DIFFERENTIAL SCANNING CALORIMETRIC STUDIES OF PHILIPPINES NATURAL GRADE KAPPA-CARRAGEENAN

Using differential scanning calorimetry, the gel-sol transition temper atures were compared for KCl-precipitated kappa-carrageenan and Philip pines natural grade-(PNG) kappa-carrageenan. The latter contains cellu lose, which is associated with the carrageenan in seaweed. This leads to lower gel-sol transition temperatures. More heat absorption (-Delta H-m=79 kJ/mol) is required for the formation of junction zones for th e PNG kappa-carrageenan than the KCl-precipitated kappa-carrageenan (- Delta H-m=40 kJ/mol). This behaviour can be attributed to the cellulos e interspersing between kappa-carrageenan aggregates in the PNG kappa- carrageenan gels.