This article is about sex and beer. Don’t say IFLScience never gives you anything.
Okay, well it’s not the kind of sex you’re used to, well I hope not anyway. We’re talking about yeast sex. Now that may leave you somewhat deflated, but this yeast hanky panky could bring us new types of beer that take us beyond the homogeneous tastes of lager that currently line supermarket shelves. The findings are published in the September 25 edition of Applied and Environmental Microbiology.
Unlike lager, ales vary significantly not only in taste but aroma and appearance, too. The narrow range of flavor has been attributed to a lack of genetic diversity in the yeasts used during fermentation, all of which are slight variations of the species S. pastorianus. Interestingly, genetic studies have found that all these strains are the result of just two crosses between parental species.
These independent hybridization events, involving the species Saccharomyces cerevisiae and S. eubayanus, gave rise to two distinct yeast genotypes, Saaz and Frohberg. It is from these that all commercially available strains are derived.
Scientists therefore wondered whether creating a greater breadth of yeast strains could be key to spicing up the range of aromas available in lagers. To achieve this, they selected six strains of S. cerevisiae and two of S. eubayanus and experimentally manipulated their growth environment in order to try and encourage interspecies breeding.
“We were able to get some serious sexual action between our yeasts, which resulted in hundreds of new lager yeast strains,” lead researcher Kevin Verstrepen from the University of Leuven, Belgium, said in a statement. They then tested 31 novel strains out in small, lab-scale beer fermentations, and disappointedly some of them produced beer that was pretty rank. But 10 of them showed potential, producing diverse aroma profiles and growing speedily under industrially relevant conditions. So they selected four of these and put them through pilot-scale fermentations.
“Two were magnificent,” recalled Verstrepen. “They fermented more quickly than the commercially used reference lager yeast that we compared them to, and they produced really nice flavors.”
Importantly, they found that their new hybrids generated aroma profiles that differed significantly to those used today, and one in particular was especially fruity.
“This means that it now becomes possible to make lager beers that, like ale beers, are more different from each other, and this [sic] without the need to extensively change the production process.”
Whether or not we will see any of these exotic new lagers on the shelves any time soon hasn’t been speculated by the researcher, but if we do, we can thank this group’s weekly in-lab beer-tasting sessions, which resulted in one scientist’s lightbulb moment. Methinks if all labs were like this, there would be a lot more scientists around the world, albeit with all that beer, they probably wouldn’t get much work done.
