Evaluation of rheological properties of selected salt enriched food hydrocolloids

Rheological properties of hydrocolloids are important for the design and op eration 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 now behavior of pectin , starch, xanthan and carrageenan solutions at four temperatures (20 degree sC, 40 degreesC, 60 degreesC and 80 degreesC) and three concentrations. Sal t was added at 1%. Samples were subjected to a programmed shear rate increa sing from 0 to 300 s(-1) in 3 min, held constant at 300 s(-1) for 10 min an d 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 (II) for starch and pectin whereas the Herschel -Bulkley model was used for carrageenan and xanthan. Both m and n were sens itive to changes in temperature and concentration. (C) 2001 Elsevier Scienc e Ltd. Ail rights reserved.