By Greg Rachon - 22 October 2018

Our work has shown that effective pasteurisation for selected organisms in beer could be achieved at significantly lower PU values than those recommended by the industry. Optimising pasteurisation for different beer styles and microorganisms is likely to result in reduced costs, lower energy utilisation and decreased water waste for breweries. There is also the potential to improve taste as over processing of beverages may result in damage to aroma and flavour compounds. The research has been published in the Journal of the Institute of Brewing.

We used a laboratory-based method to screen 14 common beer spoilage organisms for their ability to grow or survive in two beer styles (a light and a dark coloured beer) and survive a thermal insult. Both beer styles selected for this study had an advertised alcohol content of 4.5% ABV. This is important as factors such as alcohol content, pH and the presence of hop compounds are known to be important in determining microbial growth and beer spoilage.

The viable cell concentration in ale and stout beers was reduced to achieve ‘commercial sterility’ at significantly lower PU values than those recommended by the EBC (European Brewery Convention) Manual of Good Practice. We achieved an 8.7 log reduction in the cell numbers of the selected organisms at just 1.59 PU (pasteurisation units). EBC recommends between 15-25 PU for light and 20-35 PU for dark beers.

Although our study demonstrated that successful pasteurisation was achieved for vegetative cells at a significantly lower PU value than recommended by the EBC Manual of Good Practice, further studies are required to demonstrate the optimal level of pasteurisation for spore-forming bacteria and yeast.

Get in touch to find out how we can help you optimise your beer production process.

Greg Rachon, Project Manager / Research Scientist
+44(0)1737 824298
grzegorz.rachon@campdenbri.co.uk