Effect of blending ratio on the compatibility and stability of konjac glucomannan/starch composite systems

A series of complex dispersions and films combining Konjac glucomannan (KGM) and starch in different ratios were prepared. The compatibility and stability of KGM/Starch composite (KS) systems were evaluated using a new horizontal casting device coupled with CCD camera system and Near-infrared (NIR) spectrometer and multiple conventional characterization techniques. The findings from the casting device revealed that when the KGM and starch were combined in a 7∶3 ratio, the dispersion demonstrated isotropic behavior, flowing and diffusing at a consistent speed from the central point to the surrounding area on the casting disc. Additionally, the scattered particles in the NIR reflectance spectrum were evenly distributed at every point, indicating excellent compatibility and uniformity within the dispersion. FTIR and XRD analyses indicated the existence of molecular interactions between the film components, and showed good compatibility between KGM and starch when the KGM content was greater than 50%. The best compatibility was obtained when the KGM content was 70%. The SEM results showed that the increase of KGM content contributed to a smoother and denser microstructure in the cross-section of the KS composite films, especially when the KGM content was 70% (w/w). The rheological results of the KS dispersion further confirmed the formation of a hybrid network structure between KGM and starch. Higher KGM content led to more hydrogen bonds and provided more opportunities for macromolecular chain entanglement. This work will contribute to a better understanding of the interaction mechanism between polysaccharides and starch, as well as provide a new perspective and novel characterization methods to deconstruct the compatibility and assembly structure stability between KGM and starch. It is beneficial for facilitate the application of KGM in the development of denatured food or starch materials, including food texture properties and emulsion stability, and establish a foundation for the diversification of food design tools.