Electrical conductivity is used as a simple method to monitor demineralization of food systems during conventional electrodialysis treatments. However, during bipolar membrane electroacidification, the H+ generated at the bipolar membrane, have a higher conductivity contribution in comparison with all other cations. The objective of the present work was to develop an equation correlating conductivity and temperature to the demineralization rate in cheddar cheese whey during bipolar membrane electroacidification treatment. It appeared that conductivity data were not directly correlated with experimental dernineralization rate. Thus a second order polynomial equation appropriate for whole and skim whey, was developed in order to predict demineralization rate (D) as a function of conductivity (C) and temperature (T): D = 153.42 - 64.45C + 5.55T + 2.97C(2) - 0.03T(2) (R-2 = 0.946). Mathematical models were also calculated from data of diluted whey solutions and these equations allowed evaluation of dilution phenomenon due to dead volume in electrodialysis cell prior to electroacidification. This work will allow the use of conductivity and temperature measurements to indicate, more precisely, the dernineralization rate of cheddar cheese whey during electroacidification with bipolar membrane. (c) 2005 Elsevier B.V. All rights reserved.