Eli5: how does canned food last so long while the can is sealed? Does it use preservatives?
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Generally no preservative is needed. The concept of canning is to not have to use preservatives though. By making the food completely sterile and then sealing it in an airtight can there are no bacteria or air which can cause the food to go bad. So a can of food can stay good even after years of storage.
However there is quite a bit of difference between various types of food. Some can go bad without bacteria or air by the chemicals in the food themselves degrading over time. It may just be a change in taste or texture and still be perfectly fine to eat but this is something you want to avoid anyway. So it is not uncommon to use some type of preservatives in canned goods. But a lot less then in other type of food. And a lot of these preservatives is things you not always think of as preservatives. For example brine, canola oil, table salt, vitamin-c, vinegar, etc. Things like you might add to the food anyway.
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