Effect of steam-assisted alkaline pretreatment plus enzymolysis on converting corn stalk into reducing sugar
2020
Liu, Chaoqi | Liu, Mengjie | Wang, Ping | Chang, Juan | Yin, Qingqiang | Zhu, Qun | Lu, Fushan
In order to improve corn stalk conversion into total reducing sugar effectively, steam-assisted alkaline pretreatment and enzymatic hydrolysis was studied. This result showed that cellulose and hemicelluloses contents in corn stalk were decreased to 7.01% and 4.41% (P < 0.05), and total reducing sugar yield was increased to 335.09 mg/g biomass (P < 0.05), when corn stalk was pretreated with steam and alkali (0.8% NaOH + 1.2% CaO, W/V) for 1.0 h at a ratio of alkaline solution to corn stalk of 5:1 (V/W), followed by enzymatic hydrolysis at 22.5 FPU/g biomass cellulase for 48 h. The synthetical enzymatic hydrolysis conditions of pretreated corn stalk were pH 5.0, 50 °C, 60 filter paper unit (FPU)/g biomass and 48 h reaction time, in which total reducing sugar yield was 358.97 mg/g biomass (P < 0.05). The further response-surface methodology results showed that the total reducing sugar reached 493.74 mg/g biomass under the conditions of 52.39 FPU/g biomass cellulase, 6599.99 U/g biomass β-glucanase and 40 h reaction time. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and pore structure analyses indicated that steam-assisted alkaline pretreatment plus enzymatic hydrolysis were effective in breaking the crystal structure of corn stalk for increasing total reducing sugar yield.
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