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.

Keywords:

• Electrical conductivity
• Milk
• Dilution
• Temperature

Acknowledgment

The authors wish to acknowledge the grant from The Swedish Agency for Innovation Systems. We should also like to thank Professor Rolf Sundberg for valuable comments to the article and advice in the model formulation.