Historic Beer Birthday: Theodor Schwann

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.”

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.


Patent No. 3773222A: Beer Yeast Dosing Installation

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.


Patent No. 3407121A: Fermenter Yeast Cropping And Washing Device

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.


Patent No. 4409246A: Yeast Strain For Fermenting High Plato Value Worts

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.


Patent No. EP0070570B1: Yeast Strain For Use In Brewing

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.


Patent No. 4343231A: Brewing Apparatus Having Sampling Means Delivering Suspension To Fermenting Vessel

Today in 1982, US Patent 4343231 A was issued, an invention of Andre F. Devreux, assigned to the Compagnie Internationale de Participation et d’Investissement “Cipari” S.A., for his “Brewing Apparatus Having Sampling Means Delivering Suspension to Fermenting Vessel.” Here’s the Abstract:

A process for adjusting the amount of yeast introduced into a fermentative liquid comprises periodically taking a sample from a mass of suspended yeast maintained in movement in a closed circuit, subjecting the sample to fermentation by adding a nutrient element, and adjusting the supply of yeast to the liquid in accordance with the fermentative power of the treated yeast sample. The implementing plant comprises a container having a conical bottom containing yeast suspended in a liquid, a pipe connecting the bottom of the container to a fermentation tank, and a regulating or adjusting pump for supplying yeast from the container into the tank. A pipe for recycling the suspended yeast in the container is provided, as well as means for ensuring, during a predetermined time interval, the recycling of the suspension of yeast from the bottom of the container to the upper part thereof. Sampling means periodically extract a predetermined volume of the recycling yeast suspension and deliver it to a small fermenting vessel whereat the nutrient agent is supplied. Means are then provided for determining the fermentative power of the yeast sample and for adjusting the yeast supply of the fermentation tank in accordance therewith.


Beer Birthday: Chris White

Today is the 48th 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.

Chris and his brother Mike bookending Chuck, from Green Fash Brewing, Natalie Cilurzo, from Russian River Brewing, John Harris, from Full Sail Brewing, and Vinnie Cilurzo, also from Russian River, at CBC in Austin, Texas in 2007.

Chris at the new White Labs taproom during the Craft Brewers Conference a couple of years ago in San Diego.

Surly brewer Todd Haug with Chris.

Chris with Technical Sales and Marketing Coordinator Ashley Paulsworth at the NHC.

[Note: last two photos purloined from Facebook.]

Patent No. 1718910A: Process Of Manufacturing Yeast

Today in 1929, US Patent 1718910 A was issued, an invention of Lucien Lavedan, for his “Process of Manufacturing Yeast.” There’s no Abstract, although in the description it includes this summary:

The primary object of my invention is to provide a process in which carbon dioxide is employed to more effectively carry out in the most suitable and efficient manner, the’ continuous process of making yeast with continuous aeration in propagating pure yeast in a pure sugared liquid of a given density in the presence of nutritive salts and air; with the separation of the scum containing the yeast thus propagated Jfrom the main body of the liquid, and subsequent separation of the yeast cells from the associated liquid o the scum, with the addition of sufficient sugared solution to the separated liquid to bring the main sugared solution to its original density when the separated liquid is returned to it, as described in my Letters Patent- No. 1,201,062, on a continuous process with continuous aeration, granted October 10, 1916, the cold carbon dioxide acting as a suitable agent to neutralize an excess of alkalinity, and at the same time operating to reduce the temperature of the Wort.

Another object of`my invention is to provide a process to produce from a given amount of raw materials, the highest possible yield of yeast possessing an increased vitality and strength for baking, fermenting, diet and any other uses, while simultaneously decreasing the production of alcohol.

A further object of my invention is to produce yeast which will keep for a longer period of time than yeast produced by other processes and methods.

A further object of my invention is to produce yeast possessing a higher vitamin E and nutrient value, and far more suitable to be used for eating purposes as it is more adapted to conditions existing in the human stomach, more palatable and of better odor and taste, and possesses a more effective action than any other yeast produced by other processes and methods.


Patent No. 1767646A: Process For Manufacturing Yeast

Today in 1930, US Patent 1767646 A was issued, an invention of George S. Bratton, assigned to Anheuser-Busch, for his “Process For Manufacturing Yeast.” There’s no Abstract, although in the description it includes this summary:

This invention relates to the manufacture of yeast, and particularly, to processes of the kind which contemplate initiating propagation of yeast in a dilute Wort, and thereafter adding or feeding into same a highly concentrated Wort .that contains yeast nourishing materials.


Patent No. WO2001040514A1: Method Of Judging Flocculating Properties Of Bottom Brewer’s Yeast

Today in 2001, US Patent WO 2001040514 A1 was issued, an invention of Makiko Jibiki, assigned to Asahi Breweries, Ltd., for his “Method of Judging Flocculating Properties of Bottom Brewer’s Yeast.” Here’s the Abstract:

A method of easily evaluating the flocculating properties of bottom brewer’s yeast within a short period of time at a high reproducibility without carrying out fermentation. This method is characterized by using the ORF sequence of a flocculation gene FLO5 of a laboratory yeast Saccharomyces cerevisiae.