Today in 1965, US Patent 3193395 A was issued, an invention of Merritt V DeLano Jr. and Donald C. Tabler, assigned to the Phillips Petroleum Co., for their “Concentration of Beer by Crystallization.” There’s no Abstract, although in the description it includes this summary:
It is common to concentrate aqueous solutions by evaporation of water for the sake of economy in storage and shipping and to preserve the product. Removal of water by evaporation from a food product and particularly from a beverage results in the removal of essential components which affect the freshness and flavor of the beverage so that it cannot be restored to its original quality merely by the addition of water. This disadvantage can be overcome in the concentration of beverages by using a crystallization process whereby the water is separated from non-aqueous components by freezing. It is known that when water freezes the ice is in a pure form so that water can be removed from aqueous solutions by this method without the loss of volatile materials essential to the quality thereof.
There is considerable interest in the concentration of beer by freezing. The beer as received from the fermenters can be concentrated to approximately 1A its original volume by freezing out much of the water present therein. If the beer is shipped in the concentrated form, considerable savings can be realized in freight. Also, the storage facilities for the beer concentrate can be reduced and it has been found that beer in the concentrated form can be stored for substantially longer periods of time without deterioration of avor. Even if the beer is immediately reconstituted, there is substantial advantage to the concentration process in employing the crystallization method since the cold beer concentrate can be filtered to produce in effect an accelerated lagering process. This greatly reduces the requirements for large inventories and refrigerated storage tanks now necessary in breweries.
In the above-mentioned patent to Thomas, 2,854,494, there is disclosed a process and apparatus for purifying crystals which involves moving a mixture of crystals and mother liquor through a purification column in which the crystals are passed in a compact mass into a body of crystal melt which is displaced back into the crystal mass. The purification column includes an upstream liquid removal zone, a middle reflux zone, and a downstream melting zone. Mother liquor is removed from the crystals in the liquid removal zone and the ice crystals are melted in the melting zone. A portion of the crystal melt is Withdrawn from the melting zone and the remainder is forced back into the crystal mass in the reflux zone.
This apparatus can be used very effectively in the freeze concentration of beer. The beer is cooled to form a slurry of ice crystal in a mother liquor which is a beer concentrate and the resulting slurry is passed into the crystal purification column. Substantially pure water water which is the crystal melt can be removed from the melting zone and the beer concentrate is removed from the liquid removal zone of the purification column. We have found, however, that in the application of this purification method to beer, considerable difficulty is encountered as a result of carbon dioxide evolving from the mother liquor in the purification column. This evolvement of carbon dioxide causes channeling within the 3,193,395 Patented July 6, 1965 crystal mass with resultant loss of efficiency of the purification column. It becomes apparent, therefore, that the removal of carbon dioxide from the beer prior to its introduction into the crystal purification column should provide a solution to this problem. It can be appreciated, however, that with the removal of carbon dioxide from the beer prior to concentration there is also a substantial danger of removing alcohol and some of the essential flavor components which the crystal concentration method is used to preserve.
According to our invention, beer is concentrated by the crystallization method employing a purification column as described and the problem of channeling within the purification column as a result of evolvement of carbon dioxide is overcome by the prior removal of carbon dioxide without any substantial removal of the essential components from the beer itself. Since carbon dioxide is always added to beer in a carbonation step prior to packaging, this prior removal of carbon dioxide from the beer before concentration does not pose any particular problem or introduce an additional step in the over-all process of treating the beer concentrate on reconstitution. According to our invention, an antifoam agent is first added to the beer as it comes from the fermenters. The beer is then cooled in order to freeze a substantial amount of the water present therein and form a relatively thick slurry. This slurry is then subjected to a vacuum and the slurry is agitated with the result that carbon dioxide is removed from the remaining liquid. The solids content of the slurry can then be adjusted if necessary for the concentration process and the slurry is passed into the purification column where the ice and mother liquor are separated as described above. In a preferred aspect of the invention, in the carbon dioxide removal step the beer is cooled so that the slurry has a high solids content and subsequently the slurry is warmed slightly and thereby thinned so that trapped bubbles of carbon dioxide are released. The slurry is then recooled to the proper solids content for passage to the purification column. By lowering the temperature of the beer in order to remove carbon dioxide so that a substantial amount of water is frozen, the solubility of the carbon dioxide in the overall slurry is reduced even though the reduced temperature permits higher solubility in the remaining liquid. Reducing the pressure permits substantially all of the carbon dioxide to be removed from the slurry and since the alcohol has a very low vapor pressure at the low temperatures employed, very little of this material is vaporized with the carbon dioxide. We have also found that the addition of the antifoam agent to the beer prior to cooling to form a slurry enables substantially complete removal of the carbon dioxide from the slurry whereas complete removal is not attained without this antifoam agent, apparently because of the formation of extremely fine bubbles of the gas within the crystal mass.
It is an object of our invention to provide an improved method of concentrating beer by crystallization. Another object is to provide a method of concentrating beer by using a crystal purification column. Still another object of our invention is to provide a method of removing carbon dioxide from beer prior to concentration of the crystal slurry of the beer in the purification column without removing substantial amounts of alcohol. Still another object is to provide a method of improving the efficiency of a crystal purification column in the concentration of beer by substantially complete removal of the carbon dioxide present in the beer prior to passage of the crystal slurry through the purification column.