Starch, dextrins, cellulose, pentosans, and various free sugars make up the carbohydrate content of wheat. Milling removes almost all the cellulose as well as most of the pentosans. Most fiber in wheat is in the cellulose. Damaged starch granules (altered during the process of milling) play an invaluable role in structural development in leavened breads and batters. In yeast doughs, the amylase enzymes attack damaged starch first, producing sufficient simple sugars (cryohydrates) to feed the yeast during fermentation. Damaged starch also affects the formation of dextrins during baking and the moisture level of the finished product. Ratios exist for the optimum level of damaged starch found to be beneficial in flour, directly correlating with the protein content of the flour. Flour contains a small amount of sugar; melbiose is converted by an enzyme in yeast, melbiase, to produce simple sugars directly available to the yeast as food. The pentosans in flour may amount to 2 to 3 percent, primarily in the tailings or end runs in milling. Pentosans can aid in producing bread with a higher moisture content and reduced staling.