Single molecular chain geometry of konjac glucomannan as a high quality dietary fiber in East Asia

The chain geometry and parameters of konjac glucomannan (KGM) were studied by using laser light scatter (LLS), gel permeation chromatography (GPC) and viscosimetry. The weight-average molecular weight ( M w), root-mean-square ratio of gyration (〈 S 2〉 1/2), second viral coefficient ( A 2) and polydispersity index ( M w/ M n) were 1.036 × 10 6, 105 ± 0.9 nm, (−1.587 ± 0.283) × 10 −3 mol mL g −2 and 1.015 ± 0.003, respectively. Mark–Houwink equation was established as [ η ] = 5.96 × 10 - 2 M w 0.7317 , and the molecular chain parameters were as follows: M L = 982.82 nm −1, q = 27.93 nm, d = 0.74 nm, h = 0.26 nm, L = 1054.11 nm. To confirm the results above, KGM was observed by using atomic force microscope (AFM) and transmission electron microscope (TEM). The physical image showed directly that the KGM molecular was an extending semi-flexible linear chain without branches, and the molecular dimension conformed to the parameters above. Therefore, the image of molecular chain geometry confirmed the deduction drawn by Mark–Houwink equation and molecular chain parameters magnificently.