Improved enzyme efficiency of rapeseed straw through the two-stage fractionation process using sodium hydroxide and sulfuric acid

Two-stage fractionation process using sodium hydroxide and sulfuric acid was conducted to remove lignin and hemicellulose from rapeseed (Brassica napus) straw. This process consists of two stages; using sodium hydroxide, the first stage solubilized 35.54% of lignin and increased the glucan content in the treated solid from 32.86% to 38.13%. The second stage solubilized 85.85% of the lignin and 91.56% of the XMG (Xylan + Mannan + Galactan) into hydrolyzate. After the two-stage process, merely 2.53% of glucan and 3.81% of XMG were lost due to excessive decomposition. Despite the reduction in enzyme loading by 50%, the enzymatic digestibility with the two-stage treated straw was approximately 23% higher than that of the single stage acid fractionation process.