Yes, but when archaeologists rediscover those same Twinkies a thousand years from now, they will still be edible (unless the radioactive cockroaches have gotten to them first). This is not just urban legend - I saw it on "Family Guy". So you know it's true.
"Compared with a bunch of carrots, a package of Twinkies, to take one iconic processed foodlike substance as an example, is a highly complicated, high-tech piece of manufacture, involving no fewer than 39 ingredients, many themselves elaborately manufactured, as well as the packaging and a hefty marketing budget. So how can the supermarket possibly sell a pair of these synthetic cream-filled pseudocakes for less than a bunch of roots?" - Michael Pollan, You Are What You Grow, nytimes.com, 22 April 2007.