Water-wetting treatment inhibits the swelling behavior of konjac glucomannan powder: A further investigation

Abstract

In this study, a simple and effective water-wetting treatment method was developed for preparing low-swelling konjac glucomannan (KGM). Different water-wetting quantities were applied to native KGM powder, followed by low-temperature drying and sieving to produce samples with low swelling rate. Both Native KGM powder (control) and the KGM powder processed by water-wetting treatment were evaluated for swelling rate, apparent viscosity, dynamic viscosity at various water temperatures, and static rheology. Notably, the swelling rate of KGM-W-65 (optimal treatment group) was quantified as 37.78 % of the control, while other treatment groups (KGM-W-25, KGM-W-45, and KGM-W-85) exhibited swelling rate of 72.3 %, 58.4 %, and 121.5 % of the control, respectively. The apparent viscosity of KGM-W-65 was explicitly stated as 74.7 % of the Native KGM's viscosity (30,293.3 ± 40.41 mPa·s), highlighting the inhibition effect. Additionally, scanning electron microscopy was employed to validate the swelling inhibition effect at the microscopic level. Furthermore, Gaussian fitting of Fourier-transform infrared and Raman spectra revealed that the water-wetting treatment significantly modified the distribution of hydrogen bond types within the KGM powder, a key factor in mitigating the swelling of konjac powder in aqueous systems. Hence, this physical modification offers an industry-friendly method to produce low-swelling KGM.