Dynamic mechanical properties of milk and milk gel

Abstract

The dynamic mechanical properties of milk and milk gel were examined as functions of frequency, temperature, and concentration. The real and imaginary parts of the complex rigidity G′ and G″ measured at various frequencies were found to be superposable onto a single set of master relaxation curves by performing the horizontal shift along the logarithmic frequency axis except for milk gel which were prepared at different temperatures. The results show that the rigidity of milk gel depends on the concentration of milk C in such a way that G^* ∝ C². It was found that G′ depends on the temperature as G′ ∝ T. It was also found that the complex rigidity of skim milk solution depends on the angular frequency ω in such a way that G^* ∝ ω ^1/2. The dependence of G^* on frequency seems to indicate the formation of structure by casein micelle in solution.