Stability, microstructure and rheological behavior of konjac glucomannan-zein mixed systems

This study aims to investigate the stability, microstructure and rheological properties of konjac glucomannan (KGM)/zein mixed systems in different mixing ratios. A phase diagram was established by centrifugation and visual observation. KGM/zein could form a stable homogeneous dispersion with appropriate mixing formula, and the particle size in mixed systems increased with increasing zein content. During storage, zein particles increased in size but were homogeneously distributed in the continuous phase of KGM without flocculation as observed by confocal light scanning microscopy. The rate of particle size change slowed down with increasing concentration of KGM. Transmission electron microscopy and atomic force microscopy images showed that zein particles were distributed in the KGM molecular network. The mixed systems showed shear-thinning behavior, and the temperature dependence of the viscosity was well-fitted by the Arrhenius equation. Based on dynamic viscoelasticity analysis, the mixed systems showed typical behaviors for entangled polymer solutions. The shift of cross-over frequency of storage (G′) and loss (G″) moduli to higher frequencies with increasing concentration of zein implied the shortening of the lifetime of the temporary entangled junction in the mixed systems.