In the present study, we used well-characterized carrageenans and successfully converted them into their monocationic forms. The samples which contained only potassium, calcium, and, in part, sodium as associated cations were subsequently investigated for their IRI activity in a model system. Our results clearly demonstrated that both the molecular structure as well as the associated cations clearly influence IRI activity. The pure κ-carrageenan KC1 showed the overall highest IRI activity, but only in its potassium form. In contrast, the calcium form of pure ι-carrageenan IC1 was more active than the potassium form. Therefore, a higher IRI activity was observed for cations which lead to a strong helix stabilization for the individual carrageenans . These results suggest that helix formation or a rigid conformation is important for an interaction with the ice crystal surface.