Rheological properties of hot pepper soybean-soybean paste

Rheological properties of fermented hot pepper-soybean paste (HPSP) were evaluated at different total solid contents (TS, 43.6-54.7%) and temperatures (10-40C). HPSP samples at 20C are highly shear thinning fluids (n=0.25-0.33) with large magnitudes of Casson yield stresses (106-573 Pa). Consistency index (K) and apparent viscosity (η_a,20) increased with increase in TS. Apparent viscosity of HPSP obeyed the Arrhenius temperature relationship. The magnitudes of activation energy (7.6-20.4 kJ/mole) for HPSP increased with increase in TS. A single equation, combining the effects of temperature and concentration on η_a,20, was used to describe flow behavior of HPSP. The time-dependent model of Weltman was found to be most applicable (R² = 0.97-0.99) for HPSP. Storage (G′) and loss (G″) moduli increased with increase in TS, while complex viscosity (η*) decreased. Magnitudes of G′ were higher than those of G″ over the entire range of frequencies (ω).