Effect of Amylose Content on Stability of Maize Starch-Tea Polyphenol Emulsion Gels

Abstract

Maize starch with different amylose contents and tea polyphenols (TP) were co-heated to prepare maize starch-TP hydrogels, and the hydrogels were used to stabilize food-grade emulsion gels. The effects of amylose contents on the microstructure, rheological behavior and emulsification properties of maize starch-TP hydrogels and emulsion gels stabilized by it. The results showed differences in the amount of retained TP among maize starch hydrogels with different amylose contents and consequently in the microstructure of maize starch-TP hydrogels. As the amylose content decreased, the size of droplets in emulsion gels stabilized by maize starch-TP hydrogels decreased, and the viscosity and viscoelasticity of emulsion gels increased, suggesting the formation of network structures in emulsion gels. As observed by cryo-scanning electron microscopy (cryo-SEM), a structurally compact network matrix was formed in emulsion gels with decreasing amylose contents. The hydrogel network matrices could adhere to oil droplets, thereby hindering their coalescence, and maintaining the stability of emulsion gels for a long time. This study can provide a theoretical foundation for developing starch-based emulsion gels and delivery vehicle for bioactive substances in the food industry.

Keywords

• maize starch; tea polyphenols; emulsion gel; microstructure; rheological behavior