Effects of iota-carrageenan on the rheological properties of starches

The phycocolloid iota-carrageenan (ι-CAR) was extracted from the Brazilian seaweed Meristiella gelidium. At a concentration of 5 mg ml−1 it was mixed with solutions of common corn starch (CS), high amylose starch (MS), waxy corn starch (WS) and YS starch (YS), to give systems at a final concentration of 25 g l−1, which were subjected to rheological measurements. Each mixture gave rise to a different behaviour under dynamic rheological conditions showing a distinct degree of interaction between ι-CAR and the starch. The presence of ι-CAR in ι-CAR-WS, ι-CAR-MS and ι-CAR-CS systems resulted in synergy manifested as enhancements in thermal stability (absence of hysteresis), resulting in thermoreversible gels softer and more stable between 45 and 85 °C. In the ι-CAR-YS system, the synergistic effect occurred as an improvement in solid character, increasing the elastic nature of the gel, suggesting that the structural characteristic of YS, more regular structure with amylopectin having a low molar mass, can contribute to enhanced intermolecular binding.