Rate Modeling of Starch Gelatinization under Strong Alkali Conditions

The viscosity and fluidity of a starch solution with a water-starch ratio of 2.0w/w was studied during gelatinisation under strong alkali conditions, in a Co-axial cylinder viscometer for 17g/dm3 - 23g/dm3 concentrations of NaOH solution. The degree of gelatinization was defined in terms of viscosity and the experimental data fit to eleven rate equations based on the mechanism of the unreacted-core model. The model for Product layer diffusion plus Chemical reaction control (F) gave the best fit (0.9930 R2 0.9999) to the experimental data at all sodium hydroxide concentrations studied, with the Product layer diffusion control step dominating at low sodium hydroxide concentrations while the Chemical reaction control step dominated at high sodium hydroxide concentrations. This model can serve as a guide for obtaining specific concentrations of sodium hydroxide to be used for production of an adhesive with a pre-determined viscosity or to develop a robust model for optimising the process of producing adhesives from starch