Mass balance and energy content for non-carbohydrate insoluble solids after pretreatment and washing and enzymatic hydrolysis. aResidual solids = (recorded total dry solids left unhydrolyzed) - (dry glucan and xylan in the solids). bEnergy content = 0.9 × residual solids (g) × 25.4 kJ/g. This is done by assuming 90% of the total residual solids are lignin and the remaining 10% has negligible heat value. The heat value of lignin used (25.4 kJ/g) was as reported.