This was observed for all ionic forms, but it was most evident for the potassium form which would also be the predominant form in commercial carrageenans . Although the sodium and calcium form showed a comparable morphology, the corresponding samples contained clearly larger ice crystals. The ice crystal images obtained for LC2 suggest a comparably high IRI activity for all forms. In addition, a rectangular ice crystal morphology was observed, which was most noticeable for the calcium form. Therefore, this carrageenan has at least a comparable although not identical functionality than κ-carrageenan despite its clearly different molecular composition. The samples IC1 and LC1 showed rather circular ice crystals as well as a rather low IRI activity for all cation forms. Although the ice crystals obtained from the calcium form were smaller, they were still visibly larger than the ones obtained from KC1 and LC2. A comparison of the monocationic carrageenans and the unmodified carrageenans showed that the cation-exchange is suitable to enhance the IRI activity of carrageenans: The ice crystal images indicated smaller ice crystals for the individual most active monocationic forms than for the unmodified carrageenans.