Wheat bran, the outer layer of grains of wheat, is a by-product of the flour-milling process. Although almost tasteless, fresh bran contributes a mild earthy flavor to muffins and other baked goods and is added to recipes along with flour to boost the fiber content and overall nutrition. Unprocessed wheat bran, which has not been toasted, is also packaged as miller's bran. Look for it in the cereal section of supermarkets or in natural-foods stores. Because bran is high in natural oils, it should be stored in the refrigerator to maintain freshness.