190 



SOME OP THE PRINCIPLES OP BREWING 



tanks (50-barrel capacity) in the form of a truncated 

 cone, open at the top, and provided with a coil of 

 pipe in the bottom to regulate temperature. 



Bottom -fermentation beers. — In lager-beer mak- 

 ing, after the tanks are filled with the freshly 

 aerated, pitched wort, the fermentation sets in 

 slowly at first. Within fifteen to twenty -four 

 hours, small bubbles of gas appear around the 

 the walls of the tank, and the whole surface is soon 

 after covered with a fine white foam or froth. 

 This gradually increases in amount, but remains 

 thickest at the walls of the tank. When the foam 

 becomes a certain depth, owing to the active fer- 

 mentation, a breaking up into rounded masses is 

 seen, and a general movement from the walls 

 toward the middle of the tank. This is known as 

 the "Kraiisen" or "cauliflower" stage, from the 

 resemblance of the masses of foam to heads of 

 cauliflower. Two stages of '' Kraiisen " are recog- 

 nized — " young Kraiisen " and " high Kraiisen." 



As a large amount of heat is developed by fer- 

 mentation, it is necessary to keep the solution dur- 

 ing this period down to about 50° Pahr. by means 

 of the attemperators, and, as soon as the fermenta- 

 tion slackens in activity, the temperature is brought 

 to 39° to 40° Pahr. 



The whole period of fermentation is of eight to 

 sixteen days' duration. During this time, the color 

 of the beer deepens, and the suspended yeast and 

 other materials should collect in little flecks, leav- 

 ing the beer perfectly clear. A large amount of 

 yeast is developed during fermentation, as the 

 sugar is transformed to alcohol and carbon dioxid. 

 The carbon dioxid escapes as gas, displacing the 

 air over the fermenting liquid in the vats. About 

 one-fifth of one per cent remains in solution. 



The amount of solids in solution is determined 

 by an instrument known as a saccharometer. As 

 fermentation proceeds the readings become less 

 and less, showing the " attenuation " of the beer. 



When the principal fermentation is at an end, 

 the beer is practically ready for the storage vats, 

 where it undergoes the secondary fermentation. 

 During the primary fermentation the sugar is not 

 all destroyed, and this residue of maltose and some 

 of the malto-dextrin are now slowly acted on by the 

 yeast, and eventually become very clear. The dura- 

 tion of storage depends on the destiny of the beer ; 

 if for present use, a quick treatment with clarifica- 

 tion is employed ; if for export, a storage period 

 varying from six weeks to three months follows. 



(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 

 Pahr., — 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. 



Por 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. 



