I've noticed an increasing amount of the canned foods I buy are coming with pull ring pop tops rather than requiring the use of a can opener. This seems to be limited to soups so far but I imagine other types won't be far behind. Anybody care to hazard a guess as to whether this will reduce storage times? I also wonder whether severe heat/cold cycles would affect them more over the long term.

I realize some foods (kippers, spam, and others) have been sealed in a similar fashion for years. I just wonder if we are giving up some shelf life and safety for the sake of convenience. Or maybe I am concerned over nothing. Maybe somebody who does some canning could chime in?

Regards, Vince