Structure and rheological properties of carrageenans extracted from different red algae species cultivated in Cam Ranh Bay, Vietnam

摘要

-Carrageenan was extracted from three subspecies of Kappaphycus alvareziiK. alvarezii, K. striatum, and K. malesianusand -carrageenan was extracted from Eucheuma denticulatum. Mild water extraction was used in order to obtain carrageenan in the native form. The yield was higher for the raw extract from K. alvarezii (42%) than for the other species (32-37%). NMR showed that the samples contained only small amounts of other carrageenan types. The structural and rheological properties were characterized after extensively dialysis against NaCl and pure water. The molar mass and the radius of gyration determined by light scattering were found to be close for all samples. The viscosity was determined as a function of the shear rate at different concentrations. The zero shear viscosity of -carrageenan extracted from K. alvarezii was found to be systematically larger than the other carrageenan samples. Gelation induced by adding KCl was found to occur at approximately the same gelation temperature leading to gels with approximately the same stiffness.