Canned foodstuffs: Do they fall under the category of the unknown, or is it permissible to sell them?

Question:
Honorable Shaykh, may Allah grant you success. He says: Do canned foodstuffs fall under the category of the unknown, or is it permissible to sell them?

Answer:
No, they are known and regulated; there is no gharar (excessive uncertainty) in them. Their types are known, and their duration and shelf life are known. There is no gharar, and they are not sold except in this condition: if you open them, they spoil, so they are not sold except in this condition. Yes.