system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do bread and milk expire so quickly, when cheese, ranch, and croutons seemingly last forever in comparison?
gpt
Bacteria required a suitable environment to grow. Chief among this is water; they cannot survive if they cannot keep their insides liquid. Croutons are very dry so they are protected that way. Cheese is basically eaten already, but by organisms which leave behind tasty remains. They are often pretty dry too, which makes them last.