SOME OF THE PRINCIPLES OP BREWING 



189 



place on what are known as the growing floors or 

 malting floors, large cement floors in rooms kept 

 at the proper temperature and light regulation. 

 Of late years, mechanical devices have been intro- 

 duced so that most of the malting of today is done 

 by the "box" system, although some use of revolv- 

 ing drums is made. In tiie box system, the malt 

 after steeping is introduced into long box -like 

 compartments with perforated floors, through 

 which the properly warmed moist air passes. 

 Traveling over and along these boxes are stirrer- 

 like devices, which lift, stir, and aerate the grain. 

 As the grain is kept at favorable and constant 

 humidity and temperature, germination takes place 

 rapidly and in the course of a few days the acro- 

 spire or germinating sprout of the grain is well 

 developed, and the rootlets are apparent. 



In drum malting, a much smaller amount of air 

 is used than with the mechanical floors or boxes, 

 and there is also more uniformity in the treatment, 

 as the aeration, moistening, and the like can be 

 regulated nicely by mechanical means. The "drum" 

 consists of two concentric perforated cylinders 

 with the grain in the space between. The drums 

 revolve, thus keeping the grain in motion, and 

 causing more perfect aeration, as the grain in all 

 parts of the cylinder receives uniform treatment. 

 When the green malt has reached the desired stage 

 of growth, further change is prevented by quick 

 drying or "kilning." The green malt is carried by 

 conveyors to perforated floors below which are 

 furnaces, so that heat to any desired degree may 

 be applied. By the control of the two processes 

 of malting and kilning, the malt may be prepared 

 for the different kinds of beers indicated above. 

 Of all the ingredients used in brewing no other 

 one has so much importance as the malt, for the 

 character of the beer depends very largely on 

 it, beers of totally different character being pos- 

 sible because of the differences in chemical compo- 

 sition due to the varied malting processes. The 

 color of the beer is determined largely by the heat 

 applied in kilning; the chemical character by both 

 malting and kilning. The product now obtained is 

 known as malt, and presents the same general 

 appearance as the grain itself, except that it may 

 be much darker in color, owing to the roasting. 



(2) Preparation of the wort. 



The prepared malt is next to be made into a 

 "mash," from which the "wort" is obtained. The 

 malt is ground and mixed with warm water in the 

 proper proportion, and then heated in a kettle or 

 "mash tub," provided with a stirrer. This process 

 not only dissolves the maltose and the soluble 

 proteids already produced in the grain during the 

 malting period, but it also brings about further 

 conversion of starch to maltose, malto-dextrins, 

 and dextrin and liberates some of the enzymes, 

 which are developed in germination to a greater 

 amount than the starch-content of the grain de- 

 mands. It is therefore possible to introduce still 

 more starchy material in the form of corn-flakes 

 and the like, which the excess of diastase may con- 

 vert into fermentable sugar. 



The taps are then opened and the liquid part, now 

 known as the "wort," is allowed to run off ; the 

 spent grain is washed or "sparged" by sprinkling 

 with hot water several times. 



The wort is next boiled with the addition of hops. 

 The hops give a bitter flavor to the beer and aid 

 in its preservation ; moreover, the hop-oil ai)d 

 tannins seem to assist materially in the precipi- 

 tation of some of the proteid matter. The whole 

 process of boiling might be regarded as having 

 several results, e. g., destruction of diastase, pre- 

 cipitation of the proteids, concentration, extraction 

 of hop-oil and hop resin, and sterilization. 



After settling, the wort is again drawn off and 

 the residue sparged. The hot wort is then cooled 

 by passing over a large Baudelot cooler, or "beer- 

 fall," consisting of a series of copper pipes through 

 which cold water or a solution from a refrigerating 

 machine passes. The cooling is accompanied by 

 aeration, which is very desirable ; but great care 

 should be taken at this point to prevent infection 

 by bacteria and other microorganisms from the air. 

 Special devices to prevent this are in use in the 

 most scientific breweries. 



(3) Fermentation. 



After proper cooling and aerating, the fresh wort 

 is ready to pass to the fermenting tuns, and is 

 inoculated with yeast or " pitched." In case pure 

 cultures of yeast are not maintained for ferment- 

 ing, the yeast is frequently added to the wort in 

 the pan at the base of the Baudelot cooler, and the 

 whole mixed mass run through pipes to the fer- 

 menting room. When special pure cultures are 

 employed, a "pure culture apparatus" is necessary. 

 In this the yeast is developed, starting from a 

 single cell, until sufficient has been prepared to 

 "pitch" the whole volume of wort. 



As has already been stated, the top fermentation 

 is employed for ale, stout, porter, and Weiss beer, 

 and the bottom fermentation for lager and Ameri- 

 can steam beer. Bottom fermentation proceeds at 

 temperatures ranging from 42° to 51° Fahr., top 

 fermentation at 57° to 73° Fahr. The control of 

 temperatures in the fermenting cellar is therefore 

 a matter of importance. The bottom fermentation 

 proceeds somewhat the more slowly, requiring 

 eight to fifteen or sixteen days, while top fermen- 

 tation is finished in a few days. 



Fermentation may.be regarded as occurring in 

 two distinct stages: 



(1) The "primary" or "principal" fermentation, 

 in which the maltose is especially acted on at tem- 

 peratures of 42° to 51° Fahr., for bottom yeasts, 

 and 57° to 73° Fahr., for top yeasts. 



(2) The "secondary" or " after - fermentation," 

 in which the malto-dextrin is transformed by bot- 

 tom yeasts at 84° to 37° Fahr., and by top yeasts at 

 about 55° Fahr. The yeasts used should in either 

 case be freshly developed, free from contaminating 

 organisms, and in actively growing condition. The 

 amount added depends on a number of conditions, 

 so that the experienced brewer uses his judgment 

 rather than a definite rule. 



The fermenting tuns are generally large wooden 



