Help with my science fair topic?

alrighty, it's good old science fair time, and i need help with a project idea and how i should test it. i literally looked everywhere for a topic, but none of them suited my interest. i am in 8th grade (honors) so technically 9th grade. i was thinking about experimenting with bread, and how to make it last longer. is that a good thing to do as a 8/9th grade project? why or why not?