Science Fair Project for my Daughter

Last year she did a science fair project in which she took a plain burger and fries from McDonalds, Burger King, Wendy's and a Homemade. She observed them and kept them in the same kind of plastic containers for over a month to see the breakdown of each - Homemade was incredibly disgustingly moldy with multiple colors of mold - absolutely gross, McDonald's literally looked the same, just a little drier - BK and Wendy's each had a slight change, but for the most part all the fast food had too many preservatives so they did not mold. Very eye-opening. Thank you all again for all your help. Her teacher liked her initial reports and predictions with this number project.