From the processing plants where cow manure gets ground into meat to the chemistry labs that create fast food flavors such as a "smoky, grilled taste," the story behind every perfectly round patty hamburger and golden fry is something the fast food industry would prefer you not know.

A slew of books and movies over the last decade have revealed the gnarly business of fast food, and it's anything but enticing.

Not Just Food

Any recount of fast food horrors would be remiss without a collection of sordid restaurant tales. Bugs, rodents, and unsanitary working conditions are the common pitfalls of making mass-produced food. These war stories shouldn't be surprising, yet they are. Here's a sprinkling gathered from former fast food workers and news reports:

* At a Long John Silver, an employee stirred a bucket of cole slaw with his whole arm immersed so deep that his armpit hair mingled with the shredded cabbage. 
* TV news cameras filmed dozens of rats scurrying around a Taco Bell/KFC in New York City. 
* Former fast food workers say that it's common to blend cockroaches and other bugs into dairy deserts. 
* Inspectors found dead rodents decomposing in a rattrap at a Wendy's in Texas. 
* A customer was served a cup dripping in blood at Hardee's in Florida. 
* A patron, taking a bite into a taco at a Chicago Taco Bell, bit into chewing gum.

Even though people are vaguely aware of these violations, Americans continue to consume vast quantities of fast food. Why? Convenience and price are good reasons, but that doesn't really explain why we eat so much of it. After all, a street vendor could be selling steamed fresh broccoli and spinach for a penny and do less business than a McDonald's does. The obvious reason is that fat, salt, and starches appeal to our palates. But there's more going on than good grease. Excellent frying techniques can't explain the allure of McDonald's fries. In fact, fast food flavor has little to do with the innate qualities of the food-it's all in the additives.

Engineered Flavors

The fast food industry has worked hard to engineer foods that will appeal to our every sense with manufactured flavorings, color, and what's called mouthfeel-the texture, weight, and consistency. In his book Fast Food Nation, Eric Schlosser described how companies-often the same ones that make perfumes-mix the chemicals that give our processed food their flavors. Schlosser lists nearly one hundred chemicals that make up the standard strawberry flavor in a milkshake. The flavoring for proprietors is kept secret. For decades, McDonald's used beef tallow to cook its fries. When the public started to worry about saturated fat, the company switched to vegetable oil, but it continues to use animal products to achieve the same flavor. McDonalds has refused to disclose what other ingredients they use. The FDA doesn't require food companies to list the ingredients in additives, as long as they are Generally Regarded as Safe (GRAS).