Abstract: Reducing sugars can be derived from biomass hydrolysis. The corncob hydrolysis was conducted after supercritical carbon dioxide pretreatment and ultrasonic pretreatment. The effects of pretreatment temperature, moisture content, temperature and time of ultrasonic on the yield of the reducing sugars were emphasized. The result shows showed that the optimum conditions of corncob supercritical carbon dioxide pretreatment were 100℃, 50% moisture content, 30 min and 15 MPa. The optimum conditions of corncob ultrasonic pretreatment were 59 kHz,90 W and 20 min. The pretreated corncob was hydrolysised with 1% dilute sulphuric acid under the condition of 160℃, 40 min and liquid to solid ratio of 50:1. The highest yield of reducing sugars is 39.5% and 38.4%, respectively. Compared with the control sample, the yield of the reducing sugars was increased by 13.3 and 12.2 percent point, respectively.

Key words: corncob, supercritical carbon-dioxide pretreatment, ultrasonic pretreatment, hydrolysis, reducing sugars