BACK TO PREVIOUS PAGE Rye Flour Rye Flour. The finely ground product obtained by milling the rye cereal (q.v.). There are three general grades of rye flour that are classified, according to their color and degree of extraction (q.v.), into white patent, medium straight grade, and dark low grade. In that order, they exhibit progressively higher values in protein (q.v.), ash (q.v.) fiber (q.v.) and lipid (q.v.) contents.