Effects of Temperature on Time Dependent Rheological Characteristics of Koumiss

Abstract

The rheological properties of koumiss were investigated at different temperatures (4, 10, and 20°C). Experimental shear stress-shear rate data were fitted to different rheological models. The consistency of koumiss was predicted by using the power-law model since it described the consistency of koumiss best with highest regression coefficient and lowest errors (root mean square error and chi-square). Koumiss exhibited shear thinning behavior (n<1). The flow activation energy for temperature dependency of consistency was 25.532 kJ/mol, and the frequency constant was 2.18×10-7 Pa.sn . As the temperature increased the time dependent thixotropic characteristics of koumiss decreased.