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. WO2007102850A1: Gluten-Free Beer And Method For Making The Same

Today in 2007, US Patent WO 2007102850 A1 was issued, an invention of Russell J. Klisch, assigned to the Lakefront Brewery, for his “Gluten-Free Beer and Method For Making the Same.” Lakefront Brewery developed this patented for their beer New Grist. Here’s the Abstract:

A gluten-free beer derived from fermentable sugars obtained from an enzymatic reaction with gluten-free cereals and grains, and a method of making a gluten-free beer that includes dissolving enzyme-produced fermentable sugars derived from gluten-free cereals and grains in water to produce an aqueous solution, adding a yeast nutrient, a protein coagulant and hops to the aqueous solution to form an aqueous brew, and fermenting the aqueous brew by the addition of yeast to produce a gluten-free beer.


Patent No. 3834296A: Continuous Production Of Beer Wort From Dried Malt

Today in 1889, US Patent 3834296 A was issued, an invention of Uwe Jess and Wolfgang Kehs, for their “Continuous Production of Beer Wort From Dried Malt.” Here’s the Abstract:

An apparatus for continuously making beer wort from dried malt has a malt soaking unit and a malt crusher which is adapted to receive the soaked malt from the unit and has at least two smooth-surface cooperating rolls and drive means for driving them at differential velocities. A conduit system has a plurality of upright heatable conduit sections and serves for heating a mash which is produced after the malt has been treated in the crusher, and a clarifying unit is provided for clarifying the mash having been heated previously.


Patent No. 708942A: Apparatus For Racking Off Beer

Today in 1902, US Patent 708942 A was issued, an invention of Harry Torchiani, for his “Apparatus For Racking Off Beer.” There’s no Abstract, although in the description it includes these claims:

My invention relates to apparatus for filling barrels, kegs, or the like with fermented liquids, such as beer; and one of the objects of the invention is to collect the foam that arises in a barrel or keg being charged and prevent it from passing into another barrel or keg that is being charged; and another object of the invention is to provide improved means for firmly connecting the racking-off faucet with a barrel or keg and for readily disconnecting it therefrom; and to these ends my invention comprises the novel details of improvement that Will be more fully hereinafter set forth, and then pointed out in the claims.


Patent No. DE2808712A1: Plant To Manufacture Beer Wort By Hydrating Crushed Malt

Today in 1979, US Patent DE 2808712 A1 was issued, an invention of Simon Redl, assigned to Anton Steinecker Maschinenfabrik, for his “Plant to Manufacture Beer Wort by Hydrating Crushed Malt — Introduces Water as Unbroken Film to Avoid Aeration of Product.” Here’s the Abstract:

The installation comprises a pressure roll mill for wet crushing brewers malt into a wort mixing chamber where a hydrator introduces additional water and an agitator mixes the milled malt and water. The hydrator is designed to introduce water in the form of a continuous, film which runs down a guiding surface extending into the wort mix. The guiding surface pref. extends alongside or beneath and for the full axial length of the mill rolls. The guiding surface is a side wall of the casing which forms the chamber containing the mill rolls and the agitator. Both walls are pref. employed as guiding surfaces. Water is pref. run on to the guiding surface from an adjustable width slot at the bottom of a supply pocket. The guiding surface pref. form one edge of the slot which has a width of 0.5-5.0., (1.5-3.0) mm. The hydrator offers faster and more homogeneous mixing in of water than single exit water inspectors. Undesirable aeration of the wort is held to an absolute minimum which was not possible with spray injectors.


Patent No. 969224A: Beer Filter

Today in 1910, US Patent 969224 A was issued, an invention of Ferdinand Turek, for his beer “Filter.” There’s no Abstract, although in the description it includes these claims:

This invention relates to filters and has for its object to provide an improved filter construction.


Patent No. 3526510A: Beer Foam Adhesion

Today in 1970, US Patent 3526510 A was issued, an invention of John B. Bockelmann, Leonard Raymond and William Tirado, assigned to the F. & M. Schaefer Brewing Co. for their “Beer Foam Adhesion.” There’s no Abstract, although in the description it includes these claims:

The present invention relates to a novel method of enhancing so-called foam cling in certain beers or the like, as hereinafter more specifically set forth.

