Degraded konjac glucomannan by γ-ray irradiation assisted with ethanol: Preparation and characterization

60Co γ-ray irradiation assisted with ethanol pretreatment was utilized to prepare degraded konjac glucomannan products with well-dispersed low molecular fractions and white color. The molecular weight decreased from 1.4 × 106 to 6 × 105 at the dose of 3.6 kGy irradiation with 50% ethanol pretreatment. The properties and structure were analyzed by Fourier-transform infrared spectroscopy (FT-IR), colorimeter, dynamic light scattering (DLS), differential scanning calorimetry (DSC) and rheology. The chemical structure of degraded KGM was slight changed, while the thermal stability and whiteness enhanced for ethanol processed samples. DLS observation showed products had mono-model distribution. The zero-shear rate viscosity (η0) decreased from 139.8 Pa s to 2.928 Pa s as the irradiation increased up to 6.0 kGy. In conclusion, 60Co γ-ray irradiation assisted with ethanol pretreatment will be a promising method to produce high quality KGM with low molecular weight to meet the practical production needs.