2026 Volume 27 Issue 3 Pages 33-42
This study investigated the effects of different alkali types on the physical properties of konjac gel using a rotational rheometer. The aqueous solutions of konjac flour were coagulated using four types of alkali (potassium carbonate, calcium hydroxide, magnesium carbonate, and sodium hydroxide) while standardizing the apparent pH, the amount of hydroxide ions, and the heating time. Amplitude and frequency sweep tests were conducted to evaluate the dynamic viscoelasticity of the formed gels. The results revealed that the type of metal ion significantly affected the physical properties despite the uniform pH conditions. K added gel exhibited a high linear limit but a low flow transition index, indicating a hard but brittle structure with a delicate network. Conversely, Mg added gel showed a low linear limit and a high flow transition index, suggesting a tenacious gel. Ca added gel and Na added gel displayed intermediate characteristics, with Ca added gel showing an uneven network structure. The differences in breakdown behavior were strongly associated with the hydration ability of the metal ions (Mg > Ca > Na > K), rather than the metal valence or minor pH variations. These findings suggest that controlling hydration ability enables the creation of konjac gels with diverse textures.
