Evaluation of rheological properties of selected salt enriched food hydrocolloids Original Research Article

Rheological properties of hydrocolloids are important for the design and operation of continuous processes such as ohmic heating. Addition of salt to hydrocolloids may be desirable to enhance the efficiency of ohmic heating. A rotational viscometer was used to characterize the flow behavior of pectin, starch, xanthan and carrageenan solutions at four temperatures (20°C, 40°C, 60°C and 80°C) and three concentrations. Salt was added at 1%. Samples were subjected to a programmed shear rate increasing from 0 to 300 s−1 in 3 min, held constant at 300 s−1 for 10 min and linearly decreasing to 0 during 3 min. The power law model was fitted to shear stress vs. shear rate data to obtain the consistency coefficient (m) and the flow behavior index (n) for starch and pectin whereas the Herschel–Bulkley model was used for carrageenan and xanthan. Both m and n were sensitive to changes in temperature and concentration.