Rheological behaviors of ginseng extracts in steady and dynamic shear

The steady and dynamic Theological properties of ginseng extracts were evaluated at 60.6-69.8% total solid contents. Ginseng extracts at 20C showed a very low shear-thinning flow behavior (n = 0.94 - 0.98) with low consistency index (K = 0.39 - 5.02 Pa.sⁿ). Over the temperature range of 5 - 50C, the magnitudes of K and apparent viscosity (η_a,100) decreased with increase in temperature. The apparent viscosity obeyed the Arrhenius temperature relationship; the activation energies for flow of ginseng extracts were in the range of 56.9 - 85.9 kJ/mol. The exponential type relationship between total solids and apparent viscosity was found to be more suitable than a power type relationship. Viscosity data at various temperatures could be reduced to a composite viscosity curve using a reduced apparent viscosity (η_aR). Magnitudes of storage (G') and loss (G") moduli increased with increase in total solids. Magnitudes of G" were much higher than those of G' over the entire range of frequencies (ω) with the high dependence on ω.