Brown rice flour. Brown rice (or "hulled rice") is unmilled or partly milled rice, Oryza sativa. The process that produces brown rice removes only the outermost layer, the husk, of the rice kernel, which is the least damaging to its nutritional value and avoids the unnecessary loss of nutrients that occurs with further processing. To make brown rice flour, the husk of rice or paddy is removed and raw rice is ground to form a powder. Brown rice is an excellent source of manganese, and a good source of the minerals selenium and magnesium 1. Brown rice flour is gluten free.