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article imageKeeping the heat out of a good beer

By Tim Sandle     Jul 7, 2015 in Science
Aberystwyth - One problem with making beer is preventing the yeast from getting too hot. This creates a conundrum because yeast generates its own heat, and the more effectively yeast works the more heat it generates.
To deal with the heat issue, scientists have looked into the issue of keeping yeast cool. The problem is when yeast become hot, the outcome is a change to the taste to the beer.
Yeasts are single-celled fungi, key to the brewing process. Yeasts metabolize carbohydrates to produce ethanol when subjected to low oxygen conditions. The ethanol is then filtrated or distilled to create the alcoholic beverage. Different yeasts are used to produce ales and lagers (the two main types of beer.) Ales tend to be produced at higher temperatures than lagers. Furthermore, the two are distinguished by the type of yeast used. There are ale yeasts (which are quite diverse) and lager yeasts (for which there are fewer types.)
Central to the research is finding out whether the level of nutrients given to yeast during exposure to the hottest temperatures affects how healthy the yeast is during the brewing process. This affects the taste of the beer and the extent of the foamy head.
By using a method called flow cytometry, where lasers are used to scan liquids and assess yeast cell numbers, various levels of food and the food-temperature factors can be assessed and modelled. The method allows the proportion of healthy and damaged cells to be calculated.
The findings are that some types of yeast recover well with nutrients provided during the hotter temperatures; whereas other yeasts recover more robustly without nutrients. Another part of the research is working out why some yeasts survive the rise in temperature and why some perish, with a view to selecting hardier yeast strains. This needs to be assessed alongside the best yeasts for flavor and efficiency.
The research was carried out by food technologists from the Institute of Biological, Environmental and Rural Sciences based at Aberystwyth University. The findings have been published in the journal Environmental Microbiology, with the paper titled “Surviving the heat: Heterogeneity of response in Saccharomyces cerevisiae provides insight into thermal damage to the membrane.”
In related news, based on an analysis of bottles of beer salvaged from an 1840s shipwreck close to the Åland Islands, researchers have succeeded in re-creating the original beer.  
More about Beer, Yeast, lager, ales
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