Science communication: "Microbiology of Beer"
Microorganisms play a crucial role in determining the main characteristics of a beer, such as appearance (turbidity, colour), sensation (carbonation), flavour, and aroma, and there is still a world of microbes to be discovered and used in the production of different beers.
Yeasts are the main microorganisms in beer production, with Saccharomyces cerevisiae (ale-type beers) and Saccharomyces pastorianus (lager-type beers) being the most used. Their widespread use is, among other factors, attributed to their high fermentative power - in other words, they are capable of efficiently converting sugars present in the medium into high amounts of ethanol.
In some types of beer, such as sours, bacteria also play a key role in acidifying the drink and giving rise to flavours and aromas not produced (or produced in smaller portions) by yeasts. Currently, microorganisms are recognized as having a great impact on the characteristics of beer, especially in terms of taste and aroma, by producing volatile compounds.
Lambic beers, originated in Belgium, are an example in which the yeast Brettanomyces bruxellensis releases compounds that give the drink aromatic touches described as 'barnyard' or 'horse sweat', desirable by consumers. Due to their importance in beer production, prospection of new yeasts capable of producing exotic products with commercial value is one of the current research topics in food microbiology with high potential of industrial application. Only recently these unconventional yeasts started to be explored as a way to obtain beers with high quality and sensory complexity, and even low alcohol and caloric contents.
Future research in this area will not only involve new microorganisms’ investigation and application, but will also look for a better understanding of how they shape the aromatic profile of beers, through the study of compounds that arise from their metabolism and biosynthetic pathways.
Winner (General Public category) of the 1st Edition of the “Science Communication in microbiology” contest, Nuno Bourbon (iBB - Instituto Superior Técnico, University of Lisbon).
Translated from the original by Tatiana Pinto and Maria Bonatelli from the volunteer FEMS Translation Team.