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I accidentally put my unopened canned yellow fish tuna into the fridge for about a day. I took it out and put it in the pantry. Is it safe to eat?

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    As long as you didn’t freeze it …
    – Michael
    Apr 13 at 17:47
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    @Michael What hazard does freezing cause?
    – MonkeyZeus
    Apr 14 at 13:43
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    @Michael that might ruin the taste (but of canned tuna??? really?) but no health hazard Apr 14 at 15:05
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    @MonkeyZeus: I imagine the expansion of freezing water could break the container. Maybe less of an issue with a metal container, but certainly a problem if it were e.g. glass.
    – Michael
    Apr 14 at 15:15

4 Answers 4

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It is perfectly safe. You've got a pasteurized product that is shelf stable while the can remains sealed. All you did was make it colder for a few hours. This is not a safety issue at all.

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    I wonder if there's any food that becomes less safe by cooling it down in a fridge. I'm not sure the fact that it's sealed or pasteurized makes any difference
    – Aequitas
    Apr 13 at 7:02
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    @Aequitas I was essentially trying to point out that it was completely safe to begin with. If the can was previously opened, without information on the conditions of that scenario (how long, under what temperature), one could not make the claim of safe practice. So, the sealed can is an important factor. We have lots of questions on this site about how (or if) refrigeration extends shelf life. I was intentionally trying to be clear. So, it is not that cooled food becomes less safe, but that it is sometimes assumed that cooling food extends shelf life, which is not always the case.
    – moscafj
    Apr 13 at 10:49
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    @Aequitas It's possible an open can of tuna (or anything else) might be made less safe in a fridge, due mainly to the moisture causing the can to rust. (A closed can may also rust in a moist fridge, but if the rust is only on the outside, you're generally okay. And one day is certainly not long enough for that to be an issue.) Apr 13 at 13:51
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    @DarrelHoffman both the temperature and absolute humidity inside a fridge are typically lower than the surrounding environment. Thus I would expect it would still be safer against corrosion in the fridge than out.
    – Rick
    Apr 13 at 17:49
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    @JohnnyJP that makes them less pleasant, but not less safe
    – Tristan
    Apr 15 at 12:19
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There are only a rather small handful of cases where refrigerating some type of food is potentially problematic. They generally fall into one of four categories:

  • Certain lipids congeal or solidify when they get down to typical refridgerator temperatures. This can cause them to separate out if they are part of a soup or sauce (often forming a scum-like layer on top of the other liquids if stored in bulk), or to solidify and cause things to stick together. Usually this can be solved by reheating and mixing, but in some cases it can completely ruin a sauce or gravy.
  • Similarly, how much salt and other solids you can dissolve in a liquid is dependent on temperature, and chilling the liquid can cause such solids to crystalize or precipitate out out of the solution. This is more often an issue when putting things in the freezer, and can almost always be solved by reheating and mixing, but is a serious pain when it happens.
  • A major component of perception of flavor has to do with olfactory perception of volatile (in the proper scientific sense of the term) compounds in the food. These compounds evaporate and disperse less readily at cold temperatures, so chilling certain foods can have a very significant impact on their perceived flavor. Famous examples of this include various varieties of wine and sake, which often taste noticeably different when served chilled compared to being served room temperature. In general, just warming the food up again will resolve this.
  • Starch recrystallization, the primary process which causes bread and similar foods to go stale, happens more rapidly at typical refrigerator temperatures (as compared to room temperature, it actually happens even more rapidly at colder temperatures, up until you get to the freezing point of water, where it stops completely). This means that things like bread stored in a refrigerator go stale faster than they do if stored at room temperature (but, on the flip side, they generally don’t become moldy). Unlike the others, this process cannot be completely reversed.

None of these are really safety issues. All three except the last one might affect canned tuna, but I would think it’s unlikely to be a significant issue given that canning it in the first place already has a pretty big impact on the taste.

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  • Chocolate in the fridge is a famous example. Fat and Oil separate from sugar which crystalizes, showing white patches. this happens over time anyway, and the only backdraw is in taste. Apr 16 at 16:37
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Lower temperatures result in less chemical reactivity and therefore less spoilage. In addition, the refrigerator, in principle, makes the space dry. All of these help improve the storage of food.

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    Yes: generally speaking, cooler temperatures are always safe (though freezing may degrade consistency). However, the bit about “dry” is rather dubious: it's true that water condenses at the cooled back wall and thus makes the air drier, but because there is no active air circulation this isn't really effective at “making the space dry”. In fact, what happens in practice is rather that every time the fridge is opened, there's a brief circulation of warm, wet air, and that humidity condenses on all the cold stuff in the fridge, so putting stuff in the fridge to keep t dry is not a great idea. Apr 13 at 13:46
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    This answer doesn't really address the question about canned food.
    – Johannes_B
    Apr 13 at 15:18
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    @leftaroundabout most household fridges are self defrosting. They work by using active air circulation to bring the air to the evaporating coils where the water will freeze/condense outside the fridge, and then drip off and evaporate into the surrounding environment while the compressor isn't running.
    – Rick
    Apr 13 at 17:53
  • @Rick at least in Europe, “active air circulation” is not common at all in household fridges, unless you mean something different than I think. Fridges are just nearly-hermetic boxes with a cold back wall. They do have a hole at the bottom which I suppose allows condensed water to evaporate again, but it's certainly not actively removed from the fridge. Perhaps air circulation fans are common in the US, I don't know. (On this side of the pond we have the stereotype of huge and absurdly energy-hungry American fridges...) Apr 13 at 20:22
  • @leftaroundabout in the parts of Europe I’m familiar with, refrigerators with active air circulation aren’t all that unusual, including in non-US-style refrigerators. This isn’t new either, I’ve had one for twenty years. Apr 14 at 8:00
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I don't believe that tin is used in the canning process these days, but I have heard this question before, and think that it may arise because of the use of tin in the past.

Tin and tin-coated steel has been used in the past in the canning process. Tin has several different crystaline structures that are stable at different temperatures. The atoms in the allotrope of Tin that is formed at 13.2C (56F) are packed less efficiently that normal tin, and thus the tin can crumble and corrode. This can cause damage to the tin can that could lead to food spoilage. This process is known as Tin Pest.

Tin itself is not very toxic, so any direct tin contamination would probably not be a concern. So in your case, even if your tuna can was made with tin, you'd be OK, and the short amount of time invloved means that spoilage would also not be a concern.

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