Brewing technology · Biology
Pure yeast culture
Growing a brewery’s yeast from one isolated cell, which turned fermentation from something that mostly worked into something that could be relied upon.
Before
Brewers pitched yeast saved from the previous batch. That yeast was a population — several strains of brewing yeast plus whatever wild yeast and bacteria had joined it — and it drifted. A brewery could go for years with a good house culture and then find its beer turning sour or thin for reasons nobody could name, because the reasons were invisible. "Beer sickness" was a recurring commercial catastrophe with no diagnosis and no cure beyond throwing everything out and starting again with yeast begged from a brewery that was still healthy.
After
Emil Christian Hansen, at the Carlsberg Laboratory, isolated single yeast cells and grew each into a pure population, then showed that the culprit in spoiled lager was frequently not bacteria but *other yeast*. From 1883 Carlsberg brewed with a pure culture. Consistency became achievable, brewing at very large scale became safe, and a brewery could reproduce its own beer indefinitely. Lager brewing in particular depends on it — a long cold fermentation gives contaminants a great deal of time.
The historical question this page exists to answer. How the technique itself works is on the brewing process pages linked below.
Why it spread
Spread quickly among lager brewers, and much more slowly among ale brewers — several British breweries kept mixed house cultures deliberately, because the mixture was part of the flavour rather than a defect. That divergence still exists: a Belgian mixed-fermentation brewery is not failing to adopt pure culture, it is declining to.
Who is credited
Hansen developed the isolation method and the strain entered production at Carlsberg in 1883. Carlsberg did not patent it, which is why the technique spread through the industry rather than staying with one company.
A contemporary record supports this attribution.
Styles that exist because of it
Or that changed materially. A style listed here would be a different beer, or would not be brewable at all, without this.
- German Pils
Pale, dry and firmly bitter, with a crisp finish and a spicy-floral noble hop character — Germany’s answer to the Bohemian original.
- Munich Helles
Bavaria’s everyday pale lager: soft, bready and malt-forward, with just enough hop to balance and nothing to distract.
- International pale lager
The global mainstream lager: pale, clean, lightly hopped and built for consistency and refreshment above flavour intensity.
What people get wrong
Pure culture means better beer.
It means repeatable beer. Some of the most admired beer in the world is made with deliberately mixed cultures, and the lambic breweries have never adopted this and never should. What pure culture removes is unpredictability, which is worth everything at industrial scale and is not always worth having.
Related myths
Questions
Who developed pure brewing yeast?
Emil Christian Hansen at the Carlsberg Laboratory in Copenhagen. He isolated single yeast cells, grew each into a pure population, and showed that spoiled lager was often caused by other yeasts rather than by bacteria as Pasteur had assumed. Carlsberg brewed with a pure culture from 1883 and did not patent the method, so it spread across the industry.
Connected
How it works: Pitching · Yeast harvesting · Bottom fermentation
Ingredients and packages: Saccharomyces pastorianus · Saccharomyces cerevisiae
Dated events: Pasteur establishes that fermentation is microbial · Hansen isolates a pure yeast culture at Carlsberg · The wild parent of lager yeast is identified
People: Emil Christian Hansen
In context: Brewing becomes a science
Last reviewed 2026-08-29.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Emil Christian Hansen isolated pure yeast cultures at the Carlsberg Laboratory after establishing that wort was being infected by wild yeasts, and the strain he selected entered production at Carlsberg in 1883.
Checked against the source
Source: Walther, Hesselbart & Wendland, "Genome sequence of Saccharomyces carlsbergensis, the world’s first pure culture lager yeast" (2014), introduction, history of the strain (G3 4(5), 783–793)