Eli5: why do certain refrigerated products require us to consume all once opened? Why can’t we eat some and refrigerate it again to consumer it later?

Question

Eli5: why do certain refrigerated products require us to consume all once opened? Why can’t we eat some and refrigerate it again to consumer it later?

In: 24

Answer 1

I’ve only seen packaging say “after opening, keep for limited time” but that generally means more than a week