Today is the 57th birthday of Chris White. Chris founded the yeast company White Labs in 1995 and he’s also on the faculty of the Siebel Institute. He’s also a fixture at virtually every brewing industry and homebrewing conference, and was kind enough to talk to my SSU beer appreciation class about yeast. Join me in wishing Chris a very happy birthday.
[Note: last two photos purloined from Facebook.]
Today is the birthday of Emil Christian Hansen (May 8, 1842-August 27, 1909). Hansen was a “Danish botanist who revolutionized beer-making through development of new ways to culture yeast. Born poor in Ribe, Denmark, he financed his education by writing novels. Though he never reached an M.Sc., in 1876, he received a gold medal for an essay on fungi, entitled “De danske Gjødningssvampe.” In 1879, he became superintendent of the Carlsberg breweries. In 1883, he successfully developed a cultivated yeast that revolutionized beer-making around the world, because Hansen by refusing to patent his method made it freely available to other brewers. He also proved there are different species of yeast. Hansen separated two species: Saccharomyces cerevisiae, an over-yeast (floating on the surface of the fermenting beer) and Saccharomyces carlsbergensis, an under-yeast (laying on the bottom of the liquid).
Here’s his entry from Encyclopedia Britannica:
Danish botanist who revolutionized the brewing industry by his discovery of a new method of cultivating pure strains of yeast.
Hansen, who began his working life as a journeyman house painter, received a Ph.D. in 1877 from the University of Copenhagen. Two years later he was appointed head of the physiology department at the Carlsberg Laboratory in Copenhagen, where he remained until his death. His research was concerned mainly with yeasts that convert carbohydrates to alcohol, and in 1888 he published an article that described his method for obtaining pure cultures of yeast. The yeast grown from these single strains was widely adopted in the bottom-fermentation brewing industries. Further investigations led him to the discovery of a number of species of yeast. He defined the characters of the different species and devised a system of classification. After further study he devised additional methods for the culture and isolation of certain species.
Emil Hansen as a young man.
This is how Carlsberg describes Hansen’s breakthrough in 1883:
The Carlsberg Laboratory made its first major scientific breakthrough when Dr. Emil Chr. Hansen developed a method for propagating pure yeast.
Fluctuations in the beer quality were not unknown at the time, but had until then been solved by thorough cleaning of all installations after suspension of production. If a brew failed, there was no use in pasteurising it; it had to be destroyed.
In 1883, the Old Carlsberg beer got infected with the beer disease and all efforts were made to find a solution to the problem.
Dr. Emil Chr. Hansen who joined the Carlsberg Laboratory in 1878 was examining the beer, and he found that it contained wild yeast. Through his studies and analyses, he discovered that only a few types of yeast (the pure yeast) are suitable for brewing, and he developed a technique to separate the pure yeast from the wild yeast cells. The problem had been solved, and the new Carlsberg yeast – Saccharomyces Carlsbergensis – was applied in the brewing process.
The propagating method revolutionised the brewing industry. Rather than to patent the process, Carlsberg published it with a detailed explanation so that anyone could build propagation equipment and use the method. Samples of the yeast – Saccharomyces Carlsbergensis – were sent to breweries around the world by request and young brewers came to Carlsberg to learn the skills.
This is the entry from Wikipedia on the history of Saccharomyces Carlsbergensis:
So-called bottom fermenting strains of brewing yeast were described as early as the 14th century in Nuremberg and have remained an indispensable part of both Franconian and Bavarian brewing culture in southern Germany through modern times. During the explosion of scientific mycological studies in the 19th century, the yeast responsible for producing these so-called “bottom fermentations” was finally given a taxonomical classification, Saccharomyces pastorianus, by the German Max Reess in 1870.
In 1883 the Dane Emil Hansen published the findings of his research at the Carlsberg brewery in Copenhagen and described the isolation of a favourable pure yeast culture that he labeled “Unterhefe Nr. I” (bottom-fermenting yeast no. 1), a culture that he identified as identical to the sample originally donated to Carlsberg in 1845 by the Spaten Brewery of Munich. This yeast soon went into industrial production in Copenhagen in 1884 as Carlberg yeast no. 1.
