Analysis of the tendency for the electronic conductivity to change during alcoholic fermentation

Abstract

The observation that the electronic conductivity begins to decease and then increases during alcoholic fermentation was first discovered in our work. To explain the tendency experiments were conducted to investigate the effect of the reducing sugar concentration, ethanol concentration, cell density, pH and ionic concentration. The results showed that the ionic concentration, reducing sugar concentration, cell concentration, pH and especially the ethanol concentration caused a change of the electronic conductivity. From 0 h to 60 h, the ethanol concentration had a significant negative correlation with the conductivity, which decreased with increasing ethanol concentration during fermentation. From 60 h to 68 h, when the ethanol concentration remained unchanged, the total ionic concentration had a significant positive correlation with the electronic conductivity, which increased with increasing ionic concentration (pH value decreases, cell autolysis). Thus, when the electronic conductivity reached its lowest point, the alcoholic content was the greatest. We concluded that it is feasible to directly reflect the change of the ethanol concentration using the change of the electronic conductivity by constructing a mathematical model. The results of this model could be applied for the completely on-line monitoring of the alcoholic fermentation process and for determining the end point of fermentation.