Understanding starch gelatinization and rheology modeling of tapioca starch- NaCl/CaCl2 blends: Thermodynamic properties and gelatinization reaction kinetics during pre- and post-ultrasonication.

ABSTRACT

The presence of salt can impact the fluid phase and gelatinization process of starch granules. The variation in viscosity and rheology models including the Herschel-Bulkley, the Casson model, and the power law, were determined by adding salts before and after starch ultrasonication. Non-isothermal kinetics can be utilized for the mathematical modeling of the gelatinization process and the evolution of the reaction. Unlike Na+ ions, Ca+2 ions notably elevate viscosity. The Casson model accurately predicts viscosity data. Results indicate that the addition of Na+ ions decreases yield stress by up to 60.4 %, while Ca+2 ions increase by up to 100.8 %. Adding Na+ ions decreases the required thermal energy by as much as 49.6 %, while the presence of Ca+2 ions can lead to a substantial increase of up to 337.1 % compared to control samples. The positive ∆G indicates a non-spontaneous gelatinization process. The addition of NaCl promotes a spontaneous reaction, while the addition of CaCl2 increases the Gibbs energy. The changes in entropy are minimal, implying minimal changes in starches' disorder structure.