The effect of temperature on the colligative properties of food-grade konjac gum in water solutions

This research paper presents the results of tests on the colligative properties of konjac gum chains in water solutions. For this purpose, the measurements of osmotic pressure and intrinsic viscosity of aqueous solutions, in the function of konjac gum concentration and temperature were carried out. The applied methods allowed for the determination of the second osmotic virial coefficients B2, which raised with the increase of temperature. It indicate that increase of temperature causes higher affinity of polysaccharide's chains to water. It was determined, that the osmotic average molecular mass of the konjac gum in non-purified solutions increases with temperature (1.07 × 105-3.80 × 105 g × mol−1). Values of the reduced viscosity linearly increased in range 18-29 dL × g for all temperatures. Received values of the Huggins constant (0.81-1.72) lead that water is poor solvent for konjac gum. The theta (θ) conditions were extrapolated for non-purified solutions − 325 K (52 °C), and interpolated for purified solutions − 307 K (34 °C). Based on the results of tests using the dynamic light scattering, the values of two main relaxation times (fast − 0.4-1.8 ms and slow components − 4300-5500 ms) were determined (the Kohlrausch-Williams-Watts). The obtained autocorrelation functions were characteristic for sol type systems or these which indicate a gel-like structure.