Anyone who's seen the documentary Supersize Me is likely to remember Morgan Spurlock's food decay experiment (video below).
Placing McDonald's burgers, a fish fillet, and a chicken sammy into separate glass containers, he let them sit unrefrigerated on a countertop for 10 weeks to "give you an idea of how this food is breaking down in your body."
The test group comestibles showed almost no decay, and armchair food detectives were quick to point to preservatives as the culprit.
But further examination revealed that fat and salt could be the actual ingredients keeping Mickey D's grub pristine well beyond the point when real food breaks down.
Slate.com e-mailed Marion Nestle, chairwoman of New York University’s food studies program, for an opinion. She said that, lacking preservatives, "really a lot of" sodium propionate would be necessary for the Happy Meal embalming process.
So, eliminating salt as the primary factor, America's most ubiquitous fast-food indulgence is really protected from the elements by high levels of fat, which keep moisture at a minimum and make a burger or fries less susceptible to mold.
But for that extra layer of decay-proofing, the food—fries in particular—is also drenched in salt, "something we've been using as a natural preservative for the last 2,500 years," says Slate's Riddhi Shah.
Not that these findings are a health benefit bonanza. At least preservatives had us envisioning life eternal. Fat and sodium are sure to do the opposite.