The definition of "fresh" has been twisted a bit recently. We previously wrote about a gas-flushed sandwich that stays fresh for two weeks. How about a sandwich that stays fresh for two years? The BBC recently aired a fascinating video on the development of a two-year-old sandwich for the U.S. Army as part of the show After Life: The Strange Science of Decay (video not embeddable).
A challenge to creating the sandwich was to figure out how to make sure bacteria couldn't breed. The trick was to cut off the oxygen supply. In order to do that, an "oxygen scavenger" -- essentially a packet with iron shavings -- is inserted into the package. Mmmm iron shavings, so tasty.