Enhancing Enzymatic Digestibility of Wheat Straw by Ethanol Cooking Pretreatment

Ethanol cooking is an important process for the fractionation of biomass components. This work evaluate the effectiveness of sulphate acid catalyzed ethanol cooking pretreatment on enzymatic hydrolysis of wheat straw. The wheat straw samples, which were impregnated with 1.0% sulphate acid for about 12 h at room temperature, were submitted to ethanol cooking pretreatment. The influence of both pretreatment temperature and time on total gravimetric recovery, hemicellulose sugar, recovery yield of hemicellulosic-derived sugars, recovery yield of cellulose, yield of enzymatic hydrolysis of cellulose was investigated. The results indicated that total gravimetric recovery decreases while solubility of hemicellulose and enzymatic hydrolysis yield of cellulose increases as the pretreatment severity increases. Pretreatment condition of 170°C temperature and 30 minute residence time resulted in the highest total gravimetric recovery, 71.3%. The susceptibility of the pretreated wheat straw was greatly affected by the temperature and time of pretreatment. The maximum glucose content of 71.2%, enzymatic hydrolysis yield of 69.3%, recovery yield of cellulose of 25.8%, and recovery yield of hemicellulose of 66.9%, occurred under the condition of 190°C temperature and 60 minute residence time.