Today in 1964, US Patent 3145106 A was issued, an invention of George F. Goerl, for his “Addition Of Dry Clay To Beer.” There’s no Abstract, although in the description it includes these claims:

The gist of the present invention lies in the addition of chill-proofing clay to beer in dry form without first forming an aqueous slurry of the clay as in prior procedures. The dry clay is introduced into the beer by incorporating the clay in the conventional filter cake used to pre-filter beer after fermentation. The clay enters the beer as the beer passes through the filter cake. By adding the clay in dry form the sludge and beer loss attendant the use of hydrated clay is avoided. In addition, the chill-proofing effect of the clay appears to be enhanced by the present method.

Thus in the preferred embodiment there is provided an improved method for adding clay to beer in order to chill-proof the beer comprising slurrying diatomaceous earth and hectorite in a preselected volume of beer, forming an initial filter cake from said slurry of diatomaceous earth and hectorite, and flowing beer after fermentation through said filter cake to pre-filter the beer and to erode hectorite from the filter cake into the beer to chill-proof the beer. A beer slurry of diatomaceous earth and hectorite is continuously added in controlled quantities to beer prior to passage of the beer through the filter cake in order to continuously build up the filter cake and replace eroded hectorite. The initial cake and continuous addition are controlled to provide about 200 p.p.m. of hectorite with respect to the beer for erosion into the beer.

The present invention applies to malt beverages generally including beer, ale, stout, and the like. For ease of description, beer has been frequently used throughout the specification and claims. However, wherever the term beer appears it should be understood that the other related malt beverages could be readily substituted therefor.

Beer production follows a generally accepted sequence of steps. First, aqueous extract from suitable grain is fermented to produce beer. After fermentation has been completed, the temperature is dropped to approximately 30 F. and the beer is transferred from the fermentation equipment into a storage tank for a rest or aging period at about 30-32 F. The rest period may be as little as five days and in some cases as much as three months. Carbon dioxide may or may not be introduced into the beer during the rest period. The carbon dioxide is used to partially carbonate the beverage and purge the liquid of entrapped air.

After this first storage the beer is put through a preclarification or prefiltration operation. This is usually accomplished with some mechanical means such as a centrifuge or a filter. The present invention comes into play in this preclarification step. Most prevalently, the preclarification or first filtration (a second or polish filtration occurs at the termination of the processing of the beer) is accomplished by passing the beer through a filter cake formed by any suitable porous filtering substance. Most preferably and commonly, the substance employed is diatomaceous earth. However, other suitable substances such as perlite or cotton fibrous pads might be used as alternatives.

After pre-filtration the beer is then transferred into a finishing storage tank for another storage period of about one to five days during which time final carbonation is accomplished. Following the finishing period the beer is polish filtered. The beer is then in a form as found in the final product when purchased by the consumer.

During the course of the processing subsequent to fermentation, several treatments have become standard which serve to stabilize and make the final product more desirable in many respects. The beer may be treated with a clay for chill-proofing purposes in accordance with the method described in United States Patent No. 2,416,007, dated February 18, 1947. That patent teaches the addition of an aqueous suspension of suitable clays into the beer for removing foreign or partially soluble substances from beer such as undesirable proteins or proteinaceous complexes.

A number of improvements have been made upon said patent most of which include the preparation of an aqueous suspension of the clay prior to its addition to the beer. The present method is a further improvement upon said patent and prior techniques in that the aqueous suspension is avoided and the clay in dry form is added directly to the beer.

The most significant phenomenon that has been observed when dry clay is added to beer as opposed to aqueous suspensions of clay is that the clay does not swell as in aqueous addition techniques. This difference in the properties of the clay between the two types of addition is most important from an economic standpoint. In the aqueous addition of the clay the fully hydrated clay flocks and precipitates forming a sediment or sludge on the bottom of the treatment tank. When clay is added dry to beer it remains in the beer in particle size and no flocculation as such occurs.

Specifically, the practical advantage which follows from the use of dry clay includes the ease with which the beer may be finally filtered because of the simplicity of separating the non-flocculated clay after it has performed its function. Most important, the use of dry clay greatly reduces the volume of the trapped beer in the clay because of the non-flocculated, high density characteristics of the clay when added dry. This means a higher yield of beer per unit of beer-making ingredients.

In all respects the present method is similar to the prior methods of treating beer except that. the clay is added in dry form and at the point in the processing where the pro-filtration occurs. Aside from this difference all other prior techniques for treating the beer may e used as desired. Thus the various other treatments for stabilizing and clarifying beer may be used in addition to the clay treatment. These additional steps may include the use of reducing agents such as potassium metabisulfite, or preferably S0 gas itself, in accordance with United States Patent No. 2,916,377, dated December 8, 1959. It is also common to employ a proteolytic enzyme such as bromelin and/ or papain. The use of these other materials in the presently improved process is unchanged in any significant respect from prior techniques such as quantity of these other materials which may be employed or the point in the brewing process where they may be added. For example, when S0 gas is used, it may be introduced in the range of 5 to 30 ppm. and the enzyme dosage may be between 50015,000 activity units per barrels of beer processed, and they may be added at any point after fermentation, individually or simultaneously.