The brewing of the matt comprehends no less than six stages. 1st. Grinding the malt, which may be accomplished in several ways: either by placing the malt between two revolving horizontal circular stones, such as are employed in flour-grinding; or passing the malt through a mill like a large coffee-mill; or bruising it between revolving steel rollers. The last plan is the best, as it is desirable that the grinding should not be too perfect, which would give a fine flour, readily becoming pasty on the addition of water. When coarsely bruised, however, the water can find its way into all parts of the grain, and thoroughly soak it. 2d. Mashing the bruised operation is conducted in a large tun, built up of wooden staves, and surrounded by hoops—somewhat similar in construction to an ordinary domestic churn. Water, which has been previously heated in a copper, is allowed to run into the comparatively cold mash-tun, while the bruised malt at the same time descends by the hopper, the water thereby becoming reduced to 1G0° F., or slightly below that temperature. The whole is then thoroughly agitated by long poles, worked by the hand or by machinery, till every particle of the malt is brought into contact with the water. The 'result is that the malt absorbs the water in part, and a very active change begins to take place. In the malt, there is developed a substance called diastase (q.v.), which reacts on the starch of the malted barley, and changes it into the variety of sugar called grape-sugar. See SUOATt. So rapidly does this transformation of starch into sugar occur, that almost immediately on the mixing of the water with the bruised malt, the liquid assumes a sweet taste. In the space of half an hour the temperature of the mash-tun will be found to have decreased to about 140° F.; and then a second quantity of water, at a heat of 190° F.. is run in, so as to raise the temperature to about 167° F., which degree of heat is found to be the best for enabling the diastase to act most powerfully in transforming the starch into sugar. After two or three hours' action upon the malt, the water, which is now very sweet to the taste, is drawn off into a large vessel called the underbaek, and fresh water, at a temperature of about 190° F., is admitted to the ton, and allowed to soak the malt still remaining there. This part of the process is styled the second mash; and as the water is at a higher temperature than in the first mash, much of the residuary matter In the malt is changed into sugar, and dissolved. After some hours, the liquid from the second mash is drawn off, and added to that of the first mash already in the underback; and a third quantity of water, at a still higher temperature, about 200° F., is run in upon the malt, which dissolves out all the remaining portions of any value, and leaves the husk skin of the grain and other insoluble matters. The liquid from the third mash is not strong enough to be in general mixed with the other solutions in the underback, and is either employed in brewing small beer, or is again heated and used in treating new bruised malt.
In order that the brewer may be enabled toprepare the same variety of clay after clay, it is requisite that the liquid in the underbaek, and which is now called the sweet•worts, should be of a definite strength; and to determine this, an instrument called a saecharometer, a form of areometer (q.v.), is used, which enables the brewer to deter mine the strength of the sweet-worts, and, if necessary, to add some of the liquid from the third mash, to reduce the strength of that in the underback.
In the drawing off of the several worts from the mash-tun, advantage is taken of a finely perforated false bottom of plate-lron, which lies about afoot above the true bottom of the tun, and the liquids being drained away through the perforations in the false bottom, the insoluble husk and other matters are left behind. The material left on the false bottom, called grains or draft, is used for feeding cattle.
3d. Boiling of the worts with reduced to the proper strength, the worts arc pumped up from the underback into a covered-in boiler or copper, and being mixed with hops, are raised to the boiling-point, and kept in a state of ebullition for some time. During the boiling, it is necessary to keep the hops and other sediment from set tling at theiower pant of the boy.er near the lire, and for that purpose a. Sort of rake with teeth, turned by a wheel above, is kept turning round, which tends to hold the sediment iu mechanical suspension. To economize heat, it is customary to have a tank fitted to the upper part of the boiler in which water or the worts can be heated. The hops which are obtained from Kent and Sussex are the strongest, and are employed in the brewing of porter, while the Worcester hop is milder, and is preferred for ale. The lops are useful in the brewing of B. in imparting to the liquor a volatile fragrant aro matic oil,. a bitter resin, and a little tannin. The quantity of hops required to be added depends much On the kind of 13. which it is intended to brew. The stronger the B. is to be, and above all, the more bitterness is required, the more hops must be added to the boiler. In common ale or B., the quantity of hops does not exceed 2 lbs. to the quarter of malt; whilst in bitter-beer, and especially that intended for foreign countries, the amount of bops is 8 lbs. and upwards. Besides imparting to the worts the active con stituents of the hop, the boiling operation serves other important, ends. In the sweet worts, there is a considerable quantity of nitrogenous matter, which is very liable to pass into decomposition, and which, were it to do so, would destroy the beer. During the boiling, the excess of this nitrogenous matter separates as a flaky and stringy called by the brewer mucilage. The boiling is continued till the hops have yielded their
