Gel–sol–gel transition of kappa-carrageenan and methylcellulose binary systems studied by differential scanning calorimetry

• A phase diagram of kappa-carrageenan/methylcellulose binary systems was established.
• Transition temperatures measured by DSC and visual observation.
• Three regimes were observed.
• Gel–sol–gel sinusoidal transition was observed in intermediate regime.

Kappa-carrageenan (κC) was mixed with methylcellulose (MC) with various mixing ratios. Phase transition behaviour of the above mixed solutions with 1 and 2% concentration was investigated by visual observation and differential scanning calorimetry (DSC). Three regimes showing unique transition behaviour were observed: Regime I which is an MC rich region where only sol–gel transition is found, Regime II an intermediate mixing range of κC and MC where sinusoidal change of gel–sol–gel transition was observed, and Regime III a κC rich region where only gel–sol transition was detected. A phase diagram of κC/MC binary systems was established based on transition temperatures obtained by visual observation and DSC.