Viscoelastic Properties of Coagulating Milk

Abstract

The viscoelastic properties of coagulating renneted milk were studied by a dynamic testing technique. With this technique the dynamic viscosity and elasticity of the milk gel were obtained without affecting the coagulation process. Results are given in absolute units for the coagulation process as a function of coagulation temperature, rennet concentration and concentration of calcium chloride. The shear stiffness modulus of coagulated milk at renneting time corresponding to standard conditions was 30 to 40 pascals. The milk gel, once formed, had a loss factor (ratio of viscous to elastic properties) that was largely independent of experimental conditions such as time of coagulation, calcium chloride concentration and rennet concentration. The ratio of viscous to elastic properties was 0.26. Increased temperature of coagulation increased the loss factor.