Bread staling is referred to as deterioration in structure, texture, and flavor characteristics during storage - the crust of staled bread becomes soft and leathery, its crumb becomes firm, and its fresh baked flavor is lost. Firming of bread has been the most important parameter in the study of bread staling. As discussed elsewhere in this book, several theories have been proposed to explain why bread firms during storage. It seems that there is no one mechanism that can fully explain the staling phenomenon. No matter what mechanism, be it loss or redistribution of water, change in water property, starch recrystallization, change in gluten protein networks, or interactions between gluten protein and starch granules, bread firming will involve changes in molecular mobility of the bread system, which can be assessed by nuclear magnetic resonance (NMR) techniques. 1-4 .