Repro or Retro?

At the core of almost every hops-forward lager, Pilsner, or otherwise brewed in America is one of two families of industrial yeast strains.

Stan Hieronymus Nov 9, 2016 - 12 min read

Repro or Retro? Primary Image

Earlier this year, brewers at the Carlsberg Research Laboratory in Copenhagen demonstrated just how many original ingredients and other contributors to the brewing process must be replicated to perfectly, or almost perfectly, reproduce a nineteenth-century beer. This small-batch repro beer illustrated that the term retro beer does not refer only to brands such as Pabst that lean heavily on nostalgia.

First, a Bit of History

Lager brewing likely began in Bavaria in the fourteenth or fifteenth century, although neither the date nor the geographic region is known with any certainty. Founded in 1842, the Carlsberg brewery (Copenhagen, Denmark) used yeast first provided in 1845 by Gabriel Sedlmayr of the Spaten brewery in Munich. In 1875, Carlsberg Founder J. C. Jacobsen established the Carlsberg Research Laboratory and in 1876, the Carlsberg Foundation to manage the laboratory. The foundation owns about one third of the Carlsberg Group, the fourth largest brewing company in the world.

Because of discoveries that Emil Christian Hansen made in that lab, Carlsberg became the first brewery to sell beer made with a pure yeast culture. Carlsberg shared both the yeast and the technology, allowing breweries around the world to brew more consistent lager beers and on a much larger scale. The brewery first bottled beer made with this pure culture in the fall of 1883, and 130 year-old yeast cells collected from an early bottling (“We can’t say exactly when,” says Erik Lund, head brewer at the research center) became the center of “The Re-Brew Project.”

“What we want to do is to get our place in history, a fair place,” says Bjarke Bundgaard, who works in marketing, explaining why Carlsberg invested a tidy sum in The Re-Brew Project, which doubled as a celebration of the lab’s 140th anniversary. To reproduce a beer that tasted as it might have in 1883, Carlsberg contracted to have an heirloom barley variety called Gammel Dansk (“Old Danish”) grown again and had it floor malted at a whiskey distillery. Some of the malts were then kilned at the pilot brewery to replicate Munich, caramel, and chocolate malts.


The beer was brewed on a 2-hectoliter pilot system that is otherwise used for process optimization for Carlsberg beers and trial development for the Jacobsen line, Carlsberg’s specialty brand. Brewers added mineral salts to distilled water to match the water profile found in 1883 records and used Hallertau Mittelfrüh hops for bittering and flavor. Although brewing records indicated the bitterness level might have been lower, Lund said the target was 15 to 18 IBUs. (Modern Carlsberg is about 22 IBUs.)

The pilot system has an adjunct tank, so Lund and his staff were able to perform a triple decoction mash. For primary fermentation, they opened the top of the tanks to replicated 1880s open fermentation. The beer lagered almost two months.

The beer—Father of Quality Lager—which could best be described as a sweetish Vienna lager (5.8 percent ABV), was served this past May with particular pomp and circumstance, first tapped in an afternoon ceremony and later at an evening dinner attended by Denmark’s crown prince. Plans are to pour more at select locations around the world, including New York’s Brooklyn Brewery in August.

Brooklyn and Carlsberg are partners in two brewing ventures in Scandanavia, and Brooklyn Brewmaster Garrett Oliver attended the May events. “To taste this right now as a re-creation is a kind of fascinating thing,” he said. “This [1883] is when things started to get kind of good. Before that, you never quite knew [about the taste or quality of the beer]. This was the start of knowing things, which as a brewer, I find really interesting.”


The view from inside the process was as intriguing. “It was more than an escape from day-to-day work,” Lund says. “Before this was done, we could not know what the beer was like. The number one thing I learned was beers at that time were actually pretty good, if you could follow good manufacturing practices and get good raw materials.”

The American Connection

Brewers in America, most of them German immigrants, began to brew with lager yeast as early as 1840 and likely had access to pure strains not long after 1883. Robert Wahl, founder of Wahl-Henius Institute of Brewing Technology, studied pure culture yeast propagation under Emil Christian Hansen’s direct tutelage. Returning to the United States in 1886, Wahl set up a pure yeast culture system and service to provide American brewers with “pure pedigree” yeast cultures. Some of those cultures were certainly the same ones used to brew in Denmark, and they became the varieties that would eventually dominate in the United States.

Advances in the field of yeast genetics have reframed the way strains are understood and changed the way they are classified. Not long ago, Jürgen Wendland, Carlsberg’s former yeast biologist who was not involved in The Re-Brew Project, wrote that “genome sequencing of lager yeasts is only at its early beginnings.”

Nonetheless, many brewing texts are already out of date when it comes to lager yeast taxonomy. Keeping it simple, lager (Saccharomyces pastorianus) strains are currently sorted into two groups: Saaz and Frohberg. Saaz includes the Carlsberg strain (S. carlsbergensis) that Hansen first isolated. Frohberg includes Weihenstephan WS 34/70.


