Advanced Monitoring and Control of Redox Potential in Wine Fermentation

The reduction-oxidation potential, or redox potential, in a fermenting juice may influence the reactions in the juice and within the yeast cells during wine fermentations. The ability to monitor and control the redox potential at a chosen value by adding air during a red wine fermentation was demonstrated in triplicate at the 100-L scale. The Brix curves and redox potential patterns in the controlled fermentations were compared to those in the un-aerated fermentations. The redox control system consisted of a commercial pH meter with a reduction-oxidation electrode and a custom-designed electronic controller. The study showed the redox potential could be controlled at 215 mV, well above its natural level throughout the fermentation. Control of the redox potential resulted in faster peak fermentation rates and earlier completion of the wine fermentations. Analysis of these fermentation curves using a mathematical model indicated that yeast cell viability and the specific maintenance rate of the viable cells were significantly increased by controlling the redox potential during the fermentation.