The Yeast that Conquered the World
It’s winter in Carnuntum, a Roman fortress next to the River Danube. The year is 173. Cold, swirling wind bites into exposed skin huddled behind icy stone walls. Braying pack animals almost drown out the moans of dying men. A plague is spreading through Europe and war rages beyond the gate.
And yet there is beauty.
The Emperor, Marcus Aurelius, wrote about the beauty in the mundane during that terrible campaign:
“The way loaves of bread split open on top in the oven; the ridges are just by-products of the baking, and yet pleasing, somehow: they rouse our appetite without our knowing why.
Or how ripe figs begin to burst.
And olives on the point of falling: the shadow of decay gives them a peculiar beauty.”
Today, June 1, I write this newsletter while it is 6 degrees, windy and pouring rain.
But it’s not an awful day.
There is beauty everywhere. It’s in the pale, fresh green of young leaves dancing on the wind. I can see it in the tenderness of fragrant spruce tips emerging on the ends of branches in the corner park. And I know it’s there, waiting patiently in millions of cans of macro-brew lager in liquor stores all around us.
That’s right. There is beauty there, too.
Maybe not in the flavour, but in the level of technical sophistication that allows hundreds of millions of cans of beer to taste the same whether they’re brewed in Copenhagen, Calgary, or Cape Town. And there is even more beauty in the story of how it all started.
Lager emerged from a world of laboratories, railways, and industrial ambition. It was one of the first truly modern foods: a product of science, engineering, and the late-Victorian belief that technology could improve everyday life.
There was once a time when opening a lager was like drawing straws. It might be clean and refreshing. It might be sour or spoiled. The story of how that problem was solved is one of the most important stories in brewing history.
It began 180 years ago when a young Dane boarded a train in Bavaria and embarked on a journey that would change brewing forever.
The Yeast that Conquered the World
A tin rattles in a young man's luggage as the steam train approaches the platform. The carriage comes to a screeching stop as he removes the tin, hurries out of the train, and begins running cold water over it at the station. A few minutes later he's back at his seat, the cold tin stowed safely in his hatbox.
He repeats the process at the next station. And the next. He travels by stagecoach and by ferry. The journey from Munich to Copenhagen will take days.
It's 1845 and JC Jacobsen is carrying the future of brewing in one hand.
Back in Copenhagen, the contents of his tin, Bavarian yeast, are propagated and used to brew 300 barrels of lager. They sell fast. Soon the cold, underground cellars in Copenhagen aren't big enough to store all the lager Jacobsen is producing. In 1847 he starts a new brewery on a hilltop just outside of the city and names it after his five-year old son. It's called Carlsberg (Carl's hill).
For the Jacobsens, lager is the future of beer. At age 24, Carl, like his father, sets out across Europe to study the science of brewing. It's 1866. He visits top breweries in France, Germany, Austria, England and Scotland, learning the trade. When he returns home four years later his father gives him an annex at Carlsburg brewery so that he can produce ale and porter.
Carl makes lager instead.
His father expected support. What he got was competition. Rather than supporting his father's operations, Carl becomes his direct competitor. He launches a new brand with the unapologetic name New Carlsberg.
JC Jacobsen is furious. Carl discovers a way to produce lager faster than his father and soon outsells him.
JC has his lawyers evict Carl from the annex. They tell him to change his brewery's name and use a new label.
Carl doesn't listen.
He keeps using the Carlsberg labels and the name New Carlsberg.
JC responds by founding Carlsberg Laboratory in 1875. It's part industrial process control, part public research institute. Carlsberg laboratory invites top scientists from around the world to study biology, chemistry and physiology. One of the researchers he hires is Emil Christian Hansen.
Hansen's job is to separate individual yeast strains from the mixed cultures used by breweries. These mixed cultures could produce an excellent beer one month, then an awful one the next. Spoilage was a serious concern for a big exporter like Carlsberg. If batches started to go bad many months and thousands of kilometres removed from where it was produced, there could be serious financial and reputational damage.
After years spent peering into a microscope Hansen succeeded in isolating a pure culture of lager yeast in 1883. He was the first person in the world to do it. With this discovery Carlsberg became the first brewery in the world able to ferment lager using a pure yeast culture. It gave them an enormous advantage in producing clean, consistent beer. This was a way JC could get market share back from his son.
But instead he gave it away willingly.
JC Jacobsen was concerned with more than making and selling beer. He wanted to improve society. In an age when many industrialists guarded their discoveries as trade secrets, Jacobsen believed scientific knowledge should be shared. He made the discoveries of Carlsberg Laboratory public and free, including a method which allowed scientists to accurately measure nitrogen (developed by Johan Kjeldahl) that transformed agricultural and food science (1883).
The implications were enormous.
A brewer in Copenhagen could produce beer that tasted the same week after week and year after year. At the same time, the grains being used to make it could be produced at a higher quality. The biological uncertainty that had haunted brewing for centuries could finally be controlled. Carlsberg distributed Hansen's pure yeast cultures and techniques to breweries around the world, helping to transform brewing from a craft governed partly by chance into a discipline governed by microbiology.
The timing was perfect and an entire continent of beer drinkers rejoiced.
Lager beer was spreading rapidly across Europe. Refrigeration allowed breweries to produce cold-fermented beer throughout the year rather than relying solely on winter ice. Railways connected inland breweries to distant markets. Steamships shortened journeys that had once taken weeks.
Beer was becoming global.
Export lagers emerged from this new industrial world. They were brewed stronger than everyday domestic lagers. Additional hops provided stability during long voyages. Higher alcohol content helped preserve flavour. They were beers designed not simply to be consumed locally, but to travel.
A barrel of export lager leaving Copenhagen might find its way to London, St. Petersburg, Hamburg, or beyond. By the time it reached its destination, it had crossed a continent connected by steel rails, steam engines, telegraph wires, and increasingly sophisticated science.
Export lager represented a belief that careful engineering, scientific inquiry, and industrial organization could solve problems that had challenged previous generations. The same age that built ocean liners and railway networks was also redesigning beer.
JC would rebrand his original brewery as Old Carlsberg and continue to compete with his son until they reconciled in 1886, just before his death in 1887. Carl would then unify the two breweries under the original Carlsberg name, and continue the Carlsberg Institute in his father's memory, continuing its tradition of making its findings public.
One of the laboratory's most famous contributions came in 1909, when Carlsberg chemist Søren Sørensen developed the pH scale, a tool now used throughout science, medicine, agriculture, and industry.
When we drink a Danish export lager today, we are tasting more than malt and hops. We are tasting the moment when brewing entered the modern world.
It began with a young brewer carrying Bavarian yeast across Europe in a small metal tin.
By the end of the century, the brewery he founded had helped unlock the mysteries of fermentation itself.
This isn't just a beer from industrial Copenhagen. It's a beer from a time when steam engines and horses still worked side-by-side and microbiology, refrigeration, and chemistry were quietly changing the world.