I once had a few cans of pears and condensed soup from the store that, um, spent the winter in my stationwagon. The bag got sort of lost under all the other nine million things back there Boy was I ever glad there wasn't meat or produce in that bag! Anyhow, this was in Ohio and temps got down well into the -20s F several times -- and I doubt it was any much warmer in my car at those times. I don't remember the exact count, but when I noticed the cans in February or so, some cans had split somewhat and oozed all over <eeuww> and others appeared to be sealed perfectly fine. Although, I have to say I chucked the whole lot of 'em in the trash so I cannot comment on their eating qualities.
I'm not sure what that means but it's sort of a data point for you
I do not know the scientific answer, however when I took a food handlers safetly class through our county offices the instructor stated they would most likely make you sick and should be tossed. Something to do with acidity changes blah blah blah ( LOL I was 16 what do you expect ) Ok its been a really long time since then! I would not take the chance with my family I guess is what I am trying to say.
All right, you made me curious! Here is an answer I found online:
Are canned goods that are frozen inside the jar safe to eat?
If home or commercially canned foods freeze, they are still safe to eat IF the seal (or seam of the can) is not broken.
When commercially canned foods freeze, the food inside expands and the can may bulge or even burst. Throw cans in this condition away, without tasting (don't even give it to your dog). Even if the can is not bulging, there may be microscopic openings in the seams due to stress.
Thaw frozen canned goods slowly; a refrigerator is an ideal place to thaw such foods. Commercially canned foods can be placed on a tray or plate to check for leakage from the seams that may not be apparent. If any leakage occurs, discard the food.
Use canned goods that have frozen as soon as possible (providing seals and seams are not leaking) as quality will deteriorate quickly.
Starchy foods may curdle (separate) when frozen -- thawing and heating should correct this problem.
As an added precaution, boil all low acid foods 10 to 20 minutes, depending on the food, before tasting.
If produce canned at home was processed in jars made for freezing as well as canning, the frozen jar may be placed directly in the freezer and kept there until used. Keep in mind that quality, especially texture, will be affected. Therefore, this food should be used as soon as possible.
Any food that looks or smells bad should be discarded so that humans and animals cannot eat it.
To prevent loss of food, home and commercially canned goods should be stored in an area where they will not freeze. While an unheated porch or garage might be acceptable during a normal Missouri winter, these areas will not offer enough protection from freezing during the sub-zero temperatures that Missouri sometimes has. If jars must be stored where they may freeze, wrap them in newspapers, place them in boxes and cover them with more newspapers and heavy blankets.
Barbara Willenberg, Nutritional Sciences, University of Missouri-Columbia