Physicochemical characterization of konjac glucomannan

Area of Science:

• Polymer Science
• Biochemistry
• Materials Science

Background:

• Konjac glucomannan (KGM) is a polysaccharide with diverse applications.
• Characterizing KGM's molecular properties is crucial for understanding its behavior.
• Existing methods for polymer characterization can be harsh or require derivatization.

Purpose of the Study:

• To characterize commercial konjac glucomannan (KGM) and yeast-derived glucomannan.
• To establish a reproducible method for determining molar mass distribution without polymer derivatization.
• To investigate the rheological properties of KGM solutions.

Main Methods:

• Aqueous gel permeation chromatography coupled with multi-angle laser light scattering (GPC-MALLS).
• Microwave bomb for controlled disaggregation of glucomannan solutions.
• Capillary viscometry, photon correlation spectroscopy (PCS), and rheometry.
• Ellis model for analyzing concentration dependence of zero shear specific viscosity.

Main Results:

• Weight average molecular masses (M(w)) were determined: ~9.0 x 10(5) g/mol for KGM and ~1.3 x 10(5) g/mol for yeast glucomannan.
• Microwave disaggregation provided reproducible molar mass distribution data.
• Degradation upon autoclaving was quantified, enabling Mark-Houwink parameter comparison.
• Concentration dependence of zero shear specific viscosity was analyzed using the Ellis model.

Conclusions:

• A microwave-assisted method offers a non-destructive approach for accurate glucomannan characterization.
• The study provides key molecular and rheological data for KGM and yeast glucomannan.
• Understanding these properties is vital for optimizing KGM applications and processing.