Soy protein isolate-chitosan complex condensate: Phase behavior, structure and functional properties

This study investigated the interaction mechanism between soy protein isolate (SPI) and chitosan (CS), and the structure and functional properties of their complex. The results revealed hydrogen bonding and hydrophobic interactions as the main driving forces for formation of soluble SPI/CS complex, while electrostatic interactions as the primary force driving insoluble complex formation. Insoluble complex formation was promoted by an appropriate increase in SPI/CS total concentration (> 0.24 %) and a decrease in NaCl concentration (< 60 mmol/L). After adding CS, SPI decreased in solubility, emulsifying and foaming properties, followed by an increase with pH raised from 3 to 9. CS addition could also change the tertiary structure of SPI and increase its relative crystallinity, enabling a red shift of amino (-NH₂) groups and a denser structure formation on SPI surface. These results offer valuable insights into the use of SPI/CS complex in the food industry.