Temperature and storing time influence on selected physical properties of milk and acidophilus milk

Abstract

This article deals with thermophysical parameters as: temperature, thermal conductivity, diffusivity and rheologic parameters as: dynamic, kinematic viscosity and fluidity of milk and acidophilus milk. For thermophysical parameters measurements was used Hot Wire method and for rheologic parameters measurements was used single – spindle viscometer. In the first series of measurements we measured relations between thermophysical and rheologic parameters in temperature range (5–25) °C for milk and acidophilus milk. Relations of all physical parameters of milk to the temperature showed influence of relative fat content. Effect of storage on milk and acidophilus milk is shown in the text. All measured relations for milk and acidophilus milk during temperature stabilisation had linear increasing progress with high coefficients of determination in the range (0.991–0.998). It was shown that increasing relative fat content has decreasing influence on milk thermal conductivity. Relations of rheologic parameters as dynamic and kinematic viscosity to the temperature had decreasing exponential progress, while relation of fluidity to the temperature had increasing exponential shape with high coefficients of determination in the range (0.985–0.994).. Mathematical description of the dependencies is summarised by regression equations and all coefficients are in presented tables.

Keywords

• milk
• acidophilus milk
• thermal conductivity and diffusivity
• dynamic and kinematic viscosity
• fluidity
• temperature and storing time