Preparation and characterization of konjac glucomannan microcrystals through acid hydrolysis

Konjac glucomannan (KGM) was treated by a facile acid hydrolysis to fabricate KGM microcrystals. At the first day of hydrolysis, KGM microcrystals were formed. With the extension of hydrolysis time, the particle size of KGM microcrystals decreased from 45 μm to 15 μm. In addition, compared with native KGM, the morphological, physicochemical, crystalline, and thermal properties of KGM microcrystals changed significantly. SEM images showed the irregular shapes and rough surfaces of KGM microcrystals as well as the smooth surface of native KGM. FTIR measurements revealed the cleavage of carbonyl groups in KGM microcrystals. XRD curves clearly presented the crystalline structure of KGM microcrystals, and the relative crystallinity increased to approximately 50%. DSC analysis showed that microcrystals had a better thermal stability than native KGM, which could be preferably used as reinforcement in the biocompatible material at high temperature.