So why don't fast food burgers and fries decompose in the first place? The knee-jerk answer is often thought to be, "Well they must be made with so many chemicals that even mold won't eat them." While that's part of the answer, it's not the whole story.
The truth is many processed foods don't decompose and won't be eaten by molds, insects or even rodents. Try leaving a tub of margarine outside in your yard and see if anything bothers to eat it. You'll find that the margarine stays seems immortal, too!
Potato chips can last for decades. Frozen pizzas are remarkably resistant to decomposition. And you know those processed Christmas sausages and meats sold around the holiday season? You can keep them for years and they'll never rot.
With meats, the primary reason why they don't decompose is their high sodium content. Salt is a great preservative, as early humans have known for thousands of years. McDonald's meat patties are absolutely loaded with sodium -- so much so that they qualify as "preserved" meat, not even counting the chemicals you might find in the meat.
To me, there's not much mystery about the meat not decomposing. The real question in my mind is why don't the buns mold? That's the really scary part, since healthy bread begins to mold within days. What could possibly be in McDonald's hamburger buns that would ward off microscopic life for more than two decades?
As it turns out, unless you're a chemist you probably can't even read the ingredients list out loud. Here's what McDonald's own website says you'll find in their buns:
Enriched flour (bleached wheat flour, malted barley flour, niacin, reduced iron, thiamin mononitrate, riboflavin, folic acid, enzymes), water, high fructose corn syrup, sugar, yeast, soybean oil and/or partially hydrogenated soybean oil, contains 2% or less of the following: salt, calcium sulfate, calcium carbonate, wheat gluten, ammonium sulfate, ammonium chloride, dough conditioners (sodium stearoyl lactylate, datem, ascorbic acid, azodicarbonamide, mono- and diglycerides, ethoxylated monoglycerides, monocalcium phosphate, enzymes, guar gum, calcium peroxide, soy flour), calcium propionate and sodium propionate (preservatives), soy lecithin.
Great stuff, huh? You gotta especially love the HFCS (diabetes, anyone?), partially-hydrogenated soybean oil (anybody want heart disease?) and the long list of chemicals such as ammonium sulfate and sodium proprionate. Yum. I'm drooling just thinking about it.
Now here's the truly shocking part about all this: In my estimation, the reason nothing will eat a McDonald's hamburger bun (except a human) is because it's not food!
No normal animal will perceive a McDonald's hamburger bun as food, and as it turns out, neither will bacteria or fungi. To their senses, it's just not edible stuff. That's why these bionic burger buns just won't decompose.
Which brings me to my final point about this whole laughable distraction: There is only one species on planet Earth that's stupid enough to think a McDonald's hamburger is food. This species is suffering from skyrocketing rates of diabetes, cancer, heart disease, dementia and obesity. This species claims to be the most intelligent species on the planet, and yet it behaves in such a moronic way that it feeds its own children poisonous chemicals and such atrocious non-foods that even fungi won't eat it (and fungi will eat cow manure, just FYI).