I have never used #10 cans of anything, but have always had a concern about what happens to the contents once you open a can. Will the contents "go bad" once opened, requiring you to eat a can empty once it is opened? If that is the case, seems to me that you could get really tired of having the same thing every meal 'til gone, and then it is gone for good. No variety. Do the cans come with plastic snap-on lids to "seal" the can once it is opened???