Eli5: how does canned food last so long while the can is sealed? Does it use preservatives?
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Canned foods have had all the bacteria that could spoil it killed during the canning process. The process uses heat which is why there’s not raw ingredients from cans.
The heat kills the bacteria and also denatures enzymes that cause the food to break down.
Additionally when something is heated it expands. Canned things are canned hot so when it cools there is a relative vacuum. So there’s very little air for bacteria, and they were killed during the heating process.
This is then sealed in a closed environment, like a can, and that’s how it’s kept stable.
Edit:
To add to the preservative question- Sometimes.
Home canned things don’t need them, but companies can put things in there to make the food look better, have better texture, or flavor since the food is essentially being cooked to hell the first time. There needs to be a certain pH range and salinity to stop botulism but if the food falls within the safe parameters it’s k.
Some foods have preservatives like SPAM but that’s sodium nitrate which is also in cured meats like bacon or ham.
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