Preparation and characterization of water-soluble chitosan produced by Maillard reaction

The objective of this research was to improve the solubility of chitosan by Maillard reaction with 1% chitosan and 2% reducing sugar (glucose or glucosamine) dissolved in 0.2 M acetic acid, which was adjusted to pH 6.0, and incubated at either 50°C or 70°C for 1–7 days. The physicochemical and rheological properties of the chitosan-saccharide derivatives were also investigated. Results indicated that the solubility of modified chitosan derivatives was significantly greater than that of native chitosan. The solubility of chitosan-glucosamine was higher than that of chitosan-glucose, and the chitosan-glucosamine derivative remained soluble at pH 10. The degree of deacetylation of the derivatives decreased with increasing reaction time. Rheological investigation revealed that the apparent viscosity of the water-soluble chitosan derivatives in aqueous solution depended upon system conditions such as pH, ionic strength, and solution temperature. The measured apparent viscosity decreased as all system conditions increased. As calculated by the Arrhenius equation, the activation energy (Ea) of the derivatives in aqueous solution generally decreased with increasing the extent of Maillard reaction with respect to the reducing sugars used.