Interaction of starch and casein

• Modified starches and casein were placed in a simulation yoghurt environment.
• Electrostatic adhesion, steric stabilization and hydrogen bond might co-exist.
• Electrostatic adhesion was the main interaction of phosphate starch and casein.
• Steric stabilization played a main role in the gel with OSAS.

Starch was commonly used to improve the stability of set yogurt. In this research, casein and modified starches were placed in a simulated yoghurt system giving the advantage of a low variation in the environment parameters compared to a natural yoghurt system. The interactions between modified starches (phosphate starch, hydroxypropyl starch and starch ester of octenyl succinic) and casein were investigated with several independed types of measurements methods. The combination of zeta potential and fluorescence micrograph were used to research the interactions between modified starches and casein. And the results proved that modified starches not only absorbed with casein via electrostatic forces, but also had steric stabilization. Besides this, fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to investigate the role of hydrogen bonds between modified starches and casein. It could be deduced that the interactions of modified starches and casein included electrostatic adhesion, steric stabilization and hydrogen bond. At the same time, electrostatic adhesion was the main interaction between phosphate starch and casein. The main role of the interactions between starch ester of octenyl succinic and casein should be steric stabilization.

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