Analysis of structural heterogeneity of κ/β-carrageenan oligosaccharides from Tichocarpus crinitus by negative-ion ESI and tandem MALDI mass spectrometry

► κ/β-carrageenan of the red seaweed Tichocarpus crinitus was investigated. ► Carrageenan was depolymerized with κ-carrageenase to oligosaccharides (DP up to 20). ► MALDI-TOF/TOFMS and ESIMS revealed hybrid κ/β-structure of oligosaccharides. ► The oligosaccharides were able to induce of TNF-α and IL-6 secretion of immune cells.