The Electrical Conductivity of Milk—The Effect of Dilution and Temperature

Abstract

The electrical conductivity of milk at various dilutions was measured at different temperatures from 2 to 70°C. The results showed that dilution has only a small influence on the temperature dependence of conductivity. A simple power-law model predicts that the conductivity is proportional to the milk concentration to the power of 0.84 and a two-term model describes the temperature dependency. The overall model has a standard deviation of 0.0067 mS cm−1, which corresponds approximately to 0.1% milk at 2°C and 0.07% milk at 70°C. It was further shown that for less than about 25% milk in water Kohlrausch's law and the Debye-Hückel-Onsager theory can be used to describe the relationship between the concentration, temperature, and conductivity using a representative limiting molar conductivity of milk ions of 75 mS cm2 mol−1.