## 3 Results and Discussion
### Evaluation of Physical-Chemical and Functional Stability  
'Aglianico' leaves extract is an important resource of polyphenols, responsible for numerous beneficial effects. However, they are very susceptible to high temperatures humidity, oxygen, and light [10]. Dried herbal extracts, as well as materials in an amorphous state, generally show high instability to storage with uncontrolled temperature and humidity, can lose their stiffness and flow, and their permeability to gasses increases dramatically leading to increased spoilage in the final products. Amorphous materials can collapse, and their storage life is shortened as degradation or oxidation reactions can increase. To  
Figure 6: In-vitro dissolution profile in water of the raw extract (AGL-28 dark green line) and MPA powder (light green line). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Bulk Density (g/cm3) \(\pm\) S.D.*** & **Tap Density (g/cm3) \(\pm\) S.D.** & **HR \(\pm\) S.D.** & **CI \(\pm\) S.D.** & **Flow Character** \\ \hline MPA & 245.70 \(\pm\) 7.16 & 269.99 \(\pm\) 9.19 & 1.10 \(\pm\) 0.01 & 9.00 \(\pm\) 0.01 & Excellent \\ \hline \hline \end{tabular}  
* Standard deviation; the results are expressed as an average of triplicate analyses. Data are mean \(\pm\) S.D.  
\end{table} 
Table 8: Flow properties of MPA powder. understand whether the encapsulation process might have improved the stability of the extract, the spray-dried powders were stressed under harsh storage conditions and results were compared to the extract raw. The changes in the materials were detected by analyzing their solid-state, as well as the polyphenol stability, which was evaluated verifying their content and the antioxidant capability. As it is evident from the images in Figure 7a,c, after 6 months of storage, the raw extract is completely physically modified. It is a dark, hard, shapeless, and sticky mass that has lost its original solid-state. Conversely, MPA exhibits no changes in color and solid-state while maintaining a powdery appearance. Macroscopically, some areas of dust compacted into small agglomerates are visible (Figure 7b). SEM analysis confirmed the formation of few particle aggregates which, however, do not affect the microparticle solid-state (Figure 7d). The selection of a hydrocolloid protector as pectins, able to interact in microparticles formation during the spray-drying process, can allow stabilizing the extract within the particles in an amorphous state by providing wall protection. These results have been also confirmed by thermal analysis (DSC). The thermo-analytical curves of the raw extracts before (blue line) and after the storage (black line) (Figure 8) are completely different. After six months, it is visible a new peak at 60 \({}^{\circ}\)C due to the modified physical state. On the contrary, MPA powder, after 6 months of storage does not show new peaks or degradation events confirming the stability of the solid state. As shown by DSC curves (Figure 8, lines red and green) the minimum variation for MPA 6 months storage, is in the thermal trend between 60 and 80 \({}^{\circ}\)C which could be due to the surface humidity adsorbed during the storage phase, and which slightly modify the trend of the curve without giving rise to degradation phenomena or the formation of  
Figure 7: Macroscopic and microscopic images of AGL-28 extract (**a,c**) and MPA powder (**b,d**) after 6 months of harsh storage conditions. crystalline clusters, evidenced by the absence of new peaks or new endothermic events, also confirming the stability of the amorphous state. The MPA spray-dried powder maintains its features also under harsh storage conditions (red line and green line, Figure 8) making it an ideal candidate suitable for manufacturing purposes. Polyphenols are a class of molecules susceptible to high temperatures, oxygen, and light. For this reason, the polyphenol content and the functional activity of AGL-28 were verified after the spray-drying process (MPA) and after six months of storage under accelerated stability conditions.