Effects of Cooling Rate and Sodium Chloride on Polysaccharide Gelation

Abstract

The effects of cooling rate and 0.1∼0.5% sodium chloride (NaCl) on the gelation of 0.8% agar, gellan gum and κ-carrageenan solutions were investigated based on the storage modulus and by differential scanning calorimetry (DSC). Each polysaccharide solution without NaCl had higher values of equilibrium storage modulus at a slow cooling rate than at a rapid cooling rate. However, the enthalpy calculated from the area surrounded by a DSC curve and the base line was not influenced by the cooling rate. The gelation temperature of each polysaccharide solution was elevated and the effect of NaCl addition on the storage modulus of gellan gum and κ-carrageenan was intensified by slowing the cooling rate. Each aggregated molecule core might grow independently at a rapid cooling rate and the formation of network structure of gellan gum and κ-carrageenan at a slow cooling rate might be affected by intermolecular repulsion.