In 1904 Hansen published an important body of work where he reclassified the separate yeasts he worked with in terms of species, rather than as races or strains of the same species as he had previously done. Here Hansen classified a separate species of yeast isolated from the Carlsberg brewery as S. pastorianus, a name derived from and attributed to Reess 1870. This strain was admitted to the Centraalbureau voor Schimmelcultures (CBS) in 1935 as strain CBS 1538, Saccharomyces pastorianus Reess ex Hansen 1904. In a further publication in 1908, Hansen reclassified the original “Unterhefe Nr. I” as the new species Saccharomyces carlsbergensis and another yeast “Unterhefe Nr. II” as the new species Saccharomyces monacensis. The taxonomy was attributed to Hansen 1908 and the yeasts entered into the Centraalbureau voor Schimmelcultures in 1947 as CBS 1513 and CBS 1503 respectively.
Since the early 1900s, bottom-fermenting strains of brewery yeast have been typically classified as S. carlbergensis in scientific literature, and the earlier valid name assigned to a bottom-fermenting yeast by Reess in 1870 was rejected without merit. This situation was rectified using DNA-DNA reallocation techniques in 1985 when Vaughan-Martini & Kurtzman returned the species name to S. pastorianus under the type strain CBS 1538 and relegated the two former species assigned by Hansen in 1908, S. carlsbergensis CBS 1513 and S. monacensis CBS 1503, to the status of synonyms. These experiments also clearly revealed the hybrid nature of the lager brewing yeast species for the first time, even though one of the parental species was incorrectly classified in retrospect. Nonetheless, over the last decades of the 20th century, debate continued in scientific literature regarding the correct taxon, with authors using both names interchangeably to describe lager yeast.
Although most accounts mention that he wrote novels to put himself through school, one has a slightly different take, though I’m not sure how true it is. “Emil earned his bread and butter as a painter but he yearned for another life and left Ribe so he could study. He graduated from High School relatively late – he was 29 years old.”
Emil Christian Hansen, taken in 1908, a year before his death.
Today is the birthday of Louis Pasteur (December 27, 1822–September 28, 1895). He “was a French chemist and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases, and his discoveries have saved countless lives ever since. He reduced mortality from puerperal fever, and created the first vaccines for rabies and anthrax. His medical discoveries provided direct support for the germ theory of disease and its application in clinical medicine. He is best known to the general public for his invention of the technique of treating milk and wine to stop bacterial contamination, a process now called pasteurization. He is regarded as one of the three main founders of bacteriology, together with Ferdinand Cohn and Robert Koch, and is popularly known as the ‘father of microbiology.'”
But, of course, for the brewing industry, he’s best remembered for his “Studies on Fermentation,” which he published in 1876.
In 1876, Louis Pasteur published his ground-breaking volume, Études sur la Bière, soon translated into English as Studies On Fermentation. The book changed the course of brewing during the late 19th and early 20th centuries, representing a huge leap forward in the scientific understanding of the processes involved in beermaking. Brewers around the globe put Pasteur’s findings to work in their breweries, and thus plunged the industry headlong into the modern era.
In tribute to Pasteur’s tremendous contributions to brewing science, BeerBooks.com has reprinted Studies On Fermentation exactly as it appeared when first released in English, complete with all of Pasteur’s illustrations. An original 1879 edition was digitally scanned, professionally enhanced and reproduced in a hard cover format.
In his preface, Pasteur modestly wrote, “I need not hazard any prediction concerning the advantages likely to accrue to the brewing industry from the adoption of such a process of brewing as my study of the subject has enabled me to devise, and from an application of the novel facts upon which this process is founded. Time is the best appraiser of scientific work, and I am not unaware that an industrial discovery rarely produces all its fruits in the hands of its first inventor.”
But, of course, the brewing industry recognized almost immediately the impact that Pasteur’s work would have on the art and science of beermaking. Frank Faulkner, the British brewing scholar who performed the English translation, wrote, “Seeing the vast importance of Pasteur’s work from a practical point of view, after writing a review of it for the Brewers’ Journal, I determined to procure, at any rate for the use of my own pupils, a literal translation, illustrated by photo-lithographic copies of the original plates…It was on the completion of this translation that my views and desires expanded. The more I studied the work, the more I was convinced of its immense value to the brewer as affording him an intelligent knowledge of the processes and materials with which he deals…I determined accordingly to publish the work if I could secure the consent of its distinguished author…The debt which we English brewers owe to M[r]. Pasteur can hardly be over-estimated.”
