Rice husk is often interpreted as waste material or leftover material from the rice milling process. Processes that have an impact on running slowly, not only disrupt the surrounding environment but also interfere with human health. At every mill, we will always see piles and even mountains of husks that are getting taller and taller. Currently, the use of rice husks is still very little, so that the husks are still a waste material that disturbs the environment (Aziz, 1992).
Rice husk consists of a hard layer that includes a kariopsis which consists of two halves called the lemma and palea which are interlocked. In the rice milling process, the husks will be separated from the rice grains and residue or milling waste (Aziz, 1992).
The structure of rice husks has four layers, namely the outermost epidermis which is covered with the epidermis, Scelerenchyma, Spongi parenchyma, and the innermost epidermis. Of the four layers above, rice husk has silicon that is dominant in both layers of the epidermis which functions as a hardener and protector of the grain against fungi (Aziz, 1992).
Chemical properties of rice husks are generally composed of organic and inorganic components. Components include carbohydrates which are dominated by cellulose and hemicellulose. Crude protein in rice husk is about 3% and lipid 0.039-2.98% (Primo et al, in Luh, 1980). The amount of pure lignin in rice husk is around 19.20-24.47% (Lenzio in Luh, 1980). The vitamins contained in rice husks include thiamin, riboflavin, and niacin then about 13.2-29.0% of the weight of rice husks are inorganic components such as Fe, Ca, Mg, P, and others are compounds needed in rice growth (Houston in Luh, 1980).
Husk is classified as biomass that can be used for various needs such as industrial raw materials, animal feed and energy or fuel. From the rice milling process, about 20-30% of the grain is usually obtained. The use of husk energy aims to reduce expenditure costs for fuel for farmers' households. From the rice milling process, about 20-30% of husks are obtained, bran between 8-12% and milled rice between 50-63.5% of the initial weight of grain data. Husk with a high proportion can cause environmental problems (Houston in Luh, 1980).
Bibliography:
Azis, S.A, Krisantini, Winarso D. Widodo and Aris Munandar. 1992. Study on the Utilization of Husk, sawdust, bark and peanut shells as a medium for growing plants in containers. IPB. Bogor.
