keywords: Viscosity, electrical conductivity, electric potential, pH, temperature
In this study, four physical parameters (viscosity, electrical conductivity, electric potential and pH) were determined for three milk samples obtained within Benin City. The study was conducted with the aim of establishing the interrelationship between these physical parameters of interest with change in temperature of the milk samples. Viscosity measurements were made by means of a Ubbelohde Viscometer which was made in Germany. Electrical conductivity measurements were performed by means of electrical conductivity meter (HACH, CO 150, USA), while the measurements of pH and electric potential were conducted by means of pH and Electric Potential (mV) meter (SUNTEX, SP-701, USA). The results obtained showed that the milk samples exhibited Newtonian behavior with viscosity decreasing as the temperature was increased. On the other hand, the electrical conductivity and electric potential values were observed to increase with increase in temperature as expected generally for liquids. For pH, increase in temperature resulted in decrease in pH values which is an increase in acidity. The viscosity, electrical conductivity, electric potential and pH values of the milk samples were in the range from 1.74 – 56.14 mPas, 1.31 – 6.07 mS/cm, -153– -61 mV and 6.4– 8.3, respectively. The correlation of viscosity with electrical properties was tested. The Arrhenius model was investigated to describe the temperature dependence of the viscosity of the milk samples resulting in activation energy for flow between 5.56–24.85 kJmol-1 within the temperature range of study.