While I’m sure there are probably many more, he had patents I highlighted last year, Patent No. 135245A: Improvement in Brewing Beer and Ale from 1873, and Patent No. 141072A: Manufacture of Beer and Yeast, in the same year.
A portrait of Louis Pasteur painted by Swedish-speaking Finnish artist Albert Edelfelt, in 1886.
Fermentation and germ theory of diseases
Pasteur demonstrated that fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is due not to spontaneous generation, but rather to biogenesis (Omne vivum ex vivo “all life from life”). He was motivated to investigate the matter while working at Lille. In 1856 a local wine manufacturer, M. Bigot, the father of his student, sought for his advice on the problems of making beetroot alcohol and souring after long storage. In 1857 he developed his ideas stating that: “I intend to establish that, just as there is an alcoholic ferment, the yeast of beer, which is found everywhere that sugar is decomposed into alcohol and carbonic acid, so also there is a particular ferment, a lactic yeast, always present when sugar becomes lactic acid.” According to his son-in-law, Pasteur presented his experiment on sour milk titled “Latate Fermentation” in August 1857 before the Société des Sciences de Lille. (But according to a memoire subsequently published, it was dated November 30, 1857). It was published in full form in 1858. He demonstrated that yeast was responsible for fermentation to produce alcohol from sugar, and that air (oxygen) was not required. He also demonstrated that fermentation could also produce lactic acid (due to bacterial contamination), which makes wines sour. This is regarded as the foundation of Pasteur’s fermentation experiment and disprove of spontaneous generation of life.
Pasteur’s research also showed that the growth of micro-organisms was responsible for spoiling beverages, such as beer, wine and milk. With this established, he invented a process in which liquids such as milk were heated to a temperature between 60 and 100 °C. This killed most bacteria and moulds already present within them. Pasteur and Claude Bernard completed the first test on April 20, 1862. Pasteur patented the process, to fight the “diseases” of wine, in 1865. The method became known as pasteurization, and was soon applied to beer and milk.
Beverage contamination led Pasteur to the idea that micro-organisms infecting animals and humans cause disease. He proposed preventing the entry of micro-organisms into the human body, leading Joseph Lister to develop antiseptic methods in surgery. Lister’s work in turn inspired Joseph Lawrence to develop his own alcohol-based antiseptic, which he named in tribute Listerine.
This is an ad is for Whitbread, from 1937, showing an illustration of Louis Pasteur working on his fermentation studies in a laboratory at Whitbread Brewing in 1871, nine years after he completed his first test of pasteurization, which took place April 20, 1862.
On his Wikipedia page, under the heading “Controversies, there’s this paragraph about his research into fermentation:
When Pasteur published his theory and experiments on fermentation in 1858, it was not new to science, neither the idea nor the experiment. In 1840 a German chemist Justus von Liebig had noted that yeast could induce fermentation in water. However, he did not know that yeasts were organisms. In 1856 another German, Friedrich Wilhelm Lüdersdorff, reported that yeasts were microorganisms that convert sugar into alcohol. In 1855, Antoine Béchamp, Professor of Chemistry at the University of Montpellier, showed that sugar was converted to sucrose and fructose in a closed bottle containing water and when he added calcium or zinc chloride to it, no reaction occurred. He also noticed moulds developing in the solution, but could not fathom the significance of it. He concluded that water was the factor for fermentation. He changed his conclusion in 1858 that water was not the main factor, in fact, fermentation was directly related to the growth of moulds, and moulds required air for growth. He regarded himself as the first to show the role of microorganisms in fermentation. Pasteur started his experiments only in 1857 and published his findings in 1858 (April issue of Comptes Rendus Chimie, Béchamp’s paper appeared in January issue), which, as Béchamp noted, did not bring any novel idea or experiments that earlier works had not shown. On the other hand, Béchamp was probably aware of Pasteur’s 1857 preliminary works. With both scientists claiming priority on the discovery, a bitter and protracted dispute lasted throughout their lives. Their rivalry extended to ideas on microbiology, pathogenesis, and germ theory. Particularly on the spontaneous generation because Pasteur in his 1858 paper explicitly stated that the lactic acid bacteria (he named them “lactic yeasts”), which caused wine souring, “takes birth spontaneously, as easily as beer yeast every time that the conditions are favourable.” This statement directly implied that Pasteur did believe in spontaneous generation. He condemned the ideas of Pasteur as “‘the greatest scientific silliness of the age”. However, Béchamp was on the losing side, as the BMJ obituary remarked: His name was associated with bygone controversies as to priority which it would be unprofitable to recall. Pasteur and Béchamp believed that fermentation was exclusively cellular activity, that is, it was only due to living cells. But later extraction of enzymes such as invertase by Marcellin Berthelot in 1860 showed that it was simply an enzymatic reaction.
