Rheological properties of hot pepper-soybean pastes mixed with acetylated starches

Effect of acetylated starches (acetylated rice starch and acetylated tapioca starch) on theological properties of hot pepper-soybean paste (HPSP) at different mixing ratios of rice flour (RF) and acetylated starch (AS) (10/0, 9/1, 8/2, and 7/3) was evaluated in steady and dynamic shear. All HPSP samples at 25 degrees C exhibited shear-thinning (n=0.31-0.36) and thixotropic behavior with high yield stresses and their steady flow curves were well described by power law and Casson models. The presence of AS resulted in the decrease in consistency index (K), apparent viscosity (eta(a,100)), and yield stress (sigma(oc)), and their predominant decreases were noticed at higher ratio of RE to AS (7/3 ratio). Arrhenius temperature relationship represents variation with temperature in the range of 5-35 degrees C with the high determination coefficients (R-2=0.97-0.99). Dynamic moduli (G', G '', and eta*) values of HPSP samples mixed with AS were lower than those of HPSP with no added AS within the experimental range of frequency (0.63-62.8 rad/sec). Steady and dynamic shear rheological properties of HPSP samples seem to be greatly influenced by the presence of acetylated starch.