Fig. 3

Sugar yields after steam pretreatments of spruce wood chips at different severities with and without explosion. a Enzymatic cellulose digestibility. Cellulose conversion to glucose is expressed as % of pretreated biomass content. b Yields of glucose and mannose dissolved in the pretreatment liquor, expressed as % of raw biomass content. c Total glucose and mannose yields from the combined operations of pretreatment and enzymatic hydrolysis, expressed as % of raw biomass content. d Total sugar yield of glucose plus mannose from the combined operations of pretreatment and enzymatic hydrolysis, expressed as % of raw biomass content. Pretreatment conditions: T = 235 °C, t = 2.5–20 min, Δp explosion = 30 bar; hydrolysis conditions: 1 %w/w cellulose, 60 FPU g⁻¹ cellulose