Ash is the inorganic residue remaining after high-temperature incineration of wheat flour and similar products, often part of the proximate analysis. This rapid instrumental analytical method is used to predict the ash content of wheat flour using near-infrared (NIR) spectroscopy, eliminating the time-consuming steps of incineration and cooling. There is a very high correlation between flour ash and bran cellulosic content (see reference), and it is likely NIR calibrations are associated with cellulosic components of bran fragments in the flour, rather than ash components. Mineral (ash) content of bran is about 20 times greater than that of endosperm; thus, ash content is used as an indicator of the degree of bran separation from the endosperm. See Method 39-00.01 for NIR guidelines.