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.

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.

Today in 1882, US Patent 258664 A was issued, an invention of Friedrich Meyer, for his “Process of Making Brewers Yeast.” There’s no Abstract, though it’s described this way in the application:

This invention has relation to a process for compounding brewers yeast; and it consists in forming from hops, malt, and water under certain degrees of heat a first yeast, which is afterward used in certain proportions in another step or series of steps, wherein malt, water, and hops are again employed and subjected to heat at varying temperatures to form a second yeast, which is again employed with malt, water, and hops, subjected to heat as before and tested by a saccharometer, to form a third or stock yeast, which will last from four to six months, and from which, together with malt, hops, and water, a present use yeast, which will last about one month, may be formed by compounding therewith malt, hops, and water at certain temperatures, all of which will be hereinafter fully pointed out in the body of the specification and claim.

In carrying out this process I take the proportions of about one-half ounce of hops to one-half gallon of boiling water, throw the hops into the yeast-can, and add the boiling water, and stir this mixture until the heat recedes to 190 Fahrenheit. I then add three quarts of cracked barley-malt and mash it well, after which 1 add one quart of boiling water and stir the mixture until the heat recedes to 160 Fahrenheit, when I cover the can and let the contents stand for five minutes. I then increase the heat by adding as little boiling water as possible until 176 Fahrenheit has been reached, when I again cover the can and let it stand for one hour, then cool the contents of the can by stirring them until the heat has receded to 90 Fahrenheit. I then put the liquid thus formed into a stone jar and place the jar into warm water at a temperature of about 80 or 90 Fahrenheit, and keep the heat of the Water up to that point by using boiling water until the liquid has ceased to ferment, which will be from thirty-six to forty-eight hours. As this yeast will last only from six to eight hours, the preparations for the formation of the second yeast should be completed at this time.

To make the second yeast, I take one gallon (dry measure) of cracked barley-malt and put it in the yeast can, and pour one-half gallon of boiling water thereon, and mash well together. This should be permitted to stand ten minutes, and then raised to a temperature of 176 Fahrenheit by adding boiling water to the amount of about three gallons. It should be then covered and permitted to stand for about one hour, after which it should be strained through a brass sieve into a clean tin can and placed 011 the stove, where it should boil for one hour and be skimmed during the operation of boiling. If one hours boiling should prove to be insufficient, it may be boiled a little longer. It, should register, when properly boiled, about 20 saccharometer, and the test should be made at 90 Fahrenheit. About two ounces of hops should then be added by stirring them in until the hops are thoroughly wetted, and the cover should be again replaced and the contents of the can boiled from three to five minutes longer. Remove the can from the stove and let it stand fifteen minutes, and then strain the contents of the can through a brass sieve into a stone jar, and cool it to about 94 Fahrenheit by setting the stone jar into cold water in the winter season. In summer it should be reduced to 90 Fahrenheit, as the natural temperature at this season will cause the temperature of the liquid to rise in a short time. Then add to the liquid thus produced one pint of the first yeast to each gallon of the liquid. Then wrap the jar in cloth, and set it away in a place where the temperature may be maintained at from to Fahrenheit until it is done fermenting, which’ will be about thirty-six hours. Then be ready to proceed to the formation of the third yeast, as this, which is termed the second yeast, will not keep longer than from ten to twelve hours.

To form the third yeast, I place four gallons of boiling water in the yeast-can and permit the heat to recede to 180 or 176 Fahrenheit. I then add about sixteen pounds of cracked barley-malt and mash well. The can is then rinsed down with about one-half gallon of boiling water and stirred until the temperature is about 150, and then left to stand about ten minutes. Boiling water should then be added and the contents of the can stirred until the heat reaches 176 Fahrenheit, after which it should be covered and left to stand for one hour, and should then be strained through a brass sieve. Then take this liquid and place it in a clean tin can and set it on the stove and boil it from three to five hours, skimming it during the operation of boiling, until it be comes of a consistency of 38 saccharometer under a test at 90 Fahrenheit. Then put in one-half pound of hops and stir until the hops are thoroughly wetted, and then boil from three to five minutes longer. Remove the can from the stove, stir the contents, cover the can, and let it stand covered for about fifteen minutes, during which time it should be stirred occasionally, and then strained through a brass sieve into a clean yeast-can, and reduce its temperature to 91 Fahrenheit by placing the yeast-can into cold water. Then add one quart of the second yeast above described and stir well. The temperature during this stirring should be maintained at about 00 Fahrenheit. Then wrap the can in cloth and place it in a place where the temperature may be maintained at between and Fahrenheit until fermentation ceases, which will be about forty-eight hours. This yeast, called the third yeast, will then be lit for use. This third or stock yeast will keep from four to six months, and should always be thoroughly shaken before using. This stock yeast is intended for shipment for use in making a fourth or pre-cut use yeast, which, when made as herein after described, will keep about one month.

To make the fourth or present-use yeast, I take fifteen quarts of boiling water and place it in the tin yeast-can and let it reach a temperature of 170 Fahrenheit, and then place in it about sixteen pounds of cracked barley malt, mash well, and rinse down with about one quart of boiling water and stir until the temperature is about 150 Fahrenheit, then cover the can and let it stand about ten minutes. I then add boiling water until the temperature reaches 176 Fahrenheit, which requires about sixteen quarts of boiling water. I then let it stand on the stone and boiled for about three hours to thicken it, care being taken to skim the contents during the operation of boiling. The proper consistency should be about 30 saccharometer under a test at 90 Fahrenheit. When at this consistency about six ounces of hops should be thoroughly stirred in, and the contents should be boiled from three to five minutes longer. The can should then be removed from the stove and left to stand for about fifteen minutes, during which time it should be stirred occasionally. It should then be strained through a brass sieve into a yeast-can, which should be placed in cool water, stirred, and reduced to a temperature of 90 Fahrenheit. One quart of the third or stock yeast should then be added by stirring it in under a temperature of 90 Fahrenheit, and the can wrapped up and placed in a position where a temperature of from 60 to 70 Fahrenheit can be maintained until fermentation ceases, which will be about forty-eight hours, after which it will be fit for use.

The superiority of this stock yeast over the yeast now employed lies in this, that it may be kept in stock for a period of six months, and from it a present-use yeast may be made that will last for a period of about one month, while the yeasts now employed will keep but a few hours at the furthest.