Synergetic degradation of konjac glucomannan by γ-ray irradiation and hydrogen peroxide

Konjac glucomannan (KGM) samples were irradiated with 60Co γ-rays with a radiation dose of 50 kGy in the presence and absence of hydrogen peroxide. The average molecular weight (Mw) and polydispersity index (PDI) of untreated and degraded samples were measured by gel permeation chromatography (GPC), revealing that γ-rays and hydrogen peroxide had a synergetic effect on degradation. Structures of untreated and degraded products were characterized with ultraviolet–visible (UV) and Fourier-transform infrared (FT-IR) spectroscopies, and X-ray diffraction (XRD). Results showed that there was no significant change in the main chain of KGM following degradation, although the crystallinity of KGM decreased. A synergetic effect of γ-rays and hydrogen peroxide was also found in the structural characterization of KGM. The physical properties of KGM changed markedly following degradation, which may increase its application potential. The mechanism of degradation of KGM in the presence and absence of hydrogen peroxide was also investigated.

► KGM was degraded by γ-ray irradiation and hydrogen peroxide for the first time.
► Provide a new way to prepare monodisperse KGM oligosaccharides without purification.
► The mechanism of KGM synergetic degradation was discussed for the first time.