and Wyman, 2008). As an alternative, hot water pretreatment
induces similar chemical reactions as dilute acid pretreatment
because of the increased hydronium ion concentration at high temperatures
and pressures, but is more environmentally friendly and
entails lower operation and capital costs (Mosier, 2013). A large
fraction of hemicellulose is hydrolyzed to liquid soluble oligosaccharides,
while a small fraction is hydrolyzed to monomeric sugars,
preventing the formation of furan inhibitors (Mosier et al., 2005).
However, aqueous pretreatment requires 20–50 C higher temperatures
and 5–15 min longer processing times than dilute acid pretreatment
for optimal performance (Mosier, 2013).