Studies on the Molecular Chain Conformation and Morphology of Konjac Glucomannan in Aqueous Solution
The molecular chain conformation of konjac glucomannan (KGM) was studied by multi-angle laser light scatter (MALLS) and differential refractive index detector (RI) with GPC. The absolute Molecular weight (MW), toot-mean-square ratio of gyration (1/2), second viral coefficient and molecular weight distribution (MWD) were 5.38×105g•mol-1, 201.9 nm, 1.18×10-2 mol mL g-2 and 1.07, respectively by MALLS when KGM concentration was 1 mg mL-1. RI with GPC was used to determine MW and MWD of five different concentration of KGM aqueous solution. MW varied from 7.46×105 to 6.34×105 g•mol-1 when KGM concentration ranged from 0.05 to1.00 mg mL-1, but MWD was all about 1.06. Mark-Houwink equation was established as η=5.19×10-3 MW 0.92. The morphology of konjac glucomannan was observed by atomic force microscope (AFM), transmission electron microscope (TEM) and scanning electron microscope (SEM). The image showed that KGM in aqueous solution was displayed with reticulation. The results obtained show that KGM in aqueous solution is displayed with reticulation; molecular chain is rigid; molecular scale increases with decreasing KGM concentration in aqueous solution.