## 5 Conclusions  
Since similar studies have not been conducted, our study gives new insights significant for future studies. In this study, the use of HP-\(\beta\)-CD as a carrier and the lyophilization procedure demonstrated to be the best choice in the sample preparation to obtain an aqueous suspension of propolis applicable in the gastrointestinal stability and dialysability analyses of the polyphenolic groups. The obtained propolis-HP-\(\beta\)-CD complex proved to be stable and resistant to the acid-base conditions of GID interaction with enzymes and other ingredients of digestive fluids.  
During all phases of the in vitro GID study, the high contents of the TPs, TFFs, and TFDs of the encapsulated propolis samples with HP-\(\beta\)-CD were established. The results indicated a good bioaccessibility of the main polyphenols group using a propolis-HP-\(\beta\)-CD complex. Furthermore, the centrifugation model showed to more suitable for determining the bioaccessibility of the main polyphenolic groups at the small intestinal level.  
In conclusion, further research should consider the samples from various continental regions and additional data of propolis sampling, like collection season and dominant vegetation in the area of bee activity. Moreover, the chemical composition of the polyphenols in propolis, the amount of cyclodextrin, and the ratio of propolis/cyclodextrin in the inclusion complex should also be investigated.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13169357/s1](https://www.mdpi.com/article/10.3390/app13169357/s1)]([https://www.mdpi.com/article/10.3390/app13169357/s1](https://www.mdpi.com/article/10.3390/app13169357/s1)), Table S1: Preparation of simulated solutions: simulated saliva fluid (SSF), simulated gastric fluid (SGF) and simulated intestinal fluid (SIF), Figure S1: Calibration curve for the content of (A) total phenols (TP) by Folin-Ciocalteu method, (B) total flavones and flavonoids (TFF) by aluminium complexation method, (C) total flavanones/dihydroanvonols (TFD) by 2,4-dinitrophenylhydrazine method.  
Conceptualization, E.P.J., K.S., S.T., I.Z. and A.V.; methodology, E.P.J. and K.S.; validation, E.P.J. and K.S.; formal analysis, E.P.J. and K.S.; investigation, E.P.J., K.S., S.S., D.F., M.P. and A.V.; data curation, E.P.J.; writing-original draft preparation, E.P.J., K.S., I.Z. and M.A.; writing--review and editing, K.S., M.A., I.Z., A.V. and M.B.; visualization, E.P.J., K.S., S.S., D.F. and M.P.; supervision, S.T. and M.B.; statistical analysis, M.B. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was summarized under a Ph.D. thesis (urm:nbn:hr:217:728078) supported by the Croatian Veterinary Institute, Zagreb, Croatia, and did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** The authors extend their appreciation to the Croatian Veterinary Institute, Zagreb, Croatia.  
**Conflicts of Interest:** The authors declare no conflict of interest.