4.2 Raw material conditioning

After extraction of juice or grain harvesting, the lignocellulosic residue is chopped, milled, and dried at 50-60 °C to reduce the moisture content to about 10 to 15% (Herrera et al., 2003; Sipos et al., 2009). There are many options to reduce particle size; the most commonly used are hammer or rotary mills. Grinding can be used on both dry and wet materials, and the cost is one of the lowest compared with others methods used for milling biomass. The grinder reduces the particle size to a fine powder by mechanical shearing and this operation can also be made with rotating and stationary abrasive stones (Mizuno et al., 2009).