## 3 Results
### Bioaccessibility of Polypphenols  
The in vitro bioaccessibility and potential absorption of polyphenols after the simulated in vitro GID of a standard mixture of selected polyphenols and ethanolic extracts of Vlp and Zg propolis are shown in Figure 2. Total phenolics, calculated according to Equation (1), were above 100% in the IF-C fraction for all three complexes (Figure 2A). In the Din fraction, the highest values of bioaccessible polyphenols were in the std mix. The differences between bioaccessible contents in IF-C and Din were statistically significant (\(p<0.05\)) for all analyzed complexes. Total phenolics in GID fractions presented in Table 2 showed that TPs are stable during GID. The increases in content after IF-C compared to the US indicated high bioaccessibility, i.e., polyphenols were effectively released from the matrix. In the Din fraction, the content of dialyzable TPs was found to be 54% in the Zg complex and 100% in the std mix. The content of bioaccessible TFFs in all three complexes was high, ranging from 65% to 90% when IF-C model was performed. In the dialysis model, significantly lower values of bioaccessible TFFs were obtained in the Zg complex (\(p<0.05\)) when compared to IF-C. Contemporaneously, the TFFs in Vlp and std mix samples showed better recoveries. The dialyzable fraction Din in the std mix showed very low TEDs, but in the complexes, the situation was different. TFDs in IF-C and Din were very similar, without significant differences (\(p>0.05\)) between them for both Vlp and Zg complexes. Although TFDs in the Din fraction were high, the Dout fraction also contained a large content of bioaccessible compounds. This indicates that most of the TFDs in this study remained outside the dialysis membrane and did not pass through the membrane. The increase in bioaccessible TPs, TFFs, and TFDs during GF and IF-C, compared to the US, indicated the successful release of polyphenols passing through the gastrointestinal tract. \begin{table}
\begin{tabular}{l l c c} \hline \hline \multirow{2}{*}{**Phase**} & \multicolumn{3}{c}{**Total Flavonones/Dihydroflavonols * in Complex**} \\ \cline{2-4}  & **Std Mix** & **Vlp Propolis** & **Zg Propolis** \\ \hline US & 427.0 \(\pm\) 4.8 \({}^{\text{a}}\) & 479.8 \(\pm\) 8.8 \({}^{\text{ab}}\) & 480.6 \(\pm\) 1.5 \({}^{\text{b}}\) \\ OF & 1060.2 \(\pm\) 11.0 \({}^{\text{a}}\) & 643.1 \(\pm\) 21.3 \({}^{\text{b}}\) & 685.2 \(\pm\) 14.0 \({}^{\text{ab}}\) \\ GF & 2245.5 \(\pm\) 53.0 \({}^{\text{a}}\) & 1899.7 \(\pm\) 34.0 \({}^{\text{ab}}\) & 1318.1 \(\pm\) 95.5 \({}^{\text{b}}\) \\ IF & & & \\ IF-C & 2360.2 \(\pm\) 32.3 \({}^{\text{a}}\) & 4609.2 \(\pm\) 40.9 \({}^{\text{b}}\) & 3101.8 \(\pm\) 82.6 \({}^{\text{ab}}\) \\ Din & 17.2 \(\pm\) 34.1 \({}^{\text{a}}\) & 3412.7 \(\pm\) 83.4 \({}^{\text{b}}\) & 3035.1 \(\pm\) 68.2 \({}^{\text{ab}}\) \\ Dout & 3083.3 \(\pm\) 75.6 \({}^{\text{a}}\) & 1507.9 \(\pm\) 27.8 \({}^{\text{b}}\) & 2704.45 \(\pm\) 48.6 \({}^{\text{ab}}\) \\ \hline \end{tabular} US—undigested sample; OF—oral fraction; GF—gastric fraction; IF–C—intestinal fraction after centrifugation; Din—dialyzable fraction; Dout—non-dialyzable fraction; std mix—mixture of standards; Vlp—Valpovo; Zg—Zagreb. * The result expressed as the mean value of \(\mu\)g PC/mL complex \(\pm\) standard deviation (SD); \(n=3\). Statistical significance was tested using the Kruskal Walls non-parametric test and [PERSON]’s post hoc test of mutual phase, with \(p<0.05\). \({}^{\text{a,b}}\)—different letters indicate statistically significant differences (\(p<0.05\)) between complexes std mix, Vlp propolis and Zg propolis in the same digestion phase.  
\end{table}