Niels Hjelte Claussen Introduces Brettanomyces to Brewing Science

On April 18, 1904, Niels Hjelte Claussen, director of the laboratory at the New Carlsberg Brewery in Copenhagen, presented a paper to the Institute of Brewing in London describing a previously unrecognized brewing yeast. Claussen had isolated the organism while studying the secondary fermentation responsible for the characteristic flavor and condition of traditional English stock beers. He proposed the name Brettanomyces, meaning “British fungus,” to reflect its association with British beer. Claussen showed that the organism could continue fermentation after ordinary brewer’s yeast had completed its work and argued that it contributed desirable character to mature English ales. Brettanomyces later became recognized as an important component of traditional Lambic and Gueuze fermentation, while also being treated as a potential spoilage organism in other beers and wines. Claussen’s work brought the yeast into brewing science and established the name by which the genus is still known.