Page:The New International Encyclopædia 1st ed. v. 03.djvu/534

* BREWING. 472 BREWING. ■which is one of the oldest (see Beeb), has been improved from time to time so that at the present day, by the aid of eliemistrj' and bac- terioloj,'y, the manufaeture of beer involves a liigh degree of teohuical skill. W bile it is usual to speak of the niauulacture of beer as brewing and the place where it is made as a brewery, yet to be more e.aet, there are two distinct and separate processes to be considered, tlic malting and brewing proper. Malting. The raw materials for making beer are water, barley, and hops, and the first process in the manufacture is the malting of the barley. The grain is first steeped by placing it in wooden or metal cisterns and covering it with cold water. This process of steeping lasts from 72 to S)6 hours, the water being drafned ofi' about once a day and replaced by fresh water. During the process of steeping, the barley absorbs a portion of the water, which causes it to swell and soften. After being finally drained, the barley is taken from the cisterns and spread to a depth of from one foot to one and a half feet on the malt-house floor. This part of the process is known as "couching.' In this position the grain begins to germinate or throw out the sprouts, which, if allowed to develop, would form the future root- lets and blades of the barley. This process is one which the maltster watches with the utmost care, since upon its being properly accomplished depends much of the final success of the brew. The chief requisites to be observed are that the germination shall be slow and regular; that it shall not proceed at too high a temperature, and that it shall be cheeked at the proper time. Dif- ferent varieties of barley germinate with diflerent speeds, and the maltster has to study the pecu- liarities of each variety and regulate his work accordingly. This regulation is accomplished by thinning out the couches; by regularly turning the grain over and respreading it: by letting in or shutting out the warmer or the colder outside air, and by resprinkling the grain with water. The thinning down of the couches is technically known as 'flooring.' The duraticm of the pro- cesses of cduching and flooring is usually from ten to twelve days. The next step is to check the germination, and this is done by kiln drying. The dry kiln consists of a building with one or more, generally two or three, drying-floors, which is heated to a temperature gradually increasing to the maximum recjuired, which may be from 'J0° to 100° F. for pale malt, to from 150° to 170° F. for brown malt. For drying the malted grain is spread out on the floors of the dry kiln, and when it is fully dried it is quite crisp. In this condition the grain or malt can be stored for brewing at any time. Brewing. The first operation in brewing is to crush, or technically to 'bruise,' the malted grain by passing it between iron rollers, the ground product from which is termed 'grist.' The grist is then mixed mechanically with hot water until it has about the consistency of ordinary porridge, and is then run into the nuilt-tubs. where the temperature is raised to about 170° F. Often the mash-tubs are provided with mechanical mixers for agitating the mixed grist and water which is now called the 'mash.' It is at this point in the process that adulterants are added if they are used. After standing in the mash- tub from two to three hours the liquor is drained off from the bottom, hot water l)eing slowly and evenly run over the top of the mash thoroughly to wash or purge the grist from the liquor, which is now called 'wort.' The wort is allowed to stand for a brief time to clarify, and is then drawn ofl' into cojiper boilers where it is boiled with hops. From one to four bushels of malt and from one to five pounds of hops are used for a barrel of beer. After being boiled for about two hours in the cop])er boilers, the wort is drawn otl' and cooled quickly by passing it through vessels containing coils of "pipe in which cold water circulates, or by some other means for rapid cooling, and then run into the vats where fermentation takes place. (See Fermentation.) Fermentation is started by adding about one gallon of liquid yeast to one hundred gallons of wort, the yeast used always being some which has been reserved from a previous l)rewing of the same kind of beer. Fermentation is allowed to progress for from six to eight days. It is com- paratively slow at first and then rapidly in- creases as the wort commences to 'work' until the temperature has risen considerably; large quantities of carbonic-acid gas are thrown off and the surface of the w'ort is covered with a thick layer of scum. The next process is to run the fermented liquor into other vats, known as cleansing-vats, which are usually provided with some means for cooling their contents, where a mild process of fermentation occurs, which throws oft' the remnants of the yeast in the shape of scum. The liquor is then drawn ofl' into casks where it is stored, for a greater or less length of time and under ditTerent conditions of tempera- ture, to mature. The time required and con- ditions provided for maturing several of the more common varieties of beer are diflerent in their precise natures and are discussed under Beer. Technology and Chemistry. The two preced- ing paragraphs outline briefly the processes of malting and lirewing. To describe the technology and clicmistry of these processes in nontechnical language is rather ditheult. Briefly enumerated, the technical considerations which call for the most particular attention are: (1) The nature and (jualily of the grain used; (2) the malting of the grain; (3) the tem|)erature at the com- mencement of mashing and again at tlu' begin- ning of fermentation; and (4) the quality of the w'ater used. It is imiiossible to enter into these technical questions in detail here, but some brief indications of tlu'ir character may be given. Re- garding the choice of Uirleys for brewing, they should be tlionaiglily ripened and should be care- fully hiirvested and handled to preserve the skin or husk of the kernel, since when the kernel is bruised or has its skin broken mold is likely to attack it and cause trouble, if not disaster, in malting and brewing. The precautions to be taken in malting have already been described. Regarding the incipient temperature of the mash iind of the wort at the commcncenieut of fermen- tation, it can only be said hect to the water used, the jnincipal require- ments are that it should be al)solutely pure and should be somewhat 'hard,' that is, it should contain lime salts. The principal chemical ac- tions occur during malting, when the mash is lieing made, and during fermentation. Durini; malting the albuminous substances in the grain