They were one of the first breweries to set up a proper laoratory and carried out much ground-breaking research. As they continue to do to this day. Whatever you migh think of their beer, their contribtions to brewing science have been immense. Especially in the field of yeast.
"The Carlsberg Brewery.— In his last report on the trade of Denmark the British Consul at Copenhagen, referring to Danish breweries, says that the same thoroughness of purpose which is so generally noticeable in all enterprises undertaken in Denmark has for many years past been brought to bear on this industry, and notably by the late Captain Jacobsen, whose brewery at Old Carlsberg is the result of a lifetime devoted to the perfecting of the various processes, and is at this day a model establishment, in which no expenditure is spared to maintain the excellence of the produce. In a well-fitted laboratory annexed to the establishment, under the superintend ence of Dr. E. C. Hansen, experiments are made, in the results of which the trade at large is allowed to participate. Dr. Hansen is a distinguished disciple of Pasteur, and independent discoveries have been made by him on the propagation of micro-organisms. These researches led him to the cultivation of pure yeast, which since 1885 has been exclusively used in the brewery. A few years ago at one of the other breweries at Old Carlsberg heavy losses had been sustained in consequence of the beer turning sour at intervals for a period of two years. Dr. Hansen ultimately traced the cause, and for the first time had an opportunity of trying on an extended scale his then recently-discovered pure yeast. The result was in every way satisfactory, and from that day his system has practically been applied at Old Carlsberg. In an interesting monograph contributed to the scientific periodical published at the brewery, Dr. Hansen describes the process. Briefly stated, his system consists in selecting a single cell of yeast, of a species which by experiment has been proved to give a certain ascertained result in fermentation, and from this cell to cultivate yeast in large quantities for the fermenting vats. The advantages of this mode of fermentation have now been fully recognised, and it is in use in all the large Dutch and many foreign breweries. The brewer using the pure yeast knows with absolute certainty that his beer will turn out of the desired taste and quality. It should be stated that the mode of fermentation in vogue is what is called “bottom" fermentation at a low temperature, on the Bavarian plan."
"The Brewers' Guardian 1889", 1889, page 155.
Learning how to generate 100% pure yeast was a big breakthrough, one from which almost the whole of the world's brewing industry has benefitted. Well, other than some eccentric UK breweries like Harveys.
Just as back in the 19th century, Carlsberg still makes the reults of its research available to everyone. As a real scientific institution should.
Hansen's laboratory has been preserved by Carlsberg. It's hard to describe the thrill I got entering the space where Hansen and Claussen performed such important work on yeast.
I'm not surprised that all the large Dutch breweries used pure yeast cultures. It probably came from Heineken that had a plant for producing pure yeast cultures in their Rotterdam brewery.