Table 2 showed the results of furfural and HMF
concentrations analyzed by HPLC, in order to confirm
that washing step before saccharification in both NaOH
and H2SO4 pretreated solid residue can reduce
inhibitors comparing to unwashing pretreated biomass.
The results showed that furfural and HMF obtained
after saccharification of washing solid residue from
H2SO4 pretreatment were 0.380 mg/L and 0.402 mg/L,
respectively. There were less than furfural and HMF
from unwashing solid residue (26.476 mg/L and 5.921
mg/L, respectively). In the case of NaOH pretreatment,
no detectable quantity (0.000 mg/L) of furfural and
HMF was present in the hydrolysate of washing solid
residue before saccharification while only 1.215 mg/L
of furfural and undetectable quantity of HMF was