Pasteur’s ground-breaking “Studies on Fermentation” is in the public domain, of course, so you can read the entire work, or just browse through it, at the Internet Archive.
In 1951, the United States Brewers Foundation featured Louis Pasteur in an ad, which was part of a series that used a Q&A format aimed at highlighting different positive aspects of beer and the brewing industry.
Today is the birthday of Theodor Schwann (December 7, 1810–January 11, 1882). He “was a German physiologist. His many contributions to biology include the development of cell theory, the discovery of Schwann cells in the peripheral nervous system, the discovery and study of pepsin, the discovery of the organic nature of yeast, and the invention of the term metabolism.”
So Schwann appears to have made several important contributions to science, but his most important one, for my purposes, is that his discovery of the organic nature of yeast influenced Pasteur.
Schwann was the first of Johannes Peter Müller’s pupils to break with vitalism and work towards a physico-chemical explanation of life. Schwann also examined the question of spontaneous generation, which led to its eventual disconfirmation. In the early 1840s, Schwann went beyond others who had noted simply the multiplication of yeast during alcoholic fermentation, as Schwann assigned the yeast the role of primary causal factor, and then went further and claimed it was alive. Embattled controversy ensued as eminent chemists alleged that Schwann was undoing scientific progress by reverting to vitalism.
After publishing anonymous mockery in a journal of their own editorship, they published a purely physicochemical if also hypothetical explanation of the interaction resulting in fermentation. As both the rival perspectives were hypothetical, and there was not even an empirical definition of ‘life’ to hold as a reference frame, the controversy—as well as interest itself—fell into obscurity unresolved. Pasteur began fermentation researches in 1857 by approximately just repeating and confirming Schwann’s, yet Pasteur accepted that yeast were alive, thus dissolving the controversy over their living status, and then Pasteur took fermentation researches further.
In retrospect, the germ theory of Pasteur, as well as its antiseptic applications by Lister, can be traced to Schwann’s influence.
In his biography on Famous Scientists, under the section entitled “Microbes, Yeast and Fermentation” it discusses his influence on Pasteur’s work on yeast in fermentation:
Schwann identified the role that microorganisms played in alcohol fermentation and putrefaction. He carried out a variety of fermentation experiments and by 1836 had gathered enough evidence to convince himself that the conversion of sugar to alcohol during fermentation was a biological process that required the action of a living substance (yeast) rather than a chemical process of sugar oxidation.
Unfortunately, Schwann’s explanation of fermentation was ridiculed by other scientists. Acceptance only came with Louis Pasteur’s work over a decade later. Pasteur later wrote in a letter to Schwann:
“For twenty years past I have been travelling along some of the paths opened up by you.”
LOUIS PASTEUR
Letter to Schwann, 1878
In a deeper dive about the history of yeast on Think Write Publish, entitled “For the Love of Yeast: A little cell at the cutting edge of big science,” by Molly Bain and Niki Vermeulen, in Chapter 2, they discuss Schwann, Pasteur and others unlocking the secrets of yeast’s role in fermentation:
People had been using yeast—spooning off its loamy, foamy scum from one bread bowl or wine vat and inserting it in another—for thousands of years before they understood what this seething substance was or what, exactly, it was doing. Hieroglyphs from ancient Egypt already suggested yeast as an essential sidekick for the baker and brewer, but they didn’t delineate its magic—that people had identified and isolated yeast to make bread rise and grape juice spirited was magic enough. As the great anatomist and evolutionary theory advocate Thomas Henry Huxley declared in an 1871 lecture, “It is highly creditable to the ingenuity of our ancestors that the peculiar property of fermented liquids, in virtue of which they ‘make glad the heart of man,’ seems to have been known in the remotest periods of which we have any record.”
All the different linguistic iterations of yeast—gäscht, gischt, gest, gist, yst, barm, beorm, bären, hefe—refer to the same descriptive action and event: to raise, to rise, to bear up with, as Huxley put it, “‘yeasty’ waves and ‘gusty’ breezes.” This predictable, if chaotic and muddy, pulpy process—fermentation—was also known to purify the original grain down to its liquid essence—its “spirit”—which, as Huxley described it, “possesses a very wonderful influence on the nervous system; so that in small doses it exhilarates, while in larger it stupefies.”
