Several pretreatment techniques such as alkaline pretreatment, dilute acid hydrolysis, and fungal pretreatment have been used for ethanol production. The acid pretreat­ment was the best pretreatment for ethanol production followed by alkaline and fungal pretreatment.

16.5.1.1 Alkaline Pretreatment

Generally, the alkaline pretreatment has been used for delignification. The removal of lignin is needed for cellulose that is available for enzymes. Delignification has been tested by using different concentrations of hydrogen peroxide at different pH for vari­ous time intervals. However, 2 % hydrogen peroxide has been used at alkaline pH for the removal of lignin from sugarcane biomass (Dawson and Boopathy, 2008). Lignocellulosic biomass cannot be saccharified by enzymes without pretreatment. Proper pretreatment would reduce the lignin content of sugarcane straw. Hydrogen peroxide can play an important role for the delignification of sugarcane straw. Krishna and Chowdary (2000) reported that alkaline peroxide pretreatment was more effective for delignification of leaves. Alkaline pretreatment has an advantage for by-products which are released during lignin degradation by alkaline peroxide (Gould and Freer 1984). Suhardi et al. (2013) reported that alkaline pretreatment at pH 12 was the opti­mum for maximum ethanol production in variety of cane L 79-1002.