2.5. Measurement of rheology of polysaccharides

The viscosity of PEP and DPEP solutions at different temperatures was measured using an MCR3302 rheometer. The samples were dissolved in deionized water and prepared into a solution with a concentration of 0.3%. The samples were added to a rheometer plate (50 mm diameter, 100 μm gap) at temperatures ranging from 25°C to 90°C. The variation of the viscosity of the samples with temperature was examined, and the temperature was measured by adding a seal and a drop of methyl silicone oil during the experiment to avoid excessive water evaporation. For each sample, the experiment was repeated three times.

The viscosity of polysaccharide solutions at different pH was investigated using MCR3302 rheometer. PEP and DPEP samples were dissolved in deionized water to a concentration of 0.3%. The pH of PEP and DPEP samples was adjusted respectively to 1.5 and 8.0, using 1 mol/L HCl and 1 mol/L NaCl. The samples were added drop‐wise to a rheometer plate (50 mm diameter, 100 μm gap) at a temperature of 37°C and a shear rate of 0.1 ~ 200 s⁻¹, and the changes in the viscosity of the samples at different pH values were measured in three parallel experiments.