Yeast: Why People (and Flies) Love Beer

Do you remember the first time you tried beer? There is probably not a single child who said "that's good!" after being permitted a sip of that forbidden amber drink. So why have adults developed a taste for the bitter and bubbly? Researchers are now arguing that it's actually yeast that drives the subtle beer flavors and aromas we learn to enjoy.

"The importance of yeast in beer brewing has long been underestimated," researcher Kevin Verstrepen said in a recent statement. "But recent research shows that the choice of a particular yeast strain or variety explains differences in taste between different beers and wines."

He argues in a study recently published in the journal Cell Reports that yeasts may even be responsible for much of a beverage's "terroir," the characteristics of a particular growing area's flavor profile. Brewers have long associated terroir with the soil where grapes or hops grow, but it may have much more to do with what microbes are used to facilitate the fermentation and carbonation of beers and sparkling wines.

Nature World News similarly reported how another recent study determined that local microbes and how they interact with yeast cells can potentially impact the quality of sake - a Japanese rice wine - more than the active brewing process.

Now, this latest study reveals that not only does yeast affect quality and flavor, but the attractiveness of a drink too.

Researchers determined that fruity volatiles - a type of ester chemical compound - produced by yeast cells are highly appealing to fruit flies and humans alike. This attraction helps otherwise immobile yeast cells catch a ride to new food sources.

According to the study, a small experiment determined that it was these esters that make beer attractive to flies. Beer made with mutant yeast that cannot produce volatiles would be both bland and unattractive.

"Knowing that esters make beer taste good, it seems that the same flavors that allow us to enjoy our beer probably evolved to attract flies and to help yeast disperse into broader ecosystems," explained Emre Yaksi, the researcher who led the experiments.

The team believes that their findings have far-reaching implications, potentially explaining how microbes will work to similarly attract beneficial transporters, just like flowers attract pollinators.

"There's a lot to be learnt about the mutualism between insects and microbes, and some of what we find may have implications in agriculture and medicine," added researcher Luis Franco.