Though beer and wine were staples of everyday living for thousands and thousands of years, wine- and beer-making were tough trades—precisely because what the gift of yeast was, exactly, was not clear. Until about 150 years ago, mass spoilage of both commercial and homemade alcoholic consumables was incredibly common. Imagine your livelihood or daily gratification dependent on your own handcrafted concoctions. Now, imagine stumbling down to your cellar on a damp night to fetch a nip or a barrel for yourself, your neighbors, or the local tavern. Instead you’re assaulted by a putrid smell wafting from half of your wooden drums. You ladle into one of your casks and discover an intensely sour or sulfurous brew. In the meantime, some drink has sloshed onto your floor, and the broth’s so rancid, it’s slick with its own nasty turn. What caused this quick slippage into spoilage? This question enticed many an early scientist to the lab bench—in part because funding was at the ready.
In a 2003 article on yeast research in the journal Microbiology, James A. Barnett explains that because fermentation was so important to daily life and whole economies, scientific investigations of yeast began in the seventeenth century and were formalized in the eighteenth century, by chemists—not “natural historians” (as early biologists were called)—who were originally interested in the fermentation process as a series of chemical reactions.
In late eighteenth-century Florence, Giovanni Valentino Fabbroni was part of the first wave of yeast research. Fabbroni—a true Renaissance man who dabbled in politics and electro-chemistry, wrote tomes on farming practices, and helped Italy adapt the metric system—determined that in order for fermentation to begin, yeast must be present. But he also concluded his work by doing something remarkable: Fabbroni categorized yeast as a “vegeto-animal”—something akin to a living organism—responsible for the fermentation process.
Two years later, in 1789 and in France, Antoine Lavoisier focused on fermentation in winemaking, again regarding it as a chemical process. As Barnett explains, “he seem[ed] to be the first person to describe a chemical reaction by means of an equation, writing ‘grape must = carbonic acid + alcohol.’” Lavoisier, who was born into the aristocracy, became a lawyer while pursuing everything from botany to meteorology on the side. At twenty-six, he was elected to the Academy of Sciences, bought part of a law firm specializing in tax collection for the state, and, while working on his own theory of combustion, eventually came to be considered France’s “father of modern chemistry.” The French government, then the world’s top supplier of wine (today, it ranks second, after Italy), needed Lavoisier’s discoveries—and badly, too: France had to stem the literal and figurative spoiling of its top-grossing industry. But as the revolution took hold, Lavoisier’s fame and wealth implicated him as a soldier of the regime. Arrested for his role as a tax collector, Lavoisier was tried and convicted as a traitor and decapitated in 1794. The Italian mathematician and astronomer Joseph-Louis Lagrange publicly mourned: “It took them only an instant to cut off his head, and one hundred years might not suffice to reproduce its like.”
Indeed, Lagrange was onto something: the new government’s leaders were very quickly in want of scientific help for the wine and spirits industries. In 1803, the Institut de France offered up a medal of pure gold for any scientist who could specify the key agent in the fermenting process. Another thirty years passed before the scientific community had much of a clue—and its discovery tore the community apart.
By the 1830s, with the help of new microscope magnification, Friedrich Kützing and Theodor Schwann, both Germans, and Charles Cagniard-Latour, a Frenchman, independently concluded that yeast was responsible for fermenting grains. And much more than that: these yeasts, the scientists nervously hemmed, um, they seemed to be alive.
Cagniard-Latour focused on the shapes of both beer and wine yeasts, describing their cellular bulbous contours as less like chemical substances and more resembling organisms in the vegetable kingdom. Schwann pushed the categorization even further: upon persistent and continued microscopic investigations, he declared that yeast looks like, acts like, and clearly is a member of the fungi family—“without doubt a plant.” He also argued that a yeast’s cell was essentially its body—meaning that each yeast cell was a complete organism, somewhat independent of the other yeast organisms. Kützing, a pharmacist’s assistant with limited formal training, published extensive illustrations of yeast and speculated that different types of yeast fermented differently; his speculation was confirmed three decades later. From their individual lab perches, each of the three scientists concluded the same thing: yeast is not only alive, but it also eats the sugars of grains or grapes, and this digestion, which creates acid and alcohol in the process, is, in effect, fermentation.
