TY - JOUR
T1 - Swelling of whey and egg white protein hydrogels with stranded and particulate microstructures
AU - Li, Hui
AU - Zhao, Lei
AU - Chen, Xiao Dong
AU - Mercadé-Prieto, Ruben
N1 - Funding Information:
This work was supported by the project funding from the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions and the “Jiangsu Specially-Appointed Professors Program” of China, and the Youth Fund of Natural Science Foundation of Jiangsu Province of China (No. BK20140343 ). Appendix A
Publisher Copyright:
© 2015 Elsevier B.V..
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Swelling of protein hydrogels in alkaline conditions strongly depends on the gel microstructure. Stranded transparent gels swell as predicted using a modified Flory-Rehner model with the net protein charge. Particulate opaque gels swell very differently, with a sudden increase at a narrow pH range. Its swelling is not controlled by the protein charge, but by the destruction of the non-covalent interactions. Comparable dissolution thresholds, one with pH and another with the degree of swelling, are observed in both types of microstructures. These conclusions are valid for both whey protein isolate (WPI) gels and egg white gels, suggesting that they are universal for all globular proteins that can form such microscructures. Differences are observed, however, from the prevalent chemical crosslinks in each protein system. Non-covalent interactions dominate WPI gels; when such interactions are destroyed at pH ≥ 11.5 the gels swell extensively and eventually dissolve. In egg white gels, the higher degree of disulphide crosslinking allows extensive swelling when non-covalent interactions are destroyed, but dissolution only occurs at pH ≥ 13 when covalent crosslinks are cleaved. The current study highlights that the microstructure of protein hydrogels, a unique particularity of protein systems compared to other synthetic hydrogels, defines swelling.
AB - Swelling of protein hydrogels in alkaline conditions strongly depends on the gel microstructure. Stranded transparent gels swell as predicted using a modified Flory-Rehner model with the net protein charge. Particulate opaque gels swell very differently, with a sudden increase at a narrow pH range. Its swelling is not controlled by the protein charge, but by the destruction of the non-covalent interactions. Comparable dissolution thresholds, one with pH and another with the degree of swelling, are observed in both types of microstructures. These conclusions are valid for both whey protein isolate (WPI) gels and egg white gels, suggesting that they are universal for all globular proteins that can form such microscructures. Differences are observed, however, from the prevalent chemical crosslinks in each protein system. Non-covalent interactions dominate WPI gels; when such interactions are destroyed at pH ≥ 11.5 the gels swell extensively and eventually dissolve. In egg white gels, the higher degree of disulphide crosslinking allows extensive swelling when non-covalent interactions are destroyed, but dissolution only occurs at pH ≥ 13 when covalent crosslinks are cleaved. The current study highlights that the microstructure of protein hydrogels, a unique particularity of protein systems compared to other synthetic hydrogels, defines swelling.
KW - Microstructure
KW - Protein hydrogel
KW - Swelling
UR - http://www.scopus.com/inward/record.url?scp=84949215063&partnerID=8YFLogxK
U2 - 10.1016/j.ijbiomac.2015.11.018
DO - 10.1016/j.ijbiomac.2015.11.018
M3 - Article
C2 - 26627602
AN - SCOPUS:84949215063
SN - 0141-8130
VL - 83
SP - 152
EP - 159
JO - International Journal of Biological Macromolecules
JF - International Journal of Biological Macromolecules
ER -