Study on stabilizing mechanism of konjac glucomannan in tea infusions

The stabilizing mechanism of konjac glucomannan (KGM) in tea infusions was studied using a convertional transmission electron microscope (TEM), scanning electron microscope (SEM), ethanol sedimentation, and other methods. As a result, many water-soluble complexes among the KGM molecules and tea components such as thearubigins (TRs), theaflavins (TFs), total catechins (TC), and tea polyphenols (TPP) were obviously formed in tea infusions with addition of KGM. The aggregations of tea components, which caused tea cream down, were decreased because of KGM addition and the stability of suspended particles in tea-KGM infusions was enhanced. These findings suggested that the strong adsorption happened among KGM and tea components and particles through strong hydrogen bonding functions. Molecular weight of KGM in tea infusions was smaller than that in water solution. In water solution, it was 4.83 x 10(5), but in black tea infusions 3.41 x 10(5), and in oolong tea infusions 3.51 x 10(5). The experiments also revealed that the tea-KGM infusions had stronger antielectrolyte coagulation capacity and the static electrification action exists among molecules of tea infusions. These findings indicated that KGM could be a useful stabilizer for stability of the tea infusions.