Durum flour is finely ground semolina. It is usually enriched and used to make noodles. Either grinding the whole-wheat kernel or recombining the white flour, germ and bran that have been separated during milling produces them. Their only differences may be in coarseness and protein content. Insoluble fiber content is higher than in white flours.
Gluten flour improves baking quality and produces high-protein gluten bread.
The Food and Drug Administration inspects and approves the use of flour treatments and additives that are used to improve the storage, appearance and baking performance of flour. The treatment additives are in no way harmful. There is no change in taste, color, texture, baking quality, or caloric value of flour. Ascorbic acid is now being added to strengthen the flour for bread doughs. No change occurs in the nutritional value of the flour and no harmful chemical residues remain.