Fig. 1

Sugar recovery (glucan and xylan) and lignin removal after pretreatment. NaOH–ethanol pretreatment was performed under the following conditions: 1.63% NaOH, 70% ethanol, 66 °C, 3.18 h; 1.90% NaOH, 70% ethanol, 69.8 °C, 1.00 h; and 1.46% NaOH, 70% ethanol, 70 °C, 2.19 h for pith, rind and whole stem, respectively. NaOH pretreatment was performed under the same conditions, except that 70% ethanol was not included