earticle

영어

The effect of five commercial gums (carboxylmethylcellulose, CMC; guar gum, GG; hydroxypropylmethyl-cellulose, HPMC; locust bean gum, LBG; and xanthan gum) at a concentration of 0.25% on the rheological properties of rice flour (RF) dispersions was investigated in steady and dynamic shear. The steady shear rheological properties showed that RF gum mixture dispersions (5%, w/w) at 25℃ had high shear-thinning flow behavior (n=0.20-0.31) exhibiting a yield stress. Magnitudes of consistency index (K), apparent viscosity (??,100), and Casson yield stress (?oc) of RF-gum mixtures were much higher than those of RF dispersion with no added gum (control). Activation energy values (6.67-10.8 kJ/mole) of RF-gum mixtures within the temperature range of 25-70℃ were lower than that (11.9 kJ/mole) of the control. Dynamic rheological data of log (G', G") versus log frequency (w) of RF-gum mixtures had positive slopes (0.15-0.37) with G' greater than G" over most of the frequency range (0.63-63 rad/sec), demonstrating a frequency dependency. Tan ? (G"/G') values of RF-gum mixtures, except for xanthan gum, were much higher than that of the control.