Fig. 2

The influence of mechanical size reduction on the enzymatic hydrolysis of washed alkaline sulphite steam-pretreated lodgepole pine substrate. Enzymatic hydrolysis was conducted at solids loading of 5% for 48 h with a cellulase enzyme loading of 35 mg protein per g cellulose. The alkaline sulphite steam pretreatment was performed with 16% Na₂SO₃ and 2% Na₂CO₃ at 160 °C for 20 min followed by a second step of steam pretreatment at the temperature of 210 °C for 10 min. The mechanical size reduction was performed with a lab-scale grinder. The control sample was pretreated with 4% SO₂ based on the dry biomass and steam pretreated at 200 °C for 5 min