Colloidal stability and rheological properties of sesame paste

Particle size and temperature effects on the colloidal stability and rheological characteristics of sesame paste, which is a kind of protein–oil suspension, were investigated. Multimodal particle size distribution determined using laser-scattering analyzer was observed for paste samples and it was detected that colloidal stability of sesame paste was improved by decreasing the median particle size below 5 μm. A decrease in the storage temperature also caused the increase in the colloidal stability. Shear thinning and thixotropic behaviors were observed for sesame paste. Dynamic shear test showed that elastic structure of sesame paste changed regularly to viscous behavior with decreasing particle size and the magnitudes of the storage (G′) and loss (G″) moduli increased with frequency. Whiteness (L-values) of sesame paste decreased as with the reduction of particle size.