# Single-Stage Fractionation of Vine Shoots Using Microwave Heating
## 3 Results and Discussion
### Enzymatic Hydrolysis of the Processed Solid from Fractionation Treatment  
Biorefineries require the integral conversion of the feedstocks into a scope of biofuels, chemicals, and materials. For this purpose, the cellulose-enriched solids (denoted PSO) obtained under optimal fractionation conditions for OS manufacture were employed as substrates for enzymatic hydrolysis. Figure 7 shows the compositional data obtained for PSO. Cellulose was the major component (49.3%), together with 6.4% xylan, which was not completely removed upon fractionation (%Hr = 74.5%). Considering all the hemicellulose components, this fraction accounted for 10% of PSO. Table 2 lists the concentrations of xylose and glucose (and the respective conversions of xylan and cellulose) obtained in PSO hydrolysis performed at diverse reaction times and enzyme charges. The concentrations of glucose and xylose are expressed in g/L, whereas the conversions of cellulose and xylan into glucose and xylose were calculated based on their respective potential concentrations. The highest glucose concentration (34.9 g/L, corresponding to 92.5% cellulose conversion) was reached, operating at ESR = 20 for 98 h, although 29.3 g glucose/L (cellulose conversion, 77.5%) was achieved after 48 h. A comparison of data obtained in assays at ESR 10, 15 and 20 showed that lower glucose concentrations were obtained at ESR = 10, including if 83.1% of conversion was reached in this condition and at the longest enzymatic hydrolysis time considered. The enzymatic complex caused not only the hydrolysis of cellulose, but also the conversion of xylan into xylose, owing to the xylanolytic activity of the Cellic CTet2 concentrate, a fact documented in literature [30; 42]. Xylose concentrations in the range 4.2-4.3 g/L, corresponding to xylan conversions into xylose above 90%, were reached in all the experiments after 96 h. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Glucose Concentration (g/L)**} & \multicolumn{3}{c}{**Conversion of Cellulose into Glucose (\%)**} \\ \hline
**Time (h)** & **ESR = 10** & **ESR = 15** & **ESR = 20** & **ESR = 10** & **ESR = 15** & **ESR = 20** \\ \hline
**0** & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 \\
**24** & 16.7 \(\pm\) 1.1 & 18.9 \(\pm\) 0.2 & 22.8 \(\pm\) 0.6 & 44.3 \(\pm\) 2.0 & 49.9 \(\pm\) 0.5 & 60.4 \(\pm\) 1.2 \\
**48** & 22.8 \(\pm\) 0.4 & 27.2 \(\pm\) 0.1 & 29.3 \(\pm\) 0.4 & 60.3 \(\pm\) 0.8 & 71.9 \(\pm\) 0.1 & 77.5 \(\pm\) 0.7 \\
**72** & 28.4 \(\pm\) 0.1 & 31.5 \(\pm\) 0.8 & 32.9 \(\pm\) 0.4 & 75.2 \(\pm\) 0.2 & 83.5 \(\pm\) 1.4 & 87.0 \(\pm\) 0.7 \\
**96** & 31.4 \(\pm\) 0.5 & 31.3 \(\pm\) 0.4 & 34.9 \(\pm\) 0.0 & 83.1 \(\pm\) 0.9 & 82.8 \(\pm\) 0.7 & 92.5 \(\pm\) 0.1 \\ \hline \hline \multicolumn{6}{c}{**Xylose Concentration (g/L)**} & \multicolumn{3}{c}{**Conversion of Xylan into Xylose (\%)**} \\ \hline
**Time (h)** & **ESR = 10** & **ESR = 15** & **ESR = 20** & **ESR = 10** & **ESR = 15** & **ESR = 20** \\ \hline
**0** & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 & 0.0 \(\pm\) 0.0 \\
**24** & 2.4 \(\pm\) 0.1 & 2.6 \(\pm\) 0.2 & 2.6 \(\pm\) 0.1 & 53.1 \(\pm\) 0.6 & 57.5 \(\pm\) 2.3 & 56.5 \(\pm\) 0.8 \\
**48** & 3.0 \(\pm\)0.1 & 3.6 \(\pm\) 0.1 & 3.3 \(\pm\) 0.3 & 66.1 \(\pm\) 1.5 & 77.5 \(\pm\) 1.5 & 71.6 \(\pm\) 4.2 \\
**72** & 3.8 \(\pm\) 0.1 & 4.2 \(\pm\) 0.0 & 4.1 \(\pm\) 0.3 & 82.0 \(\pm\) 1.0 & 90.2 \(\pm\) 0.4 & 89.2 \(\pm\) 5.3 \\
**96** & 4.2 \(\pm\) 0.0 & 4.2 \(\pm\) 0.2 & 4.3 \(\pm\) 0.2 & 91.0 \(\pm\) 0.5 & 91.8 \(\pm\) 2.4 & 93.6 \(\pm\) 2.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results achieved in the enzymatic hydrolysis of solids from the fractionation stage (PSO). The concentrations of glucose and xylose are expressed as g/L \(\pm\) standard deviation. The conversions of cellulose and xylan into glucose and xylose are expressed as % \(\pm\) standard deviation.