This abrupt reframing of fermentation as a feat of biology caused a stir. Some chemist giants in the field, like Justus von Liebig, found it flat out ridiculous. A preeminent chemistry teacher and theorist, von Liebig proclaimed that if yeast was alive, the growth and integrity of all science was at grave risk: “When we examine strictly the arguments by which this vitalist theory of fermentation is supported and defended, we feel ourselves carried back to the infancy of science.” Von Liebig went so far as to co-publish anonymously (with another famous and similarly offended chemist, Friedrich Wöhler) a satirical journal paper in which yeasts were depicted as little animals feasting on sugar and pissing and shitting carbonic acid and alcohol.
Though he himself did little experimental research on yeast and fermentation, von Liebig insisted that the yeasts were just the result of a chemical process. Chemical reactions could perhaps produce yeast, he allowed, but the yeasts themselves could never be alive, nor active, nor the agents of change.
Von Liebig stuck to this story even after Louis Pasteur, another famous chemist, took up yeast study and eventually became the world’s first famous microbiologist because of it.These long-term investigations into and disciplinary disputes about the nature of yeast reordered the scientific landscape: the borders between chemistry and biology shifted, giving way to a new field: microbiology—the study of the smallest forms of life.
While searching for something else this morning, I came across some word nerdery about the word “yeast.” In “Sharpe’s Diamond dictionary of the English Language,” by John Sharpe, John Thompson, and William Harvey, which was published in 1841, they list the following:
Yest, or Yeast, s. the froth in the working of ale or beer
Yest’y, Yea’sty, a. frothy; smeared with yest
I confess to not often paging though old brewing books the way I imagine Martyn and Ron do, so I had not seen this spelling before.
Merrian-Webster states simply that “yest” is an “archaic variant of yeast.” And Webster’s 1913 Dictionary just refers you to Yeast: “n. 1. See Yeast.” And my 1971 O.E.D. states that it’s an obselete form of yeast.
That same O.E.D. gives a number of different forms of the word yeat, most of which I was unfamiliar with.
Forms 1. zist, zyst, 3. zest(e, zeest, yeest 6-9 yest, 7 eyst (?) 8-9 dial. east, dial. yist, 7- yeast.
From what I can tell, the first evidence of “yest” in print is from 1530: “Yest or barme for ale” whereas our modern spelling, “yeast” doesn’t show up until 1600.
Monday’s ad is for Schlitz, from 1906. In the first decade of the 20th century, Schlitz Brewing, then one of the largest breweries in the U.S. after the industry had shrunk from over 4,000 to around 1,500 in just 25 or so years, did a series of primarily text ads, with various themes. In this ad, Schlitz claims their yeast is “a secret” and that it’s responsible, at least in part, for its “peculiar goodness.” I’m not sure I’d want to describe my beer as “peculiar,” not matter good its peculiarity.
Today in 1973, US Patent 3773222 A was issued, an invention of Erich Fiebinger, assigned to Draft Systems, Inc., for his beer yeast “Dosing Installation.” Here’s the Abstract:
A dosing system for continuously dosing and dispensing the respective quantities of auxiliary filtering substances to be added in connection with a settling filtration to a cloudy liquid, especially beer, for the cooling and yeast sediments, according to which for dispensing an auxiliary filtering substance for the cooling sediments as well as an auxiliary filtering for the yeast sediment there is provided one dosing device each equipped with a flow meter while both devices which are directly connected to the cloudy liquid conveying conduit are preceded by a flow meter and a device for measuring the total cloudiness of the liquid and by a measuring device provided with a heating zone for measuring the yeast sediment in the cloudy liquid conveying conduit. The dosing installation includes a control device for controlling the dosing devices in conformity with the cloudiness measured by the respective devices.
Today in 1968, US Patent 3407121 A was issued, an invention of Gerald Einar Wilson and Louis A. Le Seelleur, assigned to John Labatt Breweries, for their “Fermenter Yeast Cropping and Washing Device.” There’s no Abstract, although in the description it includes these claims:
A fermenter vessel containing a yeast cropping and cleaning device consisting of a rotatable header pipe in the upper portion of the vessel with an end of the pipe extending outside the vessel and a series of orifices opening from the header into the vessel. The orifice outlets are offset a substantial distance radially from the axis of rotation of the header pipe either by providing an offset portion in the header pipe itself or by providing a series of branch pipes extending laterally from the header pipe with nozzles on the outer ends thereof. Conduit means connected to the external end of said header pipe by means of a connector and suction means associated with said conduit for cropping the yeast.
