Jennifer Lovdahl, co-owner and operator of a chiropractic facility in Alaska wanted to demonstrate to her patients on unhealthiness of a McDonald's meal. She stored it for six years to see how it would change. The results? It didn't!
Lovdahl posted pictures of a Happy Meal she purchased on Jan. 8, 2010. The chicken nuggets and fries appear to be fairly unchanged apart from maybe losing some color.
‘Fast food is not healthy, but, its chemical content isn't the reason for its pristine-looking state.’
Apart from Lovdahl, Serious Eats writer J. Kenji López-Alt conducted a much more thorough experiment in McDonald's burgers.
López-Alt's research strongly supports the idea that McDonald's burgers, and similarly-sized homemade burgers, don't rot because of dehydration. Mold and bacteria grow only when there is moisture, and he found that 93% of the burger's moisture was lost in the first three days, so "unless mold gets a chance to grow within that time frame, it's pretty much never going to grow."
López-Alt also notes that, according nutrition labels, a McDonald's burger bun doesn't contain any more preservatives than an average loaf of bread you would find in a supermarket.
But, Dr. Gary Nabhan, director of the University of Arizona's Center for Regional Food Studies points out that "dessication" or an extreme state of dryness, coupled with low oxygen, are two key factors that can reduce immediate spoilage in any food.
According to him, the food has dehydrated before any visible deterioration could occur.