Glycerol-assisted one-step instant catapult steam explosion enhances enzymatic digestibility of corn stover

Abstract

Glycerol-assisted one-step instant catapult steam explosion (ICSE) was studied for corn stover pretreatment. Glycerol addition reduced lignin content from ∼32 % to ∼24 % in pretreated solid residues with a stover/glycerol ratio from 1:0.0 to 1:2.0. Glycerol addition might help to reduce the formation of pseudo-lignin with the reduction of the total lignin recovered in pretreated solid residue from 114 % (possibly because of pseudo-lignin contribution) to 81 %. Furthermore, atomic forced microscopy analysis showed that glycerol addition improved surface roughness of pretreated corn stover. Moreover, it was proposed that glycerol-assisted ICSE likely led to the reactions of glycerol with lignin and lignin-derivatives through α-etherification and γ-esterification, preserving lignin internal β-O-4 linkages and preventing lignin condensation. Finally, enzymatic hydrolysis of corn stover pretreated by glycerol-assisted ICSE at a stover/glycerol ratio of 1:1 led to a glucan digestibility in solid residues of 98.4 % and a glucose yield of 79.3 %, which were 27.9 % and 44.7 % higher than those without glycerol addition, respectively.