RHEOLOGY OF SODIUM CASEINATE-CARRAGEENAN MIXTURES

The main effects and interactions of mixtures of sodium caseinate, kap pa- or l-carrageenan, sodium chloride, calcium chloride and hydrogen i ons on the rheological properties in aqueous systems cooled to 5C were quantified. Response surface methodology was used to display the resu lts for five different response variables: gelation temperature, consi stency index (kappa), dynamic power law factor (n*), critical strain (gamma(c)), and syneresis. The gelation profiles observed for both kap pa- and l-carrageenan systems demonstrated that the sol-gel transition in sodium caseinate-carrageenan mixtures was due to electrostatic int eractions of free carrageenan loops or tails with the intewention of c ations. Caseinate molecules did not play a major role in this process. The electrostatic nature of the interactions was further demonstrated by the significant influence of salts and pH on the consistency and b rittleness of the gels (represented by kappa and gamma(c), respective ly). Consistency and brittleness were inversely related as well as con sistency and syneresis. Syneresis was negligible in L-carrageenan gels and was reduced by sodium caseinate and sodium chloride in the kappa- carrageenan systems.