Craft Beer's Next Top Yeast Strains

Modern craft beer is faced with a persistent dilemma: the need for innovation in flavour, process, and ingredient selection. This is driven by competition within the craft beer sector and also by consumer demand for novel beers. Indeed, craft beer is increasingly becoming defined by the necessity of novelty. It is now extremely common to find a brand new beer (or three) at many craft breweries in Canada every single weekend, and consumers now expect to be delighted by an unending wave of new beers. 

This presents a significant challenge for craft breweries: how do they deliver consistently on new beers and novel flavours while keeping quality high? One solution is to explore the vast landscape of alternative yeast strains now on the market, in addition to the ever-expanding selection of specialty malts, patented hops, fruit purées, spices, and so on. Careful selection of yeasts is a way for a brewery to make their fruity New England IPA different from the brewery next door, or to create cherry pie flavours to complement an oak aged dark ale. 

Yeast labs employ different strategies to address the demand for new flavours in beer. Some have turned to yeast cross breeding in order to dial in flavour and fermentation profiles of their yeast strains. Yeast suppliers have used yeast’s natural ability to mate to generate hybrid yeasts, for example to combine a reliable Saison strain with a less reliable but more flavourful one, or to eliminate hydrogen sulfide (eggy) flavour from lager yeasts. 

Modern lager yeasts are the product of a hybridization event that occurred hundreds of years ago. Now that the "other parent" has been discovered, the door has been opened to breed new lager yeasts. 

Lager yeast, a hybrid yeast from two different parental species, is ripe for innovation: more than 90% of the world’s beer production is light lager. In 2011, the "other parent", Saccharomyces eubayanus was discovered on a beech fungus in Patagonia (it’s also been found on trees in North America and China). Armed with the genetic stock of lager yeast, yeast scientists now have the  potential to create new lager flavours through breeding. This is something we'd like to explore in the future as lagers grow in popularity among craft brewers. 

Other brewers and scientists are turning to yeasts outside of the Saccharomyces (“normal yeast”) family, and employing these alternative yeasts to target flavour combinations previously unknown to brewing, like the heavy pineapple of a pure Brettanomyces ferment, or the enhanced banana flavour of Torulaspora in a German wheat beer. Many yeast labs and breweries are also tinkering with wild yeasts, perhaps isolated from a perfect autumn apple, or from a verdant forest.  A final option is yeast which was under our noses the whole time: brewing yeasts used in regions with active brewing traditions outside of industrial brewing. Such farmhouse brewing cultures still exist in a surprising range of places: the Fjords of Norway, rugged Lithuania, a flight and several bus rides deep into Russia, or within a Bhutanese valley. 

Intrepid beer ethnologists such as Lars Marius Garshol from Norway and Canada’s own Martin Thibault are discovering and writing about these traditional beer cultures, many of which still have their original yeast cultures. At the centre of the rediscovery of traditional brewing cultures and yeasts is the farmhouse brewing Mecca, the Norsk Kornolfestival in Hornindal, Norway. It is a festival established initially to celebrate the farmhouse brewing traditions of Norway, but growing to attract interest from far-flung brewers, whether they are traditional, homebrewers, or brewing professionals. I was lucky to be invited to attend the festival last year. I witnessed techniques as diverse as Lithuanian stone brewing, malt kilning and smoking using alder wood for a powerfully smoky Norwegian beer called ‘Stjørdalsøl’, and the local style of (tart, tropical, woody) ‘raw ale’ brewing where the beer is not boiled at all but instead lautered through hops and then chilled. In fact, the only commonality among the diversity of beers presented at the festival is the ever-present use of juniper branch infusion in the brewing water. 

Kveik (dried yeast) and farmhouse ale on offer at the Norsk Kornolfestival

Central also to the Kornolfestival is the exchange of kveik: the traditional yeasts of western Norway, maintained for what is reported to be hundreds of years through drying and reuse. At Escarpment Labs, we have been working closely with the Norwegians to isolate and test kveik yeasts. We have found that these yeasts are genetically distinct from other brewing strains, and have many intriguing brewing-related properties: they do not produce phenolic flavours, they can ferment wort rapidly, they produce fruity esters, and they are very alcohol tolerant. Overall this points to kveik being as domesticated as a modern California Ale strain, and that’s an extremely important point: craft brewers expect new yeasts to perform like the standard workhorses do, and so kveik present an opportunity for new and exciting yeasts which aren’t an extreme challenge to manage. Additionally, they can perform at a remarkably wide temperature range (20-40ºC), certainly an attractive feature for homebrewers and for brewers in regions with hot summers typically requiring excessive glycol cooling for fermentation.  

 WLN agar plate of a kveik culture; each different-looking colony could be a different strain of yeast! We don't really know yet how diverse these cultures are. 

We think that traditional and underexplored yeasts like Norwegian kveik and others are a big part of the future of brewing. Since traditional, domesticated yeasts exist in Russia and Lithuania, and who knows where else, we have started referring to these as ‘landrace yeasts’. A landrace is defined as a 'domesticated, locally adapted, traditional variety of a crop', and we think this term applies to traditional brewing yeasts and helps avoid confusion with the ‘farmhouse yeasts’ already associated with Belgian brewing. Modern brewers are now exploring landrace yeasts: several yeast labs have commercialized Norwegian kveik, and the Lithuanian ‘Simonaitis’ yeast is making the rounds among hardcore homebrewers. 

Meanwhile, back at the lab, we have been exploring the use of kveik yeasts in beer: samples have been tested by local homebrewers and extensive amounts of data collection have taken place at the University of Guelph. We have scaled this up to collaborations with breweries, including Guelph’s Royal City Brewing (Pining for the Fjords), Toronto’s Indie Alehouse (Loki’s Garden) and Folly Brewpub (Fjord Fiesta). Consumers are intrigued by the unique flavour profiles and story of these yeasts, and that is driving interest from other breweries. There is even a distillery in Ontario making use of the citrusy flavour, fast fermentation and high alcohol tolerance of a kveik yeast for their whiskey fermentation. 

Overall, there has never been a more exciting period of time for craft beer innovation, and a major component of this is the development and discovery of yeast strains by scientists and yeast suppliers. It’s hard to say what craft beer’s next top yeast strain will be, but I suspect that it is already sitting in a test tube or a farmer’s kitchen as you read this sentence.