This invention relates to a yeast cropping and washing device for closed fermenting vessels used in the brewing industry.
The fermentation of wort is one of the most important steps in the brewing process. Brewers yeast, having the ability to assimilate simple nitrogenous compounds and reproduce and break down sugars to carbon dioxide and alcohol are introduced into the wort, whereupon through a controlled biological fermentation process, the wort is transformed into beer. The fermentation of wort is usually an operation carried out under relatively low pressure (1-3 p.s.i.g.) in large metal fermenting vessels capable of holding thousands of gallons of wort. The modern fermenting vessel is a closed vessel such as that described in applicants co-pending application entitled, Multipurpose Process Vessel for Heat Transfer Operations.
During the fermentation, top fermenting yeast forms on the surface of the liquid in the vessel and this is normally removed by skimming or is allowed to work over the rim of a tank into chutes or troughs. In the closed vessel it is, of course, necessary to use some form of yeast cropping device and according to the present invention a new device has been developed which can be used both for cropping yeast from the surface of the beer in the fermenter and for cleaning the fermenter after the beer has been removed.
The cropping and cleaning device according to this invention consists of a horizontally extending pipe which is rotatable within the fermenter and the rotatable pipe has a series of orifices which are adapted to draw off yeast from the fermenter or to spray cleaning solution into the fermenter. The pipe is arranged such that by rotating it the elevation of the orifices can be varied to permit the yeast to be drawn off to the desired level. One end of the rotatable pipe has a fluid connection to an external pipe through a connector which permits relative rotation between the two pipes while fluid is passing through. Suitable valve means are provided so that cleaning solution can be forced into the vessel or yeast can be drawn out of the vessel through the connector and rotatable pipe.
Today in 1983, US Patent 4409246 A was issued, an invention of Graham G. Stewart, Thomas E. Goring, and Ingeborg Russell, assigned to the Labatt Brewing Company, for their “Yeast Strain For Fermenting High Plato Value Worts.” Here’s the Abstract:
The specification discloses a novel brewers’ yeast strain and a method of manufacturing the same. The yeast is a strain of Saccharomyces cerevisiae and has been deposited at the National Collection of Yeast Cultures, Norwich, England under the number 962. Morphologically the giant colony of the novel strain can be described as a circular colony having a slightly serrated periphery, a convex surface topography with a central, globular dome and exhibiting primary concentric convolutions and secondary radial convolutions which, in combination, impart a rough appearance to the surface. The novel ale strain has the advantages that it is effective in worts having high plato values and is a bottom-cropping strain.
Today in 1989, US Patent EP 0070570 B1 was issued, an invention of George Stewart Graham, Edmund Goring Thomas and Russell Ingeborg, assigned to the Labatt Brewing Company, for their “Yeast Strain For Use in Brewing.” There’s no Abstract, although in the description it includes these claims:
This invention relates to a novel yeast strain suitable for use in the brewing of beer and to a method of preparing the same.
In the brewing of beer, i.e. ale and lager, ale yeast strains (Saccharomyces cerevisiae) are traditionally top-cropping strains and lager yeast strains (Saccharomyces uvarum (carlsbergensis)) are bottom-cropping strains. That is, when the attenuation of the wort, which may be broadly defined as the conversion of fermentable substrate to alcohol, has attained a certain level, the discrete yeast cells of most ale strains adhere or aggregate to an extent that, adsorbed to bubbles of carbon dioxide, they will rise to the surface under quiescent conditions (e.g. when the medium is not agitated) where they are “cropped” by being skimmed off. In the case of lager strains, the aggregated cells are not adsorbed to bubbles of carbon dioxide and settle out of suspension to the bottom of the vessel where they are “cropped” by various standard methods.
One of the limitations of the known ale yeast strains is that they do not function satisfactorily in worts having plato values (°P) higher than about 14.5°P and values of only about 9°P to 12°P are usually required. The plato value (°P) is defined as the weight of dissolved solids, expressed as a percentage, in water at 15.6°C. Generally, the higher the plato value at which a yeast strain will function, the greater is the conversion of fermentable substrate to alcohol for a given volume of wort. Consequently, the resultant fermentation product would be one of higher than usually desired final alcohol content and would generally be diluted before packaging. Since the dilution to obtain a standard, commercially acceptable product would occur at the end of the brewing process, the overall throughput of such a brewing system would be substantially increased over a conventional system. Furthermore, beers produced from such high plato worts generally exhibit improved colloidal haze and flavour stability.
