From macroscopic phase separation to microscopic interactions: effects of pH, mass ratio, and ionic strength on phase behavior and thermodynamic mechanism of whey protein isolate - fucoidan complexes.

Authors

Liyuan Zheng, Xing Chen, Guanxin Xie, Qianfei Liu, Yuqin Qin, Qiushuo Chang, Tiehua Zhang, Chunyu Xi

Published in

Food chemistry. Volume 525. Issue Pt 3. Pages 150586. Jul 30, 2026. Epub Jul 30, 2026.

Abstract

This study investigated the effects of pH, mass ratio, and ionic strength on the phase behavior and thermodynamic interactions of whey protein isolate (WPI)-fucoidan (FUC) complexes. The mass ratio was identified as the primary factor governing phase behavior, with a stable homogeneous system observed at a 1:1 (w/w) ratio across pH 2-7. This work quantitatively demonstrated the dual role of ionic strength in regulating WPI/FUC complexation: low NaCl promoted complex formation via enhanced electrostatic interactions, whereas high salt induced phase modulation through combined electrostatic screening and excluded volume effects. Thermodynamic analysis revealed a pH-dependent transition in interaction mechanisms. At pH 4.0 and 5.5, complexation was spontaneous and enthalpy-driven, dominated by electrostatic interactions, while at pH 2.5 the driving force shifted to entropy-driven hydrophobic interactions. These findings provide new mechanistic insights into salt- and pH-regulated phase behavior in protein-polysaccharide systems.

PMID:
42543045
Bibliographic data and abstract were imported from PubMed on 03 Aug 2026.

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