摘要 : The issue addressed here is whether kappa carrageenan (kappa-car) and iota carrageenan (iota-car) mixed in aqueous solution microphase separate during gelation as has been claimed in the literature. Rheological properties and micr... 展开 The issue addressed here is whether kappa carrageenan (kappa-car) and iota carrageenan (iota-car) mixed in aqueous solution microphase separate during gelation as has been claimed in the literature. Rheological properties and microstructure of individual kappa-car and iota-car solutions as well as their mixtures were studied at different concentrations (5, 10, 20 g/L) in the presence of CaCl2(0-100 mM). Mixtures showed a two-step gelation process at gelation temperatures (T-c) that coincided with those of corresponding individual kappa-car and iota-car solutions. However, the stiffness of the mixed gels was much higher than the sum of the corresponding individual gels. Confocal laser scanning microscopy (CLSM) and turbidity measurements showed that the kappa-car gel was always more heterogeneous than the iota-car gel, but less in the mixture than in the individual systems. The results show that microphase separation of iota-car and kappa-car in mixed gels is highly unlikely. It is suggested that the increased stiffness of the mixed gels is caused by co-aggregation of kappa-car and iota-car or a different structure of the kappa-car formed in the mixture. 收起