They are in the same way any canned good is. If you boil it, the can is likely to warp slightly and allow water in, also things like plastic liners and other chemicals can leech into your food, you generally aren’t supposed to cook food inside the cans they come in.
Canned food is literally pasteurized in said can, while submerged in water at temperatures slightly lower than 100 °C. The whole reason to put food in cans is to create an airtight atmosphere that can be thermally treated with hot water. This kills certain spores (mainly botulinum) which is why canned food has a very long shelf life.
It’s still not correct to cook the food that way, but not because of the reason you made up.
Boiling a can can absolutely open up a can. Pasteurizing happens below boiling point and for much shorter time, not enough time to change the pressure inside the can.
Boiling it for a long time can evaporate liquids and cause the pressure to build up and split a can open or warp it enough to open. It’s enough of a concern that condensed milk generally ships with a warning because of it.
Note that it won’t generally be the giant pop/explosion of cooking a can directly in flames.
In fact, cans of condensed milk specifically bursting when boiling was a big enough concern a few years ago because of a tiktok trend making caramel that way that there articles and videos of people fuckin it up
Wait are these cans not watertight?
They are in the same way any canned good is. If you boil it, the can is likely to warp slightly and allow water in, also things like plastic liners and other chemicals can leech into your food, you generally aren’t supposed to cook food inside the cans they come in.
Canned food is literally pasteurized in said can, while submerged in water at temperatures slightly lower than 100 °C. The whole reason to put food in cans is to create an airtight atmosphere that can be thermally treated with hot water. This kills certain spores (mainly botulinum) which is why canned food has a very long shelf life.
It’s still not correct to cook the food that way, but not because of the reason you made up.
Boiling a can can absolutely open up a can. Pasteurizing happens below boiling point and for much shorter time, not enough time to change the pressure inside the can.
Boiling it for a long time can evaporate liquids and cause the pressure to build up and split a can open or warp it enough to open. It’s enough of a concern that condensed milk generally ships with a warning because of it.
Note that it won’t generally be the giant pop/explosion of cooking a can directly in flames.
In fact, cans of condensed milk specifically bursting when boiling was a big enough concern a few years ago because of a tiktok trend making caramel that way that there articles and videos of people fuckin it up
https://ca.sports.yahoo.com/style/why-cautious-making-caramel-canned-131502700.html