## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline  & & & \multicolumn{8}{c}{**Pretreatment Hydrolyates (\% on Initial Biomass Weight)**} \\ \hline \hline  & & \multicolumn{8}{c}{**Carbohydates Yield (\%)**} & \multicolumn{8}{c}{**Hypoducts Yield (\%)**} & \multicolumn{8}{c}{**SIX\({}^{b}\)**} & \multicolumn{8}{c}{**Total**} & **SX\({}^{b}\)** \\
**Pretext (\({}^{\text{C}}\))** & **Projectate** & **Initial** & **Final pH** & **Glucose** & **XMG** & **Furtural** & **HMF** & **Actic Acid** & **Formic Acid** & **(\%)** & **Removal (\%)** & **Total (\%)** \\ \hline  & 0,0,0x & 6.91 & 3.09 & 0.4 & 11.2 & 0.007 & 0.006 & 1.5 & 0.5 & 5.3 & 18.9 & 77.4 (25.5) & 98.5 \\  & 0,1 ac & 1.60 & 1.41 & 3.5 & 11.5 & 0.024 & 0.008 & 5.1 & 1.0 & 10.6 & 31.7 & 64.7 (23.1) & 96.4 \\  & 0,25x & 1.29 & 1.33 & 2.7 & 14.5 & 0.010 & 0.009 & 4.8 & 1.2 & 7.5 & 30.5 & 67.3 (39.7) & 97.8 \\  & 2,1 ac & 1.57 & 1.69 & 2.4 & 14.5 & 0.030 & 0.014 & 4.8 & 1.3 & 22.4 & 45.4 & 51.2 (20.6) & 97.1 \\
170 & 2,25x & 1.58 & 1.33 & 4.1 & 16.7 & 0.031 & 0.014 & 3.9 & 1.2 & 17.4 & 43.3 & 54.7 (26.6) & 98.0 \\  & 5,1 ac & 2.33 & 1.95 & 2.2 & 17.1 & 0.145 & 0.011 & 4.4 & 0.8 & 21.5 & 46.2 & 52.1 (23.4) & 98.3 \\  & 55,2x & 1.75 & 1.24 & 5.4 & 16.9 & 0.042 & 0.017 & 4.2 & 1.4 & 20.2 & 48.2 & 50.1 (27.3) & 98.2 \\  & 15,0 ac & 4.26 & 2.71 & 2.8 & 17.1 & 0.092 & 0.053 & 3.4 & 1.0 & 21.3 & 45.7 & 55.6 (68.7) & 99.3 \\  & 15,5 ac & 1.44 & 1.32 & 2.6 & 16.9 & 0.362 & 0.056 & 4.6 & 1.5 & 21.6 & 47.6 & 49.5 (26.4) & 97.1 \\ \hline  & 0,0x,0x & 6.85 & 3.02 & 2.4 & 7.00 & 0.028 & 0.014 & 5.7 & 2.7 & 7.3 & 25.1 & 71.8 (25.3) & 96.9 \\  & 0,1 ac & 1.65 & 1.83 & 4.8 & 12.7 & 0.035 & 0.017 & 4.5 & 1.7 & 145 & 38.3 & 60.4 (38.6) & 98.7 \\
190 & 2x,1 ac & 1.85 & 1.63 & 6.0 & 18.5 & 0.031 & 0.017 & 6.5 & 1.6 & 17.1 & 49.7 & 49.6 (20.7) & 99.3 \\  & 158,0 ac & 4.33 & 2.41 & 4.9 & 19.4 & 0.174 & 0.096 & 6.8 & 1.4 & 22.9 & 50.7 & 42.4 (73.0) & 98.1 \\  & 155,5 ac & 1.84 & 1.34 & 6.5 & 19.2 & 0.199 & 0.104 & 7.2 & 1.7 & 21.3 & 56.2 & 39.8 (27.0) & 96.0 \\ \hline \hline \end{tabular}  
* \({}^{\text{A}}\) Sc: bisulfite charge = 5%,25 ac = sulfuric acid charge = 2.5%,\({}^{\text{B}}\) includes all the components that absorbed at 205 nm; (XMG: combined xylose, mannose, and galactose; SUX: soluble lignin yield; SRY: solid residue yield).  
\end{table} 
Table 1: Solid residue yields and dissolved components in the pretreatment hydrolysates, for the different pretreatment conditions of pin wood chips (time at maximum temperature: 30 min). Figure 1 shows the effect of the enzymatic hydrolysis reaction time on the total carbohydrate (includes glucose and XMG) release of the solid residues that were subjected to different pretreatment liquor compositions, at 170 \({}^{\circ}\)C.  
The carbohydrates released by the enzymatic cocktail clearly increases with the increase of acid charge in the pretreatment stage: the total carbohydrate yield increased from 25.2 to 35.4 and 41% when the charge of acid increased from 0 to 1 and 2.5%, with no bisulfite added. Similar behavior was observed for the sodium bisulfite charges of 2 and 5% and the maximum carbohydrates yield was attained at 15s_5 ac (96.9%). However, at low bisulfite charge (2%) it was not possible to attain an acceptable carbohydrate yield in the enzymatic process (51.7 and 57.1% for 2s_1 ac and 2s_2.5 ac, respectively); the S content estimated by SEM-EDX is close 0 and 0.14%, respectively. A drastic increase in enzymatic hydrolysis was observed when the bisulfite charge increased from 2% to 5%, regardless of solid residues yields being of the same order of magnitude (51.7 and 54.7% for 2s_1 ac and 2s_2.5 ac vs. 52.1 and 50.1% for 5s_1 ac and 5s_2.5 ac, respectively). The S content of the 5s_2.5 ac sample determined by SEM-EDX was 0.36%, proving the higher sulfonation of the residual lignin in the solid residue. Figure 2 presents the enzymatic yield as a function of the global porosity (increase) of the solid residue, because of the mass removal.