The use, as additive, of the heptyl ester or the octyl ester of para-hydroxy-benzoic acid, as such or in the form of an alkali metal salt or alkaline earth metal salt thereof, as a chemical pasteurizer for-“beer (cf. US. Pat. No. 3,232,766) has eliminated the necessity for conventional pasteurization as a means for preserving beer against undesired bacterial growth. However, the presence of the said additive in beer is bound up with a drawback in that the normal foam produced by the pouring of the beer into a glass no longer has the adhesion or cling which is generally associated with beer quality and which is produced by conventional pasteurized or draft beer.

Various agents are known for achieving good adhesion to the sides of the glass from beer containing the aforesaid additives. However, these are bound up with one disadvantage or another. Elimination of the additive agents results in a beer foam that rapidly wipes the glass clean, leaving no beer foam cling and imparting, from the standpoint of those who equate beer foam cling with good quality and good appearance, an inis a desideratum in the art of making paraban-pasteurized finished beer to provide an additive which is free from any disadvantage or undesired drawback and which imparts to the beer containing heptyl or octyl ester of para-hydroxy benzoic acid the capacity of forming, upon being poured into a glass, a normal foam of good stability and good cling (sometimes referred to as curtain formation).

A primary object of the present invention is the realization of the aforesaid desideratum. Briefly stated, this is achieved according to the present invention by the expedient of incorporating into beer which has been paraben-pasteurized an appropriate and effective amount of, as foam stabilizer and curtain former, one or more of .(a) sodium dioctyl sulfosuccinate (cf. US. Pat. No. 2,441,341); (b) sodium dihexyl sulfosuccinate;- (c) sodium diamyl sulfosuccinate; (d) disodium N-octadecyl sulfosuccinamate (cf. US. Pat. No. 2,252,401); and (e) tetrasodium N-(1,2-dicarboxyethyl)-N-octadecylsulfosuccinamate (cf. US. Pat. No. 2,438,092).


Patent No. 3977953A: Process For The Production Of Hulupones

Today in 1897, US Patent 3977953 A was issued, an invention of Hubert Frhr. Von Hirsch and Alfons Hartl, assigned to the Atlantic Research Institute, for their “Process For the Production of Hulupones.” Here’s the Abstract:

Lupulones, which form a constituent of hop resins which have hitherto been separated and discarded because of their poor solubility, are converted into a hulupone-containing beer-soluble bitter-tasting product by photo-sensitized oxidation in a liquid alkaline medium. However, the oxidation, which is effected by means of oxygen or an oxygen-containing gas in the presence of one or more sensitizing dyes and under the action of visible light, is only partial; it is discontinued when the oxygen consumption resulting from the reaction exhibits a substantial decline, or when the fall in pH occurring during the reaction substantially ceases.


Patent No. WO2008101298A1: Brewing Apparatus And Method

Today in 2008, US Patent WO 2008101298 A1 was issued, an invention of Allan K. Wallace, assigned to Coopers Brewery Limited, for his “Brewing Apparatus and Method.” Here’s the Abstract:

The specification discloses brewing apparatus and a method for testing for end of fermentation of a fermenting brew. It has been determined that, once fermentation is complete, the temperature of a brew (such as beer) shows a tendency to stratify in horizontal layers. However, the activity of fermentation disrupts the tendency of the brew to stratify. Accordingly, the brewing apparatus comprises at least two temperature sensors positioned to measure a temperature difference between the temperature at a first height of the brew and the temperature at a second height of the brew. End of fermentation is identified if the temperature difference is greater than a threshold difference.


Historic Beer Birthday: Hans Adolf Krebs

Today is the birthday of Hans Adolf Krebs (August 25, 1900-November 22, 1981). He was a German-born British physician and biochemist. He was the pioneer scientist in study of cellular respiration, a biochemical pathway in cells for production of energy. He is best known for his discoveries of two important chemical reactions in the body, namely the urea cycle and the citric acid cycle. The latter, the key sequence of metabolic reactions that produces energy in cells, often eponymously known as the “Krebs cycle,” earned him a Nobel Prize in Physiology or Medicine in 1953. And it’s the Krebs cycle that is his relation to brewing, as it’s also known as the respiratory phase, the second aerobic state of the fermentation process immediately following the lag period.


