(4) Finishing.
The beer finally undergoes a finishing process in the "chip cellar." The objects here are : (1) to produce a lively, that is, well-carbonated beer, either by adding "Kraiisen" or by carborating or both, and (2) to produce brilliancy, which is done by clarifying with isinglass or "chips," or by fil tration. "Chips" are small pieces of wood, which expose a large surface to the beer and to which suspended matters readily adhere.
The process of clarification by the use of chips or isinglass is known as "fining." After fining, the casks containing the beer are tightly bunged so that the solution may become charged with carbon dioxid and promote sedimentation of suspended material left in the beer. After the proper period for bringing about the desired results, the beer is "racked," that is, run off into the barrels or kegs, in which it goes to the trade.
Clarification by filtration is now much used. This process consists in forcing the beer under pressure through layers of wood-pulp, by which means the suspended matters are mechanically removed. The composition of a finished beer is obviously dependent on the amount of raw mate rials used, and the method of treatment employed. The amount of alcohol in ordinary beers varies from about 3.2 to about 4.5 per cent.
Top-fermentation beers.
Top -fermentation beers or "ale" differ from those previously mentioned in the method of treat ment, although in the main the equipment of the brewery is essentially the same. A carbonating room may take the place of the chip cellar.
In the preparation of present-use ales, about 70 per cent of malt and 30 per cent of unmalted grain is used (or 75 per cent malt and 25 per cent sugar). The mashing is carried out until conversion of the starch is complete, when the solution is bailed, the hops being added and run into the fermenting tanks. Here the phenomenon differentiating ale
fermentation from beer fermentation takes place After being pitched with the requisite amount o' yeast,—the temperature being not far from 60f Fahr.,—bubbles of carbon dioxid begin to rise to the surface in two to three hours. In two or three hours more the froth appears on the surface around the sides of the tank, and soon covers the whole surface. The "cauliflower stage" is reached and is followed by the "rocky head stage." Great masses or heads of foam are developed until they may attain a height of three or four feet above the surface of the wort, owing to the violent ebullition. The frothy appearance gives place to the more compact "yeasty head," which consists of masses of yeast carried up by the gas and accumulating at the surface.
About forty-eight hours after pitching, the yeast is in such amount that it is skimmed off, or removed, and this process is repeated from time to time, until the practical judgment of the brewer determines when to stop, After the active fermenta tion is over, the ale is allowed to settle for two days, when it is filled into the trade barrels, and to it is added 10 per cent of Kraiisen, taken thirty six hours after pitching.
For brilliant ales the treatment is nearly the same, but, in general, great care is taken in fining and the solution is carbonated.
Ales contain more alcohol than lager beers, while the amount of extract may be variable. The average of several samples of stock ale analyzed by Wahl and Henius gave 55 per cent. Cream and sparkling ales contain less alcohol, ranging from 4.0 to 4.90 per cent. Analyses of many samples show that American ales are less alcoholic than the English products.