Preparation and characterization of zein-betanin complexes based on two physical modifications: Interaction...

This study investigated the formation of complexes between betanin and zein following modification by heat treatment or ultrasonication to improve the functional properties of zein and the stability of betanin. Structural analysis revealed that physical modification promotes the unfolding of zein, thereby enhancing its binding affinity for betanin. The complexes are primarily stabilized by hydrogen bonding, hydrophobic interactions, and electrostatic forces. Microscopic observations reveal that the modified protein surface exhibits a rough, porous morphology, increasing its specific surface area and thereby providing more binding sites for betanin. The stability of betanin is effectively enhanced, while the complex size is reduced and its distribution becomes more uniform. Functional studies indicate that synergistic modification significantly enhances the emulsifying properties, foaming capacity, and antioxidant activity of zein. Notably, ultrasonication was more effective than heat treatment in promoting zein unfolding, providing more binding sites, and thereby significantly enhancing betanin binding efficiency and the functional properties of the complexes. This study presents a promising strategy for stabilizing natural pigments and incorporating zein into functional foods.