Crumb staling is more complicated. Over the years, food scientists have published hundreds of papers on the subject. Many have come to believe the process has to do with starch within the gluten structure. “Starch granules exude amylose during baking,” says Bill Atwell, professor of grain science at the University of Minnesota. Spiderwebs of amylose then attach to the gluten network. As the crumb sheds moisture, these webs stiffen. Some bread manufacturers extend shelf life by adding enzymes that sever these amylose strands, or by way of additives that inhibit starch from interacting with gluten.