Yeast, the Unsung Hero of Beer
As I peer into the roiling, bubbling cauldron of a fermenter, I can’t help but be mesmerized by the sheer magic unfolding before my eyes. This tiny, unassuming fungus – yeast – is quite literally the backbone of the beer we all know and love. But its impact goes far beyond the fizzy, mood-altering beverage we sip on. In fact, one could argue that yeast has done more to shape human history than any other organism, save for humans themselves.
The old adage that “brewers make wort, but yeast makes beer” hints at the central, almost mystical role this microscopic creature plays in the brewing process. As it gobbles up the sugars in the wort, yeast unleashes a dizzying array of chemical reactions, raising the temperature, releasing clouds of carbon dioxide, and producing the all-important ethanol that gives beer its signature kick.
Yet, the true marvel of yeast lies in its ability to transform that simple “breakfast tea” of sugary wort into the complex, aromatic, and flavorful beverages we recognize in our cans and glasses. As Owen Lingley of Imperial Yeast puts it, “Flavor compounds are equally important in creating a quality of beeriness.” From the fruity esters in Belgian ales to the spicy phenols in Bavarian weizens, yeast is the unsung hero that brings the magic of fermentation to life.
The Evolution of Yeast: From Traditional to Technological
The journey of yeast in the brewing world is one of constant evolution – a dance between the traditional and the technological, the natural and the engineered. For centuries, brewers have carefully guided the development of yeast strains, coaxing out unique flavor profiles and fermentation characteristics through selective repitching and incremental changes.
But in recent years, a new era of yeast innovation has emerged, driven by cutting-edge biotechnology and the insatiable quest for ever-more distinctive and captivating flavors. In Northern California, a trio of researchers at UC Berkeley founded a company, Berkeley Yeast, that specializes in engineering next-generation yeast strains. These strains boast remarkable capabilities, from producing specific terpene profiles to eliminating the dreaded diacetyl.
Meanwhile, in the Pacific Northwest, the team at Imperial Yeast is taking a more traditional approach, nurturing their flock of fungi entirely organically and preserving newly-discovered strains through time-honored methods. The contrast between these two paths – the traditional and the technological – reflects the age-old push and pull that has defined the brewing industry for millennia.
The Magical Transformation: Yeast’s Biochemical Dance
To truly understand the power of yeast, one must delve into the intricate dance of biochemical reactions that unfold during fermentation. As the yeast cells consume the sugars in the wort, they embark on a complex metabolic journey, producing a kaleidoscope of flavor compounds that shape the character of the final beer.
At the onset of fermentation, the yeast first indulges in a feast of the simplest sugars, building up their cell walls and preparing to regulate the flow of nutrients in and out of their bodies. Then, as they near the end of their fermentation, they begin to transform those precursor compounds into the esters and phenols that give beer its distinctive flavors and aromas.
“In Belgian beers and Bavarian weizens, these compounds are the most striking, but they exist in all beers, even lagers, filling out the flavor profile with little daubs of fruit and spice,” explains Lingley.
But the story of yeast’s impact doesn’t end there. The selection of the yeast strain is a crucial factor, with some strains being more neutral (like the ubiquitous Chico strain) and others more expressive, like the POF strains that lend a spicy, clove-like character to certain styles. Additionally, the brewing process itself – temperature, fermentation geometry, and pitch rate – can all influence the yeast’s behavior and the flavor compounds it produces.
The Quest for Flavor: From Natural to Engineered Yeast
As the craft beer revolution has unfolded, brewers have become increasingly obsessed with the pursuit of bold, distinctive flavors. And yeast, once the unsung hero, has now taken center stage as a key player in this quest.
The story of the Boddington strain is a prime example of how an overlooked yeast can suddenly become a hot commodity. This soft, fluffy strain, descended from an English brewery, has gained incredible traction in recent years due to its ability to biotransform hop terpenes, enhancing the perception of fruitiness – a prized characteristic in the world of juicy, hazy IPAs.
But the search for novel flavor profiles has also led to the rise of genetically engineered yeast strains. Berkeley Yeast, for instance, has developed strains that can produce specific terpene profiles, replicating the flavors of hops or even melons, without the need for dry-hopping. They’ve also created a revolutionary strain that doesn’t produce diacetyl, a compound that can impart an undesirable buttery flavor.
The Canadian yeast company Lallemand, on the other hand, has taken a different approach, genetically modifying a Saccharomyces strain to produce lactic acid. This “Sourvisiae” yeast has become a game-changer for breweries looking to create sour and acidic beers without the hassle of traditional kettle-souring methods.
The Kveik Conundrum: Nature’s Gift to the Brewing World
While the world of engineered yeast is undoubtedly exciting, nature has its own surprises in store for the brewing community. One of the newest and most intriguing additions to the yeast pantheon is the family of strains known as kveik, hailing from the rugged landscapes of Norway.
These kveik yeasts possess a dazzling range of flavor capabilities, from producing a kaleidoscope of fruity esters to a complete lack of any discernible flavor at all. “We ran fermentation tests at 60-64 degrees, 64-68 degrees, 68-70 degrees, and all the way up to 90 degrees,” says Lingley of Imperial Yeast, “and they’re very different beers.”
The versatility of kveik yeasts doesn’t end there. Some brewers are even experimenting with using them to create lager-like beers, fermented at ale temperatures and exhibiting the characteristic crispness of their lagered counterparts. Parker Rush of The Narrows in Tacoma, Washington, recently brewed a “Pseudolager” using kveik yeast, and was amazed at how bright and lager-like it turned out in just 17 days – a fraction of the time a traditional lager would take.
The kveik conundrum represents the eternal push and pull between the natural and the engineered, the traditional and the technological. As the brewing world continues to evolve, it’s clear that both approaches have a role to play in shaping the future of beer.
The Future of Beer: Embracing Yeast’s Endless Possibilities
As I reflect on the journey of yeast in the brewing world, I can’t help but feel a sense of excitement for the endless possibilities that lie ahead. The landscape of yeast innovation is rapidly expanding, with laboratories and startup companies pushing the boundaries of what we thought possible.
Whether it’s the organic, time-honored methods of Imperial Yeast or the cutting-edge genetic engineering of Berkeley Yeast, one thing is clear: the quest for flavor is just beginning. As Nick Harris, one of Berkeley Yeast’s co-founders, eloquently explains, “The way it works is DNA gets turned into RNA and RNA turns into protein and proteins can make small molecules.” This ability to precisely control the expression of specific genes and the production of desired flavor compounds is a game-changer for the brewing industry.
Yet, even as we embrace the technological advancements, we must not forget the value of the natural and the traditional. The kveik yeasts, with their remarkable adaptability and unique flavor profiles, serve as a reminder that sometimes the most fascinating discoveries can come from simply exploring the wonders of nature.
As I gaze once more into the bubbling cauldron of the fermenter, I can’t help but feel a sense of awe and anticipation. The future of beer is being shaped by the endless possibilities of yeast, and I, for one, can’t wait to see what new and exciting flavors will emerge from this ever-evolving landscape. Who knows, perhaps the next great innovation is just waiting to be discovered, right here at The Up and Under Pub.
