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31.
Byoungseung Yoo 《International Journal of Food Science & Technology》2006,41(6):601-608
The steady and dynamic shear rheological properties of Korean glutinous rice flour dispersions were evaluated at different concentrations (4, 5, 6, 7 and 8%). Glutinous rice flour dispersions at 25 °C showed a shear‐thinning behaviour (n = 0.487–0.522) with low magnitudes of Casson yield stresses (σoc = 0.056–0.339 Pa). The magnitudes of σoc, consistency index (K) and apparent viscosity (ηa,100) increased with the increase in concentration. The power law model was found to be more suitable than the exponential model in expressing the relationship between concentration and apparent viscosity. The apparent viscosity over the temperature range of 25–70 °C obeyed the Arrhenius temperature relationship, with high determination coefficients (R2 = 0.982–0.998), indicating that the magnitudes of activation energies (Ea) were in the range of 9.05–11.89 kJ mol?1. A single equation, combining the effects of temperature and concentration on ηa,100, was used to describe the flow behaviour of glutinous rice flour dispersions. Magnitudes of storage (G′) and loss (G′′) moduli increased with the increase in concentration and frequency. Magnitudes of G′ were higher than those of G′′ over most of the frequency range. 相似文献
32.
The rheological properties of wheat flour (WF) mixed with RS type 3 at different concentrations of RS (0, 5, 10, 15, and 20%) were examined. Steady and dynamic shear rheological tests indicated that the magnitudes of consistency index (K), apparent viscosity (ηa,100), dynamic modulus (G′ and G″), and complex viscosity (η*) of the WF–RS mixtures decreased with an increase in the mixing concentration of RS. G′ values of WF–RS mixture samples except for 5% RS as a function of aging time (14 h) at 5°C increased rapidly at initial stage and then reached a plateau region at long aging times. Increasing the RS concentration resulted in the decrease in plateau values. In general, these results suggest that the presence of RS in WF modifies the rheological properties, and that these modifications are dependent on the concentration of RS. The most pronounced changes of viscoelastic properties were observed for WF mixed with 20% RS. 相似文献
33.
Food Science and Biotechnology - The effect of sucrose (0, 10, 20, 30, and 40%) on flow and dynamic rheological properties of xanthan gum (XG) mixed with locust bean gum (LBG) at different mixing... 相似文献
34.
The steady and dynamic shear rheological properties of hydroxypropylated rice starch pastes (5%, w/w) were evaluated at different molar substitution (MS, 0.030‐0.142). The swelling power (35.5‐52.8 g/g) and solubility (8.19‐10.7%) values of the hydroxyproylated rice starches were higher than those of native rice starch (26.6 g/g and 7.78%) and increased with an increase in MS. The hydroxypropylated starch pastes at 25°C showed a pronounced shear‐thinning behavior (n = 0.33‐0.40) with Casson yield stress (σoc = 15.9‐31.7 Pa). The consistency index (K) and yield stress (σoc) values of the hydroxypropylated starch pastes were lower than those of the native starch, and increased progressively with an increase in MS. The apparent viscosity (ηa,500) obeyed the Arrhenius temperature relationship over the temperature range of 10‐55°C; the activation energies (Ea) of the hydroxypropylated starch pastes were in the range of 14.8‐18.5 kJ/mol, i.e. higher than that (14.1 kJ/mol) of the native starch. Storage (G′) and loss moduli (G′′) of hydroxypropylated starch pastes increased with an increase in MS, while tan δ (G′′/G′) values decreased, indicating that G′ rose more strongly than G′′ with increased MS. 相似文献