The contribution of the various components in cow's milk to its electrical conductivity has been studied using the technique of admittance spectroscopy. Measurements at 100 kHz and 8 degreesC confirm previous observations that the milk conductance is predominantly determined by the salt fraction. Lactose showed very little effect on the conductivity, while the presence of fat resulted in a decrease in the milk conductance with increasing fat content. Sodium caseinate possessed a very low conductance; nevertheless, we suggest that the physical and chemical nature of the casein micelles can influence the overall milk conductivity. (C) 2003 Elsevier Ltd. All rights reserved.