In view of the economic advantages possible in fermenting worts of higher plato values, there has been a substantial amount of research carried out in the hope of obtaining a yeast strain which will function at such higher plato values in the range of about 16°P to 18°P, i.e. a yeast strain which will remain in the body of the wort until substantial or total conversion of the fermentable sugars to alcohol atthe higher Plato values has occurred. As an alternative, attempts have been made to maintain known yeast strains in the body of the wort by mechanical means, such as continuous stirring, in the hope thatthe yeast would continue to function if maintained in contact with the wort. However, this has proved to be inefficient and in many cases more expensive because of the extra energy required to operate such mechanical means. Furthermore, many such attempts have been frustrated by difficulties of product flavour match with present commercially acceptable standards.
The inventors of this invention have now discovered a yeast strain which is an ale yeast (species Saccharomyces cerevisiae) that not only functions at high plato values, e.g. up to about 18°P, but also flocculates to the bottom of the fermenting vessel when conversion or attenuation has been substantially completed (the latter feature, as noted above, is usually characteristic of a lager strain rather than an ale strain).
The present novel organism was found to be a component of a mixture of ale yeasts maintained by the assignee. The organism was isolated and biologically pure cultures thereof were produced by techniques considered standard by those skilled in the art and can be obtained upon request from the permanent collection of the National Collection of Yeast Cultures (termed “NCYC” herein), Food Research Institute, Norwich, Norfolk, England. The accession number of the organism in this repository is NCYC No. 962.
Thus, according to one aspect of the present invention there is provided a brewing process wherein a malt wort is prepared; fermented with brewers’ yeast; and, following completion of the fermentation, finished to the desired alcoholic brewery beverage; the improvement comprising fermenting said wort having a Plato value of about 14.5 or greater with a strain of the species Saccharomyces cerevisiae brewers’ yeast having the NCYC No. 962.
In another aspect the invention provides a brewing process for producing ale, wherein a hopped, 30% corn grit adjunct wort is prepared having a Plato value of from about 16°P to 18°P; fermented at a temperature of about 21°C for about 3 to 5 days with a species of Saccharomyces cerevisiae brewers’ yeast; and, following completion of the fermentation, finished to the desired ale; the improvement comprising fermenting said wort with a strain of the species Saccharomyces cerevisiae brewers’ yeast having the NCYC No. 962.
In a further aspect the invention provides a biologically pure culture of a brewers’ yeast strain of the species Saccharomyces cerevisiae having the NCYC No. 962, said strain having the ability to ferment high Plato value worts of 14.5 or greater and the ability of flocculate to the bottom of the fermentation vessel when attenuation is substantially complete.
In a further aspect of the invention provides a method of manufacturing a novel brewers’ yeast strain, wherein a yeast strain is propagated in an oxygenated nutrient medium, the improvement comprising propagating a biologically pure culture of a yeast strain of the species Saccharomyces cerevisiae having the NCYC No. 962.
The advantage of the yeast strain of the present invention (referred to herein as strain 962 for the sake of convenience) is that it has both bottom-cropping characteristics as well as the ability to ferment high specific gravity worts. The bottom-cropping characteristic is advantageous because of increased utilization in the brewing industry of large conical-based vessels for fermenting the wort, and bottom-cropping is especially facile in such vessels. Thus strain 962 is particularly well adapted for use with continuous brewing techniques as well as batch-wise brewing.
The fact that strain 962 can ferment worts having high plato values is economically advantageous in that use of such worts allows dilution with water at a much later stage in the processing, generally prior to packaging. By reducing the amount of water required in the majority of process stages, increasing production demands can be met without the expansion of existing brewing, fermenting and storage facilities and the overall throughput of an existing brewery system can be substantially increased by the use of strain 962. Consequently, the brewing process can be carried out at a reduced overall cost, including a reduced energy cost.
Thus, while a number of bottom-cropping ale strains are known, the dual characteristics of bottom-cropping and the ability to ferment which gravity worts makes strain 962 of the present invention especially useful in the brewing of ale.
