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Acetone/water oxidation of corn stover for the production of bioethanol and prebiotic oligosaccharides

Katsimpouras, Constantinos, Dedes, Grigorios, Bistis, Perrakis, Kekos, Dimitrios, Kalogiannis, Konstantinos G., Topakas, Evangelos
Bioresource technology 2018 v.270 pp. 208-215
acetone, bioethanol, biomass, corn stover, distillation, enzymatic treatment, ethanol, ethanol production, fermentation, glucose, hemicellulose, liquefaction, mass transfer, mixing, oxidation, prebiotics, saccharification, slurries, viscosity, xylanases, xylooligosaccharides
Ethanol production at high-gravity promise to achieve concentrations over the threshold for an economical distillation process and concurrently reduce water consumption. However, a persisting limitation is the poor mass transfer conditions resulting in low ethanol yields and concentrations. Hereby, the combination of an acetone/water oxidation pretreatment process (AWO) with a liquefaction/saccharification step, using a free-fall mixer, before simultaneous saccharification and fermentation (SSF) can realize ethanol concentrations of up to ca. 74 g/L at a solids content of 20 wt%. The free-fall mixer achieved a biomass slurry viscosity reduction by 87% after only 2 h of enzymatic saccharification, indicating the efficiency of the mixing system. Furthermore, the direct enzymatic treatment of AWO pretreated corn stover (CS) by a GH11 recombinant xylanase, led to the production of xylooligosaccharides (XOS) with prebiotic potential and the removal of insoluble fibers of hemicellulose improved the glucose release of AWOCS by 22%.