## 3 Results and Discussion
### Simulating Agro-Based Materials Production
#### 3.5.2 Binderless Particle Board Simulation--Hot Water Extraction  
* pH monitoring during hot water extraction  
The pH values measured at 0, 30, and 60 min for each condition in the \"binderless particle board\" simulation are summarized in Table 8. The conditions include milli-Q water at room temperature (RT) and 100 \({}^{\circ}\)C. This aim is to evaluate the effects of temperature on pH changes. In the case of extractions conducted at room temperature, the pH for both types of hemp shiv remained stable at approximately 5.6 (Table 8). However, when the extraction temperature was increased to 100 \({}^{\circ}\)C, the initial pH of 6.21 for HS1 decreased to 5.61, indicating a drop of 0.60. Conversely, for HS2, the pH increased from 6.24 to 6.77, reflecting a rise of about 0.53. Notably, no significant pH change was observed between HS1 at room temperature and HS1 at 100 \({}^{\circ}\)C at 60 min, and both stabilized at a pH of around 5.6. In contrast, a slight increase in pH was observed in HS2 at 100 \({}^{\circ}\)C compared to its room temperature control condition after the same period. The pH decrease in HS1 at 100 \({}^{\circ}\)C between 0 and 60 min could be attributed to the release of highly methyl-esterified pectins, which are composed of uronic acids such as galacturonic acid and glucuronic acid. These compounds can be extracted with boiling water, as noted in previous studies [58; 59; 60]. Additionally, the drop in pH might also be due to the release of phenolic acids, including chlorogenic acid, vanillic acid, caffe acid, p-coumaric acid, ferulic acid, and gallic acid, all of which are known to be present in \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Time (min)** & **0** & **30** & **60** & \(\Delta_{\text{9-60}}\) \\ \hline HS1 RT & 5.60 & 5.66 \(\pm\) 0.02 & 5.65 \(\pm\) 0.02 & 0.05 \\ \hline HS2 RT & 5.66 & 5.63 \(\pm\) 0.02 & 5.64 \(\pm\) 0.02 & 0.02 \\ \hline HS1 100 \({}^{\circ}\)C & 6.21 & 5.75 \(\pm\) 0.05 & 5.61 \(\pm\) 0.08 & 0.60 \\ \hline HS2 100 \({}^{\circ}\)C & 6.24 & 6.53 \(\pm\) 0.12 & 6.77 \(\pm\) 0.15 & 0.53 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: pH monitoring at 0, 30 and 60 min of extraction simulating process for “binderless particle board” simulation in HS1 and HS2. hemp [61; 62; 63; 64]. On the other hand, the slight pH increase observed in all replicates of HS2 at elevated temperatures is a phenomenon that remains unclear. It suggests that HS2 may release fewer uronic or phenolic acids compared to HS1, which would otherwise contribute to a pH decrease. Instead, HS2 might be releasing more neutral compounds, such as water-soluble tannins, flavonoids, or neutral ones like D-glucose, D-xylose, and D-galactose, which could account for the observed pH rise. * Hemp shiv mass losses are presented in Figure 7.  
The mass losses at room temperature (RT) are 9.7% for HS1 and 2.1% for HS2. When the temperature is increased to 100 \({}^{\circ}\)C, the mass losses rise to 12.0% for HS1 and 3.3% for HS2. As consistently observed, HS1 releases more compounds than HS2. These released compounds could be part of the soluble fraction, which is more readily extracted by polar solvents such as water. At 100 \({}^{\circ}\)C, these compounds could include methyl-esterified pectins [59; 60] and polyphenols such as chlorogenic acid, vanillic acid, or caffe acid [62]. The increased mass loss suggests that more surface area is exposed as these compounds are released. To better understand the effects of these extractions on the material's physical properties, we can examine the specific surface area of the hemp shiv by utilizing Dynamic Vapor Sorption (DVS) analysis and the Brunauer-Emmett-Teller (BET) model. * Specific surface area (\(a_{s}\))  
The specific surface area data are presented in Table 9. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Control** & **RT** & **100 \({}^{\circ}\)C** \\ \hline HS1 & 157.9 & 164.3 & 166.3 \\ \hline HS2 & 153.2 & 171.7 & 139.3 \\ \hline \hline \end{tabular}
\end{table}