands. That will compromise the integrity of the can.
    – RonJohn
    Jul 6, 2023 at 18:09
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The relationship (reactions doubling for every 10°C = 18°F ~=20°F) is pretty universal. For this reason I keep certain chemical items in a fridge. That means that lifetime is halved for every 10°C increase in temperature. So if the rating is 2 years at 25°C the life will be 6 months at 45°C = 113°F.

If you can't keep them cool maybe consider adjusting the BB date to a lower lifespan (the challenge with that is you don't always know when they counted as the beginning).

USDA says

"high temperatures (over 100 °F) are harmful to canned goods too. The risk of spoilage jumps sharply as storage temperatures rise. In fact, canned goods designed for use in the tropics are specially manufactured."

In fact, optimal storage temperature is more like 10 or 15°C (50 or 60°F), cool but safely above freezing.

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    You don’t know what the original life is, but if you know how much time is left when you put it into storage, you can calculate what 1/4 the time left is (and assume that it was stored at a reasonable temperature before you got it)
    – Joe
    Jul 6, 2023 at 16:39
  • @Joe Excellent point. Jul 6, 2023 at 19:08
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    +1 for USDA link and tropics. The more you know.
    – paulj
    Jul 6, 2023 at 19:09
  • "if the rating is 2 years at 25°C the life will be 6 months at 35°C" That's a quarter of the lifetime, not a half.
    – Flater
    Jul 7, 2023 at 4:53
  • @Flater wow. my bad. fixed. thanks. Jul 7, 2023 at 11:42
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Harold McGee actually had an article on canned goods in the now defunct magazine Lucky Peach. Luckily, it’s also been posted to medium: On Cans

The relevant part is:

The trouble with aging canned goods is that it takes years to get results. However, we can take a hint from manufacturers, who often accelerate shelf-life tests by storing foods at high temperatures. A general rule of thumb is that the rate of chemical reactions approximately doubles with each 20-degree rise in temperature. Store foods at 40 degrees above normal—around 100 degrees—and you can get an idea of a year’s change in just three months.

I suspect that manufacturers calculate their ‘best by’ dates based on non-ideal storage, so it’s possible that they are still applicable, but actively ‘warm’ might be a stretch, so I would recommend paying attention to the ‘best by’ dates. (Although, tastes vary; McGee commented that he preferred some aged things better than when still young)

Depending on how much you’re storing, and if the humidity is low enough, you might be able to rig up a pot-in-pot cooler. I would avoid keeping the cans completely wet, though, to reduce the risk of both rust and the labels coming off.

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  • "40 degrees above normal—around 100 degrees" means that 60 (presumably Freedom) degrees is normal. That's absurd.
    – RonJohn
    Jul 6, 2023 at 18:07
  • This is Florida. Humidity is never low enough.
    – Mark
    Jul 7, 2023 at 2:41
  • @RonJohn Are you really not aware that different parts of the world experience different temperature norms? 60 F is not an absurd temperature to keep your house at. Jul 7, 2023 at 19:56
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    @RonJohn the sentence you refer to is a quote from McGee, and was not written in response to this question. 60 F is not unusual for a cellar (especially if regarded as a yearly average), or some other place which meets the description of a "cool, dark place", frequently recommended by manufacturers of goods with long shelf life, or used by restaurant owners who also store cheeses, wine, etc.
    – rumtscho
    Jul 7, 2023 at 22:33
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    @rumtscho this isn't 1943; most people live in cities or suburbs, and don't have root cellars.
    – RonJohn
    Jul 8, 2023 at 5:13
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The inside of these cans is sterile, so freezing won't do much good. It will slow down the chemical degradation of the contents but this is almost irrelevant unless you plan to store the cans for decades after their best-by date.

We generally refrigerate/freeze to stop bacteria from spreading/multiplying in or on our food (and potentially producing toxic wasteproducts). Since there are exactly 0 bacteria in a can of food, this major benefit is wasted

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    One danger of freezing canned foods is the can could rupture or crack, which could cause problems later if the can is thawed and not immediately used. At high temperatures, degredation of food quality can happen much faster than you might expect. Shelf-stable food storage life is generally based on the assumption it will be stored in cool dark conditions. High heat can reduce shelf life from years to months or even weeks.
    – barbecue
    Jul 5, 2023 at 19:09
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    It strikes me that even if a can didn't detectably rupture, the internal lacquer (or tin) layer might be compromised: at that point the same warnings as about dented cans apply. It probably wouldn't be too bad while a can was left frozen, since there wouldn't be liquid water inside. But thawing and then leaving for an extended period... I'm not saying it's definitely unwise, but is probably best avoided if possible. Jul 6, 2023 at 11:17
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Never freeze unopened canned food, as the ice may rupture the can from the inside, in the same manner it breaks water pipes in the winter. Freezing will also change the food texture and make it more mushy, severely decreasing organoleptic qualities.

Put them into refrigerator, but make sure the temperature stays above 0° C.

People saying that food in cans is sterile are missing the point, because most food still slowly degrades via means different from microbial action.

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Check that there is nothing inside the trailer (I believe this is what we'd refer to as a caravan in the UK) that is actively generating heat, e.g. a fridge or freezer due to not venting to outside.

On reflection, it's only necessary to cool the cans by a few degrees so the first thing I'd investigate is whether there's some spot, probably low down and away from an outside wall, which is substantially cooler than everywhere else and would make a good place for a food cache. My suspicion is that you've got storage lockers fastened to outside walls, probably including some above a work surface which will suffer from the "hot air rises" rule.

If you have some location which is relatively cool, consider whether you can make it cooler by having a fan on a timer which blows night-time air through it, say midnight to 9am. You could further capitalise on this by putting in some of those gel packs which "keep hot things hot and cold things cold".

Irrespective of political outlook, one has to admit that we're going through (or entering into) a hot phase, so there's no point in making it even minutely worse by running appliances which aren't strictly needed. There's also the cost of running them to consider: a timed blower is going to be vastly cheaper than space in a fridge.

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It is a little silly to store canned food in a refrigerator. It does very little to extend the shelf life of the food inside. Unless your average ambient temperature is something like 130 degrees Fahrenheit your canned goods will be just fine on a cupboard shelf. Even then the canned food should be fine for years.

"It is best to store unopened commercially canned foods in a cool and dry place (such as in a cupboard)." USDA

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