Their only differences may be in coarseness and protein content. Insoluble fiber content is higher than in white flours. Bran is the outer layer of the wheat kernel that is removed to make white flour. It is used primarily for diabetic breads, or mixed with other nonwheat or low-protein wheat flours to produce a stronger dough structure. Gluten flour improves baking quality and produces high-protein gluten bread.
Wheat germ is the heart of the wheat kernel.
It comes flaked or in a coarse meal, either raw or toasted. Wheat germ adds a pleasant, nutty flavor to baked goods and increases their protein and mineral content. It is the most oil-rich and therefore the most perishable part of the wheat. At the supermarket, wheat germ is found in vacuum-packed jars that must be refrigerated after opening. 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.