**5. Conclusions**

In this study, the structural and functional changes in ASC and PSC were investigated, and it was found that the use of pepsin had contributed to the increase in the collagen yield; however, it produced many smaller protein fragments after extraction. Therefore, the functional and structural properties were investigated in ASC and PSC, and no significant differences were observed in both collagens, which directly revealed that the pepsin treatment did not affect the secondary structures such as α helix, β-sheet, β-turn, and triple helix. Therefore, the physicochemical, structural and functional properties of collagens indicate that the PSC could be an appropriate material for biomaterial fabrication in tissue regeneration applications.

**Author Contributions:** Conceptualization, J.E. and W.W.; validation, J.E.M.S.d.V.; formal analysis, B.G.; investigation, B.G. and C.H.; resources, W.W.; writing—original draft preparation, J.E. and B.G.; writing—review and editing, B.B. and Z.P.; supervision, J.E.; project administration, W.W.; funding acquisition, J.E. and W.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research work was financially supported by the National Natural Science Foundation of China (Grant No. 82173731), the Research Fund for International Young Scientists (Grant No. 81750110548), the Natural Science Foundation of Shanghai (Grant No. 21ZR1427300) and Internal funding from UCAM- Universidad Católica San Antonio de Murcia, (Grant No. PMAFI-27/21), Murcia, Spain.

**Institutional Review Board Statement:** Not applicable. **Data Availability Statement:** Not applicable.

**Acknowledgments:** We are thankful and acknowledge the College of Food Science and Technology, Shanghai Ocean University, China for providing the proper facilities to carry-ou<sup>t</sup> this work.

**Conflicts of Interest:** The authors declare that they have no conflict of interest.
