Milling by-products
The main by-products of rice are rice husk or hull, rice bran, and brewer’s rice.
- Rice husks or hullsare generated during the first stage of rice milling, when rough rice or paddy rice is husked.
- Rice bran is generated when brown rice moves through the whiteners and polishers. When paddy is hand-pounded or milled in a one-pass Engleberg steel huller, rice bran is not produced separately but mixed with rice hulls.
- Brewer’s rice is separated produced when milled rice is sifted.
Rice husk
Fig. 1. Paddy grain (left) and its products after husking.
What is rice husk and what are its major products?
The rice husk, also called rice hull, is the coating on a seed or grain of rice. It is formed from hard materials, including silica and lignin, to protect the seed during the growing season. Each kg of milled white rice results in roughly 0.28 kg of rice husk as a by-product of rice production during milling.
Common products from rice husk are: solid fuel (i.e., loose form, briquettes, and pellets), carbonized rice husk produced after burning, and the remaining rice husk ash after combustion.
One hundred kilogram (100 kg) of paddy rice will generate approximately 5−10 kg of bran. Rice bran is a mixture of substances, including protein, fat, ash, and crude fiber. In many cases, bran contains tiny fractions of rice hull, which increases the ash content of bran. Bran composition is largely dependent on the milling process.
Brewer’s rice is often used as ingredient for beer brewing, hence the name. In rural areas, brewer’s rice has a variety of uses including ingredient for rice flour and rice noodles.
