Abstract Using differential scanning calorimetry, the gel-sol transition temperatures were compared for KCl-precipitated κ-carrageenan and Philippines natural grade (PNG) κ-carrageenan. The latter contains cellulose, which is associated with the carrageenan in seaweed. This leads to lower gel-sol transition temperatures. More heat absorption (- ΔH m = 79 kJ/mol) is required for the formation of junction zones for the PNG κ-carrageenan than the KCl-precipitated κ-carrageenan (- ΔH m = 40 kJ/mol). This behaviour can be attributed to the cellulose interspersing between κ-carrageenan aggregates in the PNG κ-carrageenan gels.