Thermo-Rheological Memory of κ-Carrageenan Fluid Gels Formed under Flow

Fluid gels are soft materials formed by shearing biopolymer solutions during the sol-gel transition. Their ability to yield and flow beyond a critical stress makes them attractive for designing versatile, biocompatible materials in food, health care and medical applications. Although it is well established that both microstructure and mechanical properties depend on the shear applied during gelation, a unified physical framework linking these features remains lacking. Here, using κ-carrageenan gels as a model system, we use a combination of rheology and confocal microscopy to tackle their shear-induced structuring in fluid gels. We identify a thermo-rheological memory in κ-carrageenan gels formed under flow and show that it arises from a competition between shear and interparticle adhesion, captured by an Adhesion number. The resulting microstructural evolution is reminiscent of the behavior of attractive particulate dispersions under simple shear flow, thereby bridging gels made of macromolecules and particulate gels. This framework provides a route to tune fluid gel properties without altering their composition.