Fig. 2

Stage 1 glucan (G) and xylan (X) material balances based on 100 g of glucan plus xylan in each raw Populus variant for liquid (L) and solid (S) streams produced by hydrothermal pretreatment of Populus natural variants at 200 °C for 22.7 min. The sugar degradation products measured in the pretreatment liquor included levulinic acid, formic acid, 5-HMF, and furfural and were adjusted to the corresponding amount of glucan or xylan based on the appropriate stoichiometry. Note: Formic acid has the potential to form from either glucose or xylose; however, it was assumed to form from xylose since xylan/xyloglucan degradation was predominant while glucan degradation was minimal