Optimisation of the alkaline peroxide pretreatment for the delignification of rice straw and its applications

Alkaline peroxide pretreatment for the delignification of rice straw was optimised by varying the concentrations of H2O2 and NaOH and changing the temperature and duration of the pretreatment. Changes in the lignin content, content of total carbohydrates and weight loss were measured during the pretreatments. Maximum delignification of 62% was obtained by pretreating rice straw at 50°C for 5h with 1.5% (w/v) NaOH and 1% (v/v) H2O2, The preferential loss of hemicellulose and lignin from the straw resulted in an increase in the cellulose content of the insoluble residue after pretreatment from 47% (untreated) to 67.79% (treated). The product of this treatment is characterised by having higher cellulose digestibility than untreated rice straw. It also has use as a carbohydrate source in ruminant feed since the in‐vivo digestibility by the cow increased from 56.85 % to 76.54% (P < 0.001). The treated rice straw could also be used for commercial process such as the generation of Single Cell Protein. Growth of Sporotrichum pulverulentum on treated rice straw gave a protein product of 24.41 % as compared to 3.8% on untreated rice straw.