Untreated | 2.5% Na2SO3 + 1.25% NaOH | 5% Na2SO3 + 2.5 NaOH | 10% Na2SO3 + 5% NaOH | RES-sap | |
---|---|---|---|---|---|
Sample compositiona | |||||
p-Hydroxyphenyl lignin units (H) | 0.6 | 0.4 | 0.4 | 0.1 | 0.6 |
Guaiacyl lignin units (G) | 8.7 | 6.5 | 6.5 | 2.2 | 15.6 |
Syringyl lignin units (S) | 10.1 | 8.1 | 7.5 | 2.3 | 13.4 |
S/G ratios | 1.2 | 1.2 | 1.2 | 1.0 | 0.9 |
Total lignin units | 19.4 | 15.0 | 14.4 | 4.6 | ne |
Total carbohydrate units | 80.6 | 85.0 | 85.6 | 95.1 | ne |
p-Coumarates (pCA) | 10.4 | 10.0 | 9.0 | 1.7 | 2.5c |
Ferulates (FA) | 4.6 | 3.1 | 1.9 | 0.0 | 0.0 |
Main lignin inter-unit linkages and end-groupsb | |||||
β-O-4′ Alkyl-aryl ethers (A) | 60 | 59 | 49 | 42 | 4 |
Phenylcoumarans (B) | 5 | 4 | 4 | 4 | 4 |
Cinnamyl alcohol end-groups (I) | 3 | 3 | 3 | 0 | 2 |