Here’s a description of the Krebs cycle from Life Fermented:

The Krebs cycle, also known as the tricarboxylic acid (TCA) cycle or the citric acid cycle, is a circular and repeating set of reactions which requires oxygen. In beer making, this would occur in the first stage of fermentation when the yeast is pitched into a well aerated wort, and carries on until all oxygen is used up.
Pyruvate (are you tired of this word yet?) is first converted to acetyl-CoA (pronounced “Co-A”) in the following reaction:

pyruvate + 2 NAD+ + CoA-SH → acetyl-CoA + CO2 + NADH, with the help of the pyruvate dehydrogenase (PDH) complex. Note that this is the first time CO2 is produced, and yet more NADH is generated.

This acetyl-CoA then enters into a cycle of reactions which nets two molecules of CO2, one GTP (guanosine triphosphate, another unit of energy equivalent to ATP), three NADH, and one FADH2 (flavin adenine dinucleotide, which functions similarly to NADH). After the cycle completes, another acetyl-CoA molecule enters and the cycle repeats itself.

But wait, this just made more NADH, and we need to regenerate NAD+ so glycolysis can continue. Both the NADH and FADH2 now donate their electrons to a process called the electron transport chain/ oxidative phosphorylation. The result is a return of NAD to the NAD+ state, and a large amount of ATP cellular energy.

Because the Krebs cycle is so efficient at producing ATP energy units, this is the yeast’s preferred pathway. But, you’ll notice a rather conspicuous absence: ethanol. This is only formed in the absence of oxygen.

NPG x88332; Sir Hans Adolf Krebs

Here’s a biography of Krebs, from the Nobel Prize website:

Sir Hans Adolf Krebs was born at Hildesheim, Germany, on August 25th, 1900. He is the son of Georg Krebs, M.D., an ear, nose, and throat surgeon of that city, and his wife Alma, née Davidson.

Krebs was educated at the Gymnasium Andreanum at Hildesheim and between the years 1918 and 1923 he studied medicine at the Universities of Göttingen, Freiburg-im-Breisgau, and Berlin. After one year at the Third Medical Clinic of the University of Berlin he took, in 1925, his M.D. degree at the University of Hamburg and then spent one year studying chemistry at Berlin. In 1926 he was appointed Assistant to Professor Otto Warburg at the Kaiser Wilhelm Institute for Biology at Berlin-Dahlem, where he remained until 1930.

In I930, he returned to hospital work, first at the Municipal Hospital at Altona under Professor L. Lichtwitz and later at the Medical Clinic of the University of Freiburg-im-Breisgau under Professor S. J. Thannhauser.

In June 1933, the National Socialist Government terminated his appointment and he went, at the invitation of Sir Frederick Gowland Hopkins, to the School of Biochemistry, Cambridge, where he held a Rockefeller Studentship until 1934, when he was appointed Demonstrator of Biochemistry in the University of Cambridge.

In 1935, he was appointed Lecturer in Pharmacology at the University of Sheffield, and in 1938 Lecturer-in-Charge of the Department of Biochemistry then newly founded there.

In 1945 this appointment was raised to that of Professor, and of Director of a Medical Research Council’s research unit established in his Department. In 1954 he was appointed Whitley Professor of Biochemistry in the University of Oxford and the Medical Research Council’s Unit for Research in Cell Metabolism was transferred to Oxford.

Professor Krebs’ researches have been mainly concerned with various aspects of intermediary metabolism. Among the subjects he has studied are the synthesis of urea in the mammalian liver, the synthesis of uric acid and purine bases in birds, the intermediary stages of the oxidation of foodstuffs, the mechanism of the active transport of electrolytes and the relations between cell respiration and the generation of adenosine polyphosphates.

Among his many publications is the remarkable survey of energy transformations in living matter, published in 1957, in collaboration with H. L. Kornberg, which discusses the complex chemical processes which provide living organisms with high-energy phosphate by way of what is known as the Krebs or citric acid cycle.

