Optimisation in beer fermentation

Recent growth and popularity of microbreweries has had a significant impact on the market for traditional ales and new beer flavours. 

While the marketing of these products focuses on the artisanal aspect of production, there's plenty of science behind creating a beer of consistently good quality.

Beer producers in Belgium have used 'mixed fermentations' for centuries but it's rapidly becoming more widespread in the brewing industry. This is because multiple yeast species working in harmony can create unique flavour combinations. However, it's hard to understand exactly which species are present and which are dominant at various stages throughout the fermentation. 

Our team at the National Centre of Excellence for Food Engineering (NCEFE) partnered with the Biomolecular Sciences Research Centre to explore solutions for producing a consistent product, particularly for small-scale breweries.  

The challenge

Led by Dr Hongwei Zhang, Dr Susan Campbell and Dr Danny Allwood, the team researched ways to control beer fermentations using mixed cultures - using more than one species of yeast at once. They explored how brewers could improve the efficiency and control of the fermentation stage, for example being able to accurately monitor the yeast's behaviour.

The approach

The team aimed to gain a more detailed understanding of the contributions made by different yeast species during fermentation, with a view to offering brewers a way to control them to achieve the desired results. 

First, the team investigated how single strains of yeast behaved in fermentations on both laboratory scale (5 litres) and using the microbrewery pilot plant at NCEFE (200 litres). This is how most commercial beers are produced, using a single strain of yeast, but it also provides a baseline for that yeast's behaviour. Then the team conducted fermentations using specific mixtures of yeast strains to see how their behaviour changed from when they were used alone and what the effect this had on the finished beer.

The outcome

The team monitored the growth of different yeast strains throughout the fermentation process and what effects this has on key factors in the beer like ABV (alcohol by volume), attenuation (how sweet or dry the finished beer is) and, most importantly, flavour.

A greater understanding of the effects on beer after changing parameters such as yeast species composition and fermentation temperature, provides brewers with a greater degree of control when fermenting with mixed cultures.. All of this ensures that their beers hit their specification consistently, batch after batch.

Impact

The work led to collaborations with several local breweries and the team has hosted special events for microbrewers, at NCEFE. These events covered the basics of microbiology, genetics of yeast strains, how to set up a mini micro lab, and ways that brewers can collaborate with Hallam.

It also led to the appointment of a Doctoral Researcher, Alex O’Brien, who is exploring advanced real-time control and optimisation in mixed beer fermentation, bringing better control, greater efficiency and contributing to one of our four key research themes, ‘Digital connectivity and technology’’. This theme focuses on investigating and applying existing and emerging digital technologies to accelerate research innovations by increasing food system effectiveness and consumer value.

Alex has already successfully demonstrated the colour and taste differences possible simply by adjusting the type of yeast used.

Beyond beer, the technology could have applications to any product fermented using yeast or bacteria, such as cider, kombucha, vinegar, baking or dairy products such as yoghurt. It could also be used in the pharmaceutical industry.