McDonald's Burgers Don't Rot! Preservatives or Moisture Loss?

One alternative explanation could be the loss of moisture in the buns and patties during grilling. Bacteria cannot grow without enough water, whether in the food itself or the environment, so the burger would not rotten under such conditions. This explanation was proved true by J. Kenji López-Alt's experiment, where both home-grind beef burgers and McDonald's counterparts grew mold after being stored in an air-tight plastic bag for seven days. But that still could not eradicate my concerns about the quality of McDonald's food...