Rheology and structure of mixtures of ι-carrageenan and sodium caseinate

Mixtures of ι-carrageenan (IC) and sodium caseinate (SC) were investigated and the results are compared with a similar study of mixtures of κ-carrageenan (KC) and SC. Segregative phase separation was observed at high biopolymer concentrations and the binodal was determined. At low IC concentrations, SC formed aggregates involving a very small amount of IC that were characterized with light scattering. The influence of adding SC on the gelation of IC during cooling and the shear modulus of the gels was studied in the presence of NaCl or KCl. The main conclusion of this work is that SC binds to both IC and KC, in the coil conformation as well as in the helix conformation, but that its effect on the rheology is much weaker for IC than for KC.