Krebs was elected a Fellow of the Royal Society of London in 1947. In 1954 the Royal Medal of the Royal Society, and in 1958 the Gold Medal of the Netherlands Society for Physics, Medical Science and Surgery were conferred upon him. He was knighted in 1958. He holds honorary degrees of the Universities of Chicago, Freiburg-im-Breisgau, Paris, Glasgow, London, Sheffield, Leicester, Berlin (Humboldt University), and Jerusalem.

He married Margaret Cicely Fieldhouse, of Wickersley, Yorkshire, in 1938. They have two sons, Paul and John, and one daughter, Helen.

And in the Microbe Wiki, on a page entitled “Saccharomyces cerevisiae use and function in alcohol production,” under a section called “Fermentation of alchohol,” the Krebs cycle is placed in its portion in the fermentation process:

Saccharomyces cerevisiae is able to perform both aerobic and anaerobic respiration. The process begins with the yeast breaking down the different forms of sugar in the wort. The types of sugars typically found in wort are the monosaccharides glucose and fructose. These sugars contain a single hexose, which is composed of 6 carbon atoms in the molecular formula C6H12O6. Disaccharides are formed when two monosaccharides join together. Typical disaccharides in the wort are galactose, sucrose, and maltose. The third type of fermentable sugar in the wort is a trisaccharide. This trisaccharide is formed when three monosccharides join together. Maltotriose is the trisaccharide commonly found in the wort and is composed of three glucose molecules. The wort does contain other sugars such as dextrins but it is not fermentable by yeast10. These dextrins contain four monosaccarides joined together. In order for the yeast to use the disaccharides and trisaccharides they first must be broken down to monosaccharides. The yeast does this by using different enzymes both inside and outside the cell. The enzyme invertase is used to break down sucrose into glucose and fructose. The invertase catalyzes the hydrolysis of the sucrose by breaking the O-C (fructose bond). The other enzyme used is maltase, which breaks down maltose and maltotriose into glucose inside the cell. The enzyme does this by catalyzing the hydrolysis of the sugars by breaking the glycosidic bond holding the glucose molecules together.

Once the sugars are broken down into monosaccharides the yeast can use them. The primary step is called glycolysis. In this process the glucose is converted to pyruvate using different enzymes in a series of chemical modifications. The electrons from glucose end up being transferred to energy carrying molecules like NAD+ to form NADH. ATP is also formed when phosphates are transferred from high-energy intermediates of glycolysis to ADP. In the presence of oxygen aerobic respiration can occur. This occurs in the mitochondria of the yeast. The energy of the pyruvate is extracted when it goes through metabolic processes like the Krebs cycle. The products of this type of metabolism are ATP, H2O, and CO2. However if there is no oxygen present and an abundance of sugars, as in the wort, the yeast undergo alcoholic fermentation. This type of metabolism yields much smaller amounts of energy when compared to aerobic respiration. However, because of the large supply of sugars from the different grains the wort is a very good environment for fermentative growth. The alcoholic fermentation begins with the two pyruvate acquired from glycolysis. These two pyruvate are decarboxylated by pyruvate decarboxylase to form two acetaldehydes and CO2. The CO2 is the gas that is observed during fermentation as bubbles that float to the top of the wort creating the kräusen or beer head, the foam that is very characteristic of a freshly poured beer. Pyruvate decarboxylase is a homotetramer meaning it contains four identical subunits. This also means that is has four active sites. The active sites are where the pyruvate reacts with the cofactors thiamine pyrophosphate (TPP) and magnesium to remove the carbon dioxide9. The final step to form alcohol is the addition of a hydrogen ion to the aldehyde to form ethanol. This hydrogen ion is from the NADH made during glycolysis and converts back to NAD+. The ethanol is originally believed to serve as an antibiotic against other microbes. This form of defense ensures that bacteria do not grow in the wort, thus ruining the beer with off flavors. However recently with the boom of craft beer different bacteria have been purposefully added to create what is known as sour beer. The sour taste comes from the waste products of the bacteria.


To learn more about the Krebs cycle check out this video from the University of Oklahoma’s Chemistry of Beer – Unit 7 – Chemical Concepts: Krebs Cycle: