The dry matter content (DM) of the solid straw fraction after wet oxidation (filtercake) is measured by drying at 105°C overnight. The procedure for SSF is as follows: 250 mL flasks are loaded with 100 ml substrate with either 17 g DM or with 8 g DM. The substrate is adjusted to pH 4.8 with 6 mol/L of NaOH. After pH adjustment, 15 FPU/ g DM of Celluclast (Novozymes mixture of endo — and exo-glucanase) is added together with 0.20 ml of Novozym 188 (|3- glycosidase) per ml Celluclast using sterile conditions. The flasks are shaken at 50 °C with 120 rpm for 24 hours during the pre-hydrolysis. After the pre-hydrolysis, 10FPU/ g DM of Celluclast and 0.20 ml of Novozym 188 (|3-glycosidase) per ml Celluclast are added together with 1-4 g/L of Turbo yeast and 0.8 g/L of urea and the pH value re-adjusted to 4.8 with addition of NaOH. The flasks are sealed with glycerol yeast locks and incubated at 37°C with shaking at 120 rpm. During SSF, the flasks are weighed to measure ethanol production with respect to time, and after the SSF termination a sample of the supernatant is analyzed by

HPLC (High Performance Liquid Chromatography, Shimadzu) with a Bio-Rad Aminex HPX87H column and 0.6 mL/min flow of the eluent (4 mmol/L of H2SO4) at 63°C for ethanol and monosaccharides (Thomsen et al., 2009).