The objective of this paper was to present the effect of concentration level of various cations, pH, and sucrose concentration level on the rheological properties of solutions and gels of some selected fractions of carrageenan. The rheological properties of various fractions of carrageenan were determined by measuring the viscosity and texture of the solutions and gels produced. The highest viscosity (450 mPa·s) showed the polysaccharide solution in 0,15 M CaCl2. In the case of the two gelling fractions of carrageenan, the increase in the concentration level of all the salts used caused the increase in the gelation temperature. The range of the gelation temperature of ι-carrageenan was much higher than this of the κ-carrageenan fraction, and it was from 48°C to 73°C. However, the increase in pH impacted the increase in both the gelation temperature of κ-carrageenan and in the hardness of its gels. The increase in pH from 3 to 8 caused that the gelation temperature rose from 21°C to 26°C. When sucrose was added, the hardness of κ-carrageenan gels rose, however, the gels having high sugar concentration levels (30%) were very fragile.
iota carrageenan, kappa carrageenan, rheological properties