Fig. 3

Glucose (a) and xylose (b) yields following enzymatic hydrolysis of alkaline pre-extracted and fed-batch Cu-AHP pretreated hybrid poplar at different H₂O₂ loadings (yields based on composition of alkaline pre-extracted biomass). Triangles represent 120 °C NaOH-EtOH pre-extraction and squares represent 120 °C NaOH-H₂O pre-extraction. Pretreatment reactions were performed at 30 °C for 24 h at 10% (w/v) solids. Particle size was 3–7 mm for pre-extraction and 1 mm for Cu-AHP pretreatment. The final Cu²⁺ and bpy concentrations in the reaction were 1 mM and 2 mM, respectively. Enzyme loadings for enzymatic hydrolysis were 30 mg total protein per g glucan. The data points are the averages of three independent experiments, and the error bars represent ± standard deviations of the means. Circles represent 30 °C NaOH-H₂O pre-extraction from a previous study [13]. Experimental conditions were largely the same as above, except that samples were milled to pass through a 20-mesh screen (0.85 mm) prior to pre-extraction, and a temperature of 30 °C during both pre-extraction and pretreatment, and enzyme loadings of 60 mg total protein per g glucan. The data points are the averages of three independent experiments, and the error bars represent ± standard deviations of the means