Shironuka (white rice bran)

Shironuka (白糠, literally "white bran") is a type of rice bran produced when brown rice is polished during sake production. Specifically, it refers to bran produced when the rice polishing ratio (the percentage of the grain remaining after polishing) is around 75%. Among the other classifications of bran, bran produced at a rice polishing ratio of less than 90% is called akanuka (赤糠, red bran), less than 85% is called chunuka (中糠, middle bran), and less than 75% is called tokujonuka (特上糠, special bran) or tokushironuka (特白糠, special white bran). Shironuka is the part that contains the outer layer and germ of the rice. Because their presence allows the flavor and nutrients of the rice to influence the sake, it plays an important role in the quality and taste of sake.