This can be seen from the detection of ι-carrageenan oligosaccharides by HPLC-MS and the detection of high portions of low molecular weight compounds by HPSEC-RI after ιcarrageenase hydrolysis. However, the HPSEC-RI chromatograms revealed that IC3 is not completely digested and small portions of polymeric compounds with varying molecular weight are present. κ-carrageenase also released significant amounts of κ-carrageenan-derived oligosaccharides and low molecular weight compounds. Furthermore, the κ-carrageenase digestion resulted in a slight shift of the IC3 peak to higher retention times in the HPSEC-RI chromatogram. The underlying, relatively minor reduction in molecular weight suggested that consecutive κ-units are present in rather small blocks. The broad molecular weight distribution after ι-carrageenase hydrolysis could be caused by some long κ-chains, small alternating blocks of κ-and ι-units or some longer carrageenan chains with alternating κ-and ι-units. Nevertheless, the combination of the results indicated that IC3 is largely composed of a ι/κ hybrid carrageenan which mainly contains long blocks of consecutive ι-units and comparably small blocks of consecutive κ-units.