Enhanced enzymatic sugar production from corn stover by combination of water extraction and glycerol-assisted instant catapult steam explosion

Bioresources and Bioprocessing

Table 1 Biomass composition and component recovery in solid residues after ICSE pretreatment

Water extraction prior to ICSE	G:W²	Biomass yield (%)	Content in solid residue (%)³			Recovery in solid residue (%)⁴
Water extraction prior to ICSE	G:W²	Biomass yield (%)	Glucan	Xylan	Lignin	Glucan	Xylan	Lignin
No	0:5	58.7	39.8 ± 1.5	12.9 ± 0.1	25.0 ± 1.0	75.1 ± 2.8	43.0 ± 0.3	98.5 ± 3.9
	2:3	62.8	39.9 ± 0.9	12.2 ± 0.2	26.4 ± 0.4	80.6 ± 1.8	43.5 ± 0.7	111.3 ± 1.7
	3:2	61.7	40.6 ± 0.4	12.1 ± 0.1	26.4 ± 0.8	80.5 ± 0.8	42.4 ± 0.4	109.3 ± 3.3
	4:1	61.1	39.9 ± 0.5	10.4 ± 0.2	28.6 ± 0.2	78.5 ± 1.0	36.1 ± 0.7	117.3 ± 0.8
	5:0	61.5	40.6 ± 0.4	12.3 ± 0.1	26.3 ± 1.1	80.3 ± 0.8	43.0 ± 0.3	108.6 ± 4.5
Yes⁵	0:5	54.6	43.4 ± 0.2	14.5 ± 0.1	23.5 ± 0.4	76.3 ± 0.4	45.0 ± 0.3	86.1 ± 1.5
	4:1	52.2	43.6 ± 0.4	12.6 ± 0.8	24.7 ± 0.2	73.2 ± 0.7	37.4 ± 2.4	86.5 ± 0.7
	Untreated	81.24	36.5 ± 0.1	20.6 ± 0.0	20.9 ± 0.6	95.3 ± 0.3	99.7 ± 0.0	114.0 ± 3.3
Corn stover determined by standard NREL procedure⁵		–	31.1 ± 0.3⁷	17.6 ± 0.2⁸	14.9 ± 0.9	–	–	–

1. All the trials were undertaken at solid/liquid mass ratio of 1:1 except for this one (no additional liquid); 2. G:W = glycerol:water (w/w); 3. the contents of arabinan (excluding water-soluble arabinan) were reduced to no more than 1.4% after pretreatment (data not shown); 4. component recovery in solid residue (%) = Component content (%) in solid residue × Biomass yield (%)/Component content (%) in untreated corn stover × 100; 5. hot water extraction at 90 °C for 2 h removed 18.8% water extractives (corresponding biomass yield of 81.2%); 6. untreated corn stover contained 18.4% water extractives, 5. 5% ethanol extractives and 6.4% ash (determined after both water and ethanol extraction based on the standard NREL procedure); 7. glucan content included 2.6% glucan equivalent (sucrose, glucose and fructose) from water extractives; 8. xylan content included 1.3% xylan equivalent