When it comes from the growing field, each grain of rice is enclosed in a tough hull, or husk, which must be removed. Underneath is the nutritious whole grain, which may be brown, reddish or even black, depending on the color of the bran layers. All rice may be eaten at this stage, but most are processed further.
Under the hull are the bran and germ which are high in vitamins, minerals, oil and various phytonutrients proposed to have health-benefits. Rice at this stage is 100% whole grain.
Remove the bran and germ and what remains is the endosperm, the white rice enjoyed throughout the world. To replace some of the nutrients lost in milling, most North American processors apply a thin coat of thiamine, niacin, iron and folic acid to milled rice to produce what is known as enriched rice.
Whole-grain rice (sometimes called brown rice): longer cooking time; more fiber; high in vitamins, minerals, oil and various phytonutrients; shorter shelf life which can be extended using cool storage temperatures.
Milled rice: shorter cooking time; enriched to restore nutrient value; longer shelf life.