Table 2.
Composition of the steam-pretreated substrates
| Spruce (SPS) | Wheat straw (SPWS) | Bagasse (SPB) | |||||
| g/L whole slurry | % of WIS | g/L whole slurry | % of WIS | g/L whole slurry | % of WIS | ||
| Total DM | 203.2 | - | 113.1 | - | 138.9 | - | |
| WIS | 135.2 | - | 77.1 | - | 98.5 | - | |
| Solid fraction | Glucan | 73.1 | 54.0 | 50.2 | 65.1 | 59.6 | 60.5 |
| Xylan | n.d. | n.d. | 1.6 | 2.1 | 6.6 | 6.7 | |
| Galactan | 0.7 | 0.5 | 0.5 | 0.6 | n.d. | n.d. | |
| Arabinan | n.d. | n.d. | 0.9 | 1.2 | 0.3 | 0.3 | |
| Mannan | 3.1 | 2.3 | n.d. | n.d. | n.d. | n.d. | |
| Insoluble lignin | 57.2 | 42.3 | 20.9 | 27.2 | 26.6 | 27.0 | |
| Liquid fraction | Glucose | 22.4 | - | 2.3 | - | 2.6 | - |
| Glucose oligomers | 1.7 | - | 0.6 | - | 1.3 | - | |
| Xylose | 9.7 | - | 21.8 | - | 10.9 | - | |
| Xylose oligomers | n.d. | - | 3.5 | - | 18.1 | - | |
| Galactose | 4.1 | - | 1.1 | - | 0.8 | - | |
| Galactose | |||||||
| oligomers | n.d. | - | 0.1 | - | 0.7 | - | |
| Arabinose | 2.3 | - | 3.3 | - | 1.5 | - | |
| Arabinose | |||||||
| Oligomers | n.d. | - | n.d. | - | 0.6 | - | |
| Mannose | 20.9 | - | n.d. | - | 0.8 | - | |
| Mannose | |||||||
| oligomers | 0.1 | - | n.d. | - | n.d. | - | |
| Lactic acid* | 2.4 | - | 0.1 | - | 0.5 | - | |
| Glycerol | n.d. | - | n.d. | - | 0.3 | - | |
| Acetic acid | 4.6 | - | 2.1 | - | 3.6 | - | |
| HMF | 2.3 | - | 0.3 | - | 0.1 | - | |
| Furfural | 1.4 | - | 1.0 | - | 1.0 | - | |
| Soluble lignin | 2.3 | - | 2.1 | - | 3.0 | - | |
WIS, water-insoluble solids; DM, dry matter; HMF, hydroxymethylfurfural, n.d., not detected
*The lactic acid component was probably some other organic acid that had the same retention time as lactic acid.
The values presented are the average of two separate measurements, and the standard deviations are <5%.