Non-severe thermochemical hydrolysis of stover from white corn and sequential enzymatic saccharification and fermentation to ethanol

• Non-severe thermochemical hydrolysis of stover from white corn.
• Low amounts of furans were released at optimal conditions for xylose release.
• Slurries with 77 g/L of monosaccharides were obtained after saccharification.
• Slurries without detoxification were fermented with ethanologenic bacteria.
• Up to 24 g/L of ethanol was obtained from 15% solid loads.

A parametric study, with an initial load of 15% w/w of dry stover from white corn, was conducted to evaluate the sequential thermochemical hydrolysis (TH), enzymatic saccharification (ES) and fermentation of the whole slurry with ethanologenic Escherichia coli. The TH was designed to release the maximum amount of xylose with a concomitant formation of minimal amounts of furans. It was found that 29.0% or 93.2% of the xylan was recovered as free xylose at 130 °C after 8 min in the presence of 1% or 2% w/w H2SO4 and produced only 0.06 or 0.44 g/L of total furans, respectively. After 24 h of ES, 76.14–77.18 g/L of monosaccharides (pentoses and hexoses) were obtained. These slurries, which contained 0.03–0.26 g/L of total furans and 5.14–5.91 g/L of acetate, were fermented with 3.7 g/L of ethanologenic E. coli to produce 24.5–23.5 g/L of ethanol.