However, before sequencing revealed the genomic differences between these strains, chromosome fingerprinting established two basic types of fingerprints in U.S. yeast strains. Greg Casey began researching chromosome fingerprinting as a post-doctoral researcher at the Carlsberg Research Laboratory in the 1980s. Before retiring in 2013, he used the process in research while working for Anheuser-Busch, Stroh Brewery, and Coors (as well as the brewing partnerships of which Coors became a part).

His studies identified two families of industrial strains, called Carlsberg and Tuborg because the purified cultures traced back to those respective breweries. There were variations within the family, but after World War II only two large breweries in the United States were using Tuborg-type yeast—Anheuser-Busch and Coors, both of which thrived as the population of American breweries shrank.

The list of shuttered breweries that used Carlsberg yeast is familiar to those who collect Breweriana and includes Schaefer, Blatz, Falstaff, Hamms, Heileman, Lemp, Lucky Lager, Olympia, Schlitz, and many others.

Casey’s system of classification does not align perfectly with the Saaz/Froberg model, but what’s relevant is how the strains so prevalent in the United States compare. Among other things, beers fermented with Tuborg yeast attenuated better, had a higher ratio of esters to alcohol, produced a “cleaner” ester, and had less sulfur. Casey concluded that the strain was much better suited for light lagers.


Because he works on process optimization in the pilot brewery at Carlsberg, Lund knows both the Carlsberg and Tuborg strains well (Carlsberg now owns the Tuborg brand and brews the beer). “They are different but related in a number of parameters,” he says. He finds Carlsberg yeast “gives a much more crisp flavor” and the “good sort of sulfur.”

Perhaps surprisingly, August Schell Brewing in New Ulm, Minnesota, also uses both the Carlsberg-type and Tuborg-type strains. It acquired the Carlsberg-type from Schaefer Brewing and repitched it continuously for thirty-five years. That yeast sets Deer Brand, their “classic American lager” that they’ve brewed for more than 100 years, apart from Grain Belt beers, which Schell acquired in 2002 along with a Tuborg-type yeast.

The brewery does not sell Deer Brand far from New Ulm. “I’d never seen Deer Brand when I started working here,” says Head Brewer Dave Berg, a lifelong Minnesotan. “Oh wow, I love that beer. That yeast is a really strong yeast [with] a very distinct taste—very chardonnay-like with a grape component. For anything Germanic, it can be too estery.”

Grain Belt, which accounts for most of what Schell sells, ferments with a Tuborg-type strain inherited from Jacob Schmidt, which previously brewed Grain Belt. Because Schell brews Grain Belt beers so much more often than Deer Brand, the Tuborg-type strain is also the logical choice for the brewery’s all-grain beers (Deer Brand and Grain Belt are both made with a portion of corn, as they have been since before Prohibition), including beers such as Firebrick, a Vienna lager that has won multiple Great American Beer Festival and World Beer Cup medals.


Another Retro (or Is It Repro?) Beer

Urban Chestnut Brewing Company’s Forest Park Pilsner (St. Louis, Missouri) was brewed to commemorate the thirtieth anniversary of Forest Park Forever, an organization established in 1986 to restore parts of the massive park (500 acres larger than New York’s Central Park). Forest Park was established in 1876 and is most famous for hosting the 1904 World’s Fair. For the fair, the city’s brewers constructed the “World’s Fair Tyrolean Alps,” an impressive replica of the Bavarian Alps that operated as the largest dining and entertainment venue in the park.

Forest Park Pilsner has a bit of an “old” flavor, most likely because it is bittered with Cluster hops, and in many ways the recipe is faithful to one a brewer in St. Louis might have written 100 or more years ago. However, Cofounder/Brewmaster Florian Kuplent is not interested in judging whether it is authentic. “This is not meant to be a re-creation,” he says.

“I’m sure this is totally different from [what was brewed in] 1904,” says Head Brewer Jason Thompson, who wrote the recipe and might be overstating the difference. “We wanted to do something people would want to drink.”

As were most lagers at the beginning of the twentieth century, Forest Park Pilsner was brewed using 6-row barley malt and adjuncts. The two complemented each other well. Because 6-row has more enzymatic power than 2-row, it can convert the starch in adjuncts into sugar. Because the proteins in the cereals are not solubilized to a great extent during mashing, they dilute the high-soluble nitrogen content of the 6-row to produce a beer with better physical stability. This produced a beer lighter on the palate and brighter in the glass.

These days, 6-row barley is not nearly as protein-rich as it was in the early 1900s. Rather than using 30 percent or more adjuncts, which was common at the time, Thompson added 20 percent maize. The city’s most famous brewery, Anheuser-Busch, used (and still uses) rice, but many others chose corn. The cereal mash included five temperature rests. Thompson used whole-leaf hops, adding Cluster for bittering and Halltertau Tradition for aroma, targeting 30 IBUs.

And the yeast? Sometimes it’s enough to understand how your yeast works rather than to know its family history.


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