Online monitoring alcoholic fermentation based on electrical conductivity

To test the applicability of electrical conductivity for on-line monitoring alcohol fermentation process. The relationships between conductivity changes and reducing sugar contents, alcohol contents, or pH values were studied respectively. And the impacts of calcium chloride and ammonium sulfate on conductivity during alcoholic fermentation process were further explored. The results showed that there were certain logical relationships between conductivity changes and reducing sugar or alcohol contents respectively. That is, during the decrease stage of electrical conductivity, the electrical conductivity decreased with the decrease of reducing sugar, while increased with the increase of alcohol contents. The results indicated that conductivity could be used to reflect the contents of reducing sugar and alcohol indirectly. Meanwhile, the contents of alcohol and reducing sugar were in line with the parameters of the end of alcoholic fermentation when the conductivity reached its lowest point, then the end of alcoholic fermentation could be determined. There was a certain linear relationship between pH value and conductivity (the variation of pH value and conductivity were the same 60 h before fermentation.). The variation of conductivity could not be affected by calcium chloride and ammonium sulfate within a certain range. Therefore the conductivity could be applied in the on-line monitoring alcoholic fermentation progress and determining the end point of fermentation.