Nutritional Impacts of Different Whole Grain Milling Techniques: A Review of Milling Practices and Existing Data1 The majority of whole grain flour is produced using modern milling techniques, usually with steel rollers, in which a batch of grain is separated into multiple millstreams, sifted, and recombined. In some cases constituent millstreams are purchased and combined by a supplier or end user to achieve a reconstituted whole grain flour or meal with desired functional, safety, and nutritional properties. In a very small number of cases whole grain flours are stone-ground, with the grain kernels crushed between rotating stones. Data comparing single-stream milling and multiple-stream milling with recombination do not show any strong advantage for either milling method. The separation of millstreams, in fact, allows highly labile brans and germs to undergo a stabilization treatment to make them less susceptible to rancidity—the net result of which is greater safety, stability, and nutrient retention. Data comparing use of stones and steel rollers in milling, in most cases, show improved nutrient and dietary fiber retention and greater protein availability in grains such as barley when steel-roller mills are used. The AACCI Whole Grains Working Group supports increasing whole grain intake through the use of intact whole grains and grains milled with stones and steel rollers in single-stream milling, multiple-stream milling where streams are recombined at the mill, and multiple-stream milling in which whole grains are responsibly reconstituted. |