Bugs and beer: most of us probably don't see a connection beyond shooing flies away from our pint glasses. But for a group of N.C. State University scientists, bugs may hold the secret to making new, surprising and delicious beers.
That's because yeasts — the single-celled fungi responsible for converting sugar to alcohol in fermented foods like beer and wine — are likely to be found on arthropods like bees, wasps, hornets and beetles, said Anne Madden, a part-time post-doctoral researcher at N.C. State.
If these yeasts could be isolated from bugs and successfully cultivated in the lab, she and NCSU professors Rob Dunn and John Sheppard mused, maybe they could be used to brew new kinds of beer.
Most commercial beer, including craft brews, is made using different strains of two species of yeast, Madden said. Because yeast can contribute significantly to the flavor of beer — as much as 50 percent by some estimates — a new species could mean new flavors for the increasingly crowded beer marketplace.
"There's definitely a market for new yeast and especially these kinds of indigenous strains," said Alex Smith, head brewer at Raleigh Brewing Company. Smith mentioned a North Carolina start-up called SouthYeast that harvests wild yeasts from nature.
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"Especially as the market becomes more competitive, you have to do more to stand out," he said.
Turning to bugs
To find new yeasts, the NCSU researchers first looked at wasps. Wasps have long been known to carry yeasts on their bodies, even providing a winter refuge for the tiny fungi when there are no fruit for them to live on.
It took a couple of months, but Madden and her colleagues successfully isolated and grew a number of species of yeast they found on wasp bodies. Their next challenge was to see if any of these species could be used in brewing beer.
Not all yeasts have the right metabolism to make beer, Madden said. Some are intolerant of the sugars in beer, or die when the alcohol level of their environment surpasses 1 or 2 percent.
The team ran biochemical and genetic tests to help them decide which species to work with, but their choice also resulted from guesswork, Madden said.
Even if the yeast was the right kind to produce beer, it wouldn't necessarily have made great tasting beer.
Wild yeasts often produce funky flavors, like "horse blanket," Madden said. "It's not just about finding the wild yeast but about finding the right wild yeast."
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The right yeast
So the scientists were surprised to find that the very first batch of beer that Sheppard made in his food science lab — an ESB or extra special bitter — from the very first yeast they isolated was drinkable, although very sour.
Experimenting with other recipes for styles like ambers and blondes they found that this same species of yeast was capable of producing honey, apple, floral, and subtle sour notes.
"What's really exciting is that it's oftentimes the same chemical produced by those fruits that are being produced by the yeast," Madden said. "So our body is not taking in these flavors as apple-like, but as 'Wow, this is apple.'"
That means brewers can get those flavors without adding ingredients to beer, which many purists feel should be made with just malted barley, hops, yeast and water.
What may be particularly relevant to brewers is the new yeast's ability to produce sour notes. Sour beer on the market today gets it tang from harmless bacteria, like those used to make yogurt. Those bacteria can easily spread into other barrels and turn those beers sour, which makes many breweries hesitant to make sours at all.
Working with wild yeast can also be challenging. Although the beer is brewed in the same way as beer made with conventional yeasts, the new yeast must be "domesticated," or acclimatized to the brewing environment, to be used reliably in brewing. The standard yeasts used today have been bred for generations for brewing purposes, making them almost like "livestock," said Smith of Raleigh Brewing Company.
The NCSU team debuted its wasp-derived beer at the World Beer Festival in Raleigh last year, and then poured their follow-up, a beer brewed from bumblebee yeast and named "Bumblebeer," at the 2014 Wake County Brewers Expo.
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Sheppard still has bottles of the team's beer in his lab's fridge, handy for curious visitors who want to sip wild beer among the beakers and tanks of a half laboratory, half brewery.
Right now that's one of the few places beer enthusiasts can try the new brews, but that may not be true for long.
Microbial terror
Smith said that there is a growing acceptance of microbes such as bacteria and unconventional yeasts in our food.
"People are embracing kombucha and probiotic yogurt," he said. Both those products use bacteria, or a combination of bacteria and yeast, to produce special flavors and textures. Cheese, chocolate, and bread are all products of fermentation — which does not necessarily produce alcohol — as well.
People are beginning to understand that not all bacteria are germs, and that many can even be good for you, said Madden.
In fact, we've relied on the flavoring power of microbes for a long time, whether we realized it or not, Madden said. Part of the "terroir" of a wine or the distinctness of a certain cheese is likely coming from the microbes in its unique environment.
Bacteria and yeast may be acceptable, but many would draw the line at drinking beer with actual bits of bugs in it.
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"One of the questions is are there ground up bugs in the beer," Madden said. "And there are not."
The team removes the yeast from the insect and then grows it in the lab.
"If you have a bug allergy, there's no concerns," she said. "You can still drink the beer."
