It's been done, repeatedly. And the answer is there's no difference between McDonald patties and homeade patties. Any small cooked ground beef patty is unlike

It's been done, repeatedly. And the answer is there's no difference between McDonald patties and homeade patties. Any small cooked ground beef patty is unlikely to mold; it dries out too fast. Larger burger patties will mold, as will smaller ones if kept in the right conditions.