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Wine fermentation

Gathering frequent and accurate data will help give winemakers more control over fermentation processes.

The wine industry is one of New Zealand’s key primary industries, with a total export value of $1.86 billion in 2021. Dealing with a large range of environmental conditions including, but not limited to, grape varieties, local, and regional variation of soils, temperatures, daylight, rainfall and other weather, has resulted in a high level of craft in the industry, using winemakers' skills and experience. Economic and efficient control of variables during fermentation would help winemakers produce high quality product. 

Small scale experiments (micro fermentation) undertaken by researchers, such as the Wine Science Group led by Dr Rebecca Deed at the University of Auckland’s School of Chemical Sciences, attempt to address these issues and provide valuable insights back to industry. However, while showing good consistency of results within experiments, a lack of standardisation in volumes, equipment and process parameters during fermentation makes comparisons with other experiments, let alone industrial processes, difficult. 

Weighing samples, to assess fermentation progress from weight loss, is a manual process that can only be done infrequently, but the gas flow can be monitored directly and automatically, to measure temperature, pressure and gas composition. This would allow much more frequent sampling and more accurate monitoring of the fermentation process.

Jonathan Muhl of Southern Institute of Technology has been working with the University of Auckland's team, using engineering data analysis methods. Comparing data generated from gas monitoring with the existing weight loss data helps to identify the effects of different experimental conditions, increasing understanding of the fermentation process in the group's experiments and hence in industrial fermentation processes.

The research has applications in other industrial fermentation processes beyond alcoholic beverages, such as production of dairy products like yoghurts and some pharmaceuticals. The research also benefits Jonathan Muhl's ākonga by providing valuable teaching opportunities in mathematics, design and engineering.