Development of control and monitoring systems for wine fermentation

Abstract

A sampling, sparging and monitoring system for fermentation vessels has been designed, constructed and trialled at the Hickinbotham-Roseworthy Wine Science Laboratories using the Ron Potter Red Wine Fermentation Facility. Wine has been successfully sampled throughout two fermentation cycles with approximately 700 litres of must being treated in each case. Grenache grapes were used in both trials. The project was coordinated by Associate Professor Graham Jones of the University of Adelaide whist the design, construction and operation of the analytical system was carried out under the guidance of Associate Professor David Davey of the University of South Australia.

Summary

The goal of winemakers is to maximise the quality of wine provided by the quality of the received grapes. This is determined largely during the fermentation process. Thus one can make a case for automated control to measure wine parameters and to determine if corrective intervention is needed during fermentation to maintain that quality. The project has applied sophisticated monitoring techniques to the fermentation of red wine. Laboratory trials of the equipment for periods of between 12 – 24 hours were carried out followed by fermentation trials over 10 to14 days. Wine sampling was carried out satisfactorily during this time. Successful control software development was also incorporated into the fermentation trials. The monitoring system included sensors for pH, oxygen, redox, conductance, alcohol and colour. Data from these devices shows that additional on-line sample pre-treatment prior to measurement is required for satisfactory results for two sensors, conductance and oxygen. Containment of the oxygen and redox probes needs to be improved if data reflecting low oxygen levels in the wine is to obtained consistently. In off-line experiments, near infrared spectrometric determinations of key fermentation parameters such as reducing sugars and alcohol were carried out with fermentation samples. Trends in NIR values were consistent with other measures such as those from standard wet chemical methods, chromatography and Baume readings.