Rice is the seed of a monocot plant Oryza sativa. Rice is one of the major crops grown throughout the world. As a cereal grain, it is the most important staple food for a large part of the world's human population. World production of rice has risen steadily from about 200 million tonnes of paddy rice in 1960 to 600 million tonnes in 2004. Consequently, rice industry produces several by-products, e.g. rice husk, rice hull, rice husk/hull ash, rice bran.