Abstract
The effects of temperature on hydrogenated yolk lecithin (HYL) dispersion were determined based on examination of flow curves and shear-jumps in oscillation rheometry, particle size, polarized microscopy and DSC.
Based on the results obtained, the following conclusions were drawn;
1) Temperature dependence of complex viscosity (η*) for HYL-40 and HYL-60 dispersions prepared at 40°C and 60°C respectively as incubation temperatures indicated features characteristic of complex viscosity at 50°C, this temperature being related to that of the gel-liquid crystal transition of HYL, HYL-50 dispersions showed no particular features at 50°C.
2) HYL-dispersions prepared at 40°, 50°, and 60°C showed rheopexy properties at 40° and 50°C.
3) η* vs. time curves of HYL-dispersions at ω = 0.1 rad/s indicated complex viscosity in the rheopexy region to increase with decrease in temperature owing to liquid crystalline formation of a bilayer in HYL.
4) Based on the time-dependence of complex viscosity(η*) for HYL-dispersions as determined from shear-jump and change in the liquid crystalline bilayer of HYL, the method for flocculation was elucidated.
