Combined pretreatment using ozonolysis and wet-disk milling to improve enzymatic saccharification of Japanese cedar

► Japanese cedar was subjected to ozonolysis and subsequent wet-disk milling (DM). ► Moisture content affected ozone consumption and delignification. ► Ozone treatment removed mainly lignin, but also a small amount of polysaccharide. ► Ozonolysis enhanced the ability of DM, resulting in increased sugar yield. Ozonolysis and subsequent wet-disk milling (DM) were carried out on Japanese cedar (Cryptomeria japonica) to improve sugar production by enzymatic saccharification. When the moisture content reached more than 40%, ozone consumption decreased, resulting in less delignification. Ozone treatment removed mainly lignin, but also small amounts of polysaccharides. The application of DM following the ozone treatment further increased glucose and xylose yields, but had no significant effect on mannose yield, due to the loss of mannan in the ozone-treated product and the lack of mannose-releasing activity in the hemicellulase used. Sugar concentration increased with substrate concentration, when a constant ratio of enzyme to substrate was used.