On-line Monitoring and Control of Fed-batch Fermentations in Winemaking

Area of Science:

• Enology
• Biotechnology
• Process Control

Background:

• Fed-batch fermentation in winemaking maintains low, constant sugar levels.
• This method reduces yeast stress and minimizes undesirable secondary metabolite production.
• Effective implementation requires real-time sugar monitoring and robust control strategies.

Purpose of the Study:

• To implement and evaluate a fully automated fed-batch fermentation system for Saccharomyces cerevisiae in grape must.
• To assess the reliability of on-line sugar analysis and control strategies for winemaking.

Main Methods:

• A laboratory-scale setup was utilized for automated fed-batch fermentation.
• Total sugar levels were monitored in-line using FT-MIR ATR spectroscopy.
• A modified PI controller regulated must feed flow rate to maintain constant sugar concentration (50 g/kg).

Main Results:

• The automated system successfully maintained constant sugar levels.
• Good setpoint tracking and disturbance rejection were observed in fermentations up to four days.
• Occasional yeast sedimentation on the ATR crystal was noted as a challenge.

Conclusions:

• Automated fed-batch fermentation is a viable technique for winemaking, improving control over sugar concentration.
• The developed system demonstrates effective sugar level regulation, reducing cell stress.
• Further optimization of controller parameter adaptation is needed for extended fermentation durations.