## 3 Results and Discussion
### Gastrointestinal Stability of Phenolic Compounds from Purslane  
According to the available data, there is no previous study on the gastrointestinal stability of the dominant phenolic compounds from purslane extract using an in vitro digestion method. In this study, a static INFOGEST in vitro digestion method mimicking gastric and small intestinal phases of digestion is used. This method is now recognized as a standardized and practical static digestion method developed within the COST INFOGEST network. It uses constant ratios of meal to digestive fluids and a constant pH value for each step of the simulated digestion [31]. Figure 4 shows the results of total phenols in unground freeze-dried purslane and purslane powder before and after simulated gastric and intestinal digestion. The results show that the highest content of total phenolics before and after in vitro simulated digestion was determined in the PPB sample (655.82 mgGAE/L and 475.26 mgGAE/L), while the lowest content of total phenolics was determined in the PPP sample (395.43 mg GAE/L and 316.56 mg GAE/L). The extracts of PPK and PPB had higher total phenolics than the unground sample (control) (average 140%). The gastrointestinal stability of total phenols was higher in all samples after the gastric phase than after the intestinal digestion phase. In general, the stability of phenolic compounds decreased by 20% after the intestinal digestion phase. The reduction in the content of phenolic compounds after the in vitro simulated intestinal digestion phase is observed by many authors and could be related to their low alkaline stability [40; 41; 42]. The range of total phenols in purslane powder extracts is in agreement with other authors [43; 44]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{3}{c}{**Color Parameters**} & & & \\ \multicolumn{1}{c}{} & \multicolumn{1}{c}{\(L^{*}\)} & \(a^{*}\) & \(b^{*}\) & \multicolumn{1}{c}{**Chroma**} & \multicolumn{1}{c}{**Hue**} \\ \hline PPK & 53.64 \(\pm\) 0.09 ab & 1.4 \(\pm\) 0.01 b & 25.87 \(\pm\) 0.04 a & 25.91 \(\pm\) 0.04 a & 86.9 \(\pm\) 0.03 b \\ PPB & 61.68 \(\pm\) 2.22 a & 1.32 \(\pm\) 0.13 b & 26.73 \(\pm\) 0.77 a & 26.76 \(\pm\) 0.78 a & 87.18 \(\pm\) 0.19 a \\ PPP & 39.50 \(\pm\) 17.34 b & 1.67 \(\pm\) 0.02 a & 22.77 \(\pm\) 0.03 b & 22.83 \(\pm\) 0.03 b & 85.80 \(\pm\) 0.05 c \\ \hline \hline \end{tabular} Values represent the means \(\pm\) standard deviations of three biological replicates and three technical replicates. Different letters indicate significant differences among the samples in a column (one-way ANOVA, Duncan test, \(p\leq 0.05\)). PPK = purslane powder after grinding with a knife mill; PPB = purslane powder after grinding with a ball mill; PPP = purslane powder after grinding with a planetary ball mill  
\end{table} 
Table 1: Color parameters of obtained purslane powders. Table 2 shows the gastrointestinal stability of the dominant phenolic compounds from unground freeze-dried purslane and purslane powders obtained via different grinding techniques. The dominant phenolic compounds identified in the extracts of unground purslane and purslane powders were phenolic acids, mainly protocatechuic, chlorogenic, and ferulic acids. PPK and PBB showed a higher content of chlorogenic acid than the unground sample (control), while all extracts from purslane powders had a higher content of ferulic acid compared to the unground sample. Compared to the other powders, the ferulic acid content in the undigested extract of purslane powder obtained with a ball planetary mill was more than 2 times higher than in the other samples (Table 2). This shows that the grinding technique can alter the phenolic profile of plant powders. There are not many studies on the effects of different grinding techniques on phenolic composition. However, [PERSON] et al. [45] showed that the grinding method can affect the phenolic composition and antioxidant capacity of Tartary buckwheat flour.