aromatic and bitter principles, and till the liquid has been concentrated to the extent required by the brewer, and then the whole is run into the a form of cistern which has a false bottom composed of perforated iron plates, admitting of the liquid worts percolating through, while all the mucilage and other solid matters are retained on the upper surface of this metallic sieve. 4th. Cooling the the liquor drains through the false bottom of the hop-back, it is run on to the cooler or refrigerator, which, in size and appearance, resembles the ordinary wooden floor of a large room. The planks. are so closely connected together that the liquid cannot run through, and a ledge runs round the sides of the room, which is also tight. The hot worts, which are spread to the depth of a few inches over the floor, are very rapidly cooled down, by allowing a free current of cold air to pass over the top of the liquid, and often by hav ing a series of fans revolving rapidly immediately above the liquid, so as to cause a more speedy removal of the heated air loaded with steam, and the substitution of cold air. Occasionally, the brewer is at the expense of having a coil of metal pipe, placed up and down the floor of the cooler, through which metal pipe cold water is allowed to run at the time the hot worts are being cooled down. By these means the worts are very soon reduced to a temperature of about 60' F. This step in the process of brewing is a very important one, as, if the cooling is not conducted with the greatest rapidity, the sugar in the worts will become partially converted into acetic acid, or, as it is termed, foxing occurs, which communicates bad properties to the worts, and ultimately produces a beer with an unpleasant taste and flavor. 5th. Fermenting the the liquid has been cooled down to 55' to 60° F., it is conveyed to the fermenting tun, where it is mixed with the yeast (q.v.), and the process of fermentation proceeds. The tun or vat is formed of strong wooden staves, and is either circular or square. The latter form has recently been introduced, and appears to be preferred by some brewers. The yeast is added 111 varying quantity, according to the strength of the worts, but the more common amount is one gallon to every 100 gallons of the worts. Very soon after the yeast is mixed with the worts, the whole contents of the tun begin to pass into a state of com motion, much as is evolved, and this, tending to escape, causes a frothing on the sur face of the liquid termed the rocks, from the irregular mountainous appearance of the masses of froth piled on each other. The color of the froth at this period indicates the quality of the beer. Thus, if the froth appears of a yellowish-white or yellow tint, the operation is going on satisfactorily; but if the color darkens to a brownish yellow or a light brown, it is considered a bad sign, and the beer is spoiled as a first-class beverage. The chemical changes which occur during the process of fermentation (q.v) are due to the action of the particles of yeast on the sugar or saccharine matter. This action pro ceeds most satisfactorily at a temperature of 72° F., and care is taken in the brewing of the finer varieties of B., such as India pale ale and bitter-beer, that the temperature never exceeds 72° F. cl'he grape sugar which is present in the worts as they are introduced into the fermenting tun, is composed of carbon. hydrogen, and oxygen in the proportion Cm H14, 014; and when the yeast acts upon it, a greater or less proportion of it is con verted into alcohol, carbonic acid, and water. Thus, one atom of sugar, is converted into 2 atoms of alcohol (C,HSO1) = CR111204; 4 atoms of carbonic acid (CO2) — C40,; and 2 atoms of water (HO) — which, when added together. give the atom of sugar, CigH140,4. The carbonic acid tending to escape, causes the frothing or rocks, and the alcohol and water are left in the fermenting tun. During the prog ress of the fermentation, a considerable amount of new yeast is formed, which gets entangled in the froth; and when the operation slackens, and the frothy head begins to fall, the upper yeast is skimmed off. This process of the conversion of the sugar of the worts into alcohol or spirit, is termed attenuation (Lat. tennis, thin); and the degree to which the change is carried depends on the kind of B., and the market it is to be sent to. In sweet ale or 13., the attenuation is not allowed to proceed far, and much sugar IS left in the beer. Bitter-beer, however, is attenuated to a greater degree, and conse quently there is less saccharine matter left in it; while in India pale ale, and other beers intended to be sent great distances, the attenuation must be carried on much further, else the liquor would not be preserved during its transit to many parts of the globe. Gth. Clearing and 13., When properly fermented, is placed in casks like hogsheads, called where the remaining traces. of fermentation proceed, and the B. ceases to appeal-thick or drumly, and becomes clear; when it is pumped up into store-casks of great size, or at mice placed in the casks in which it is sent into market. During the storing of the B., an extra quantity of hops is often added, to increase the bit Qrness and The principal constituents of the various kinds of 13. are water, alcohol, sugar, gum, gluten, and the bitter extractive matter of the hop. The amount of alcohol varies: in small-beer, it is only about 1 per cent; in ale. the stronger kinds of 13. and porter for home consumption, 5 to 7 per cent; in East India pale ale, 10 per cent. In II. intended to be forwarded to California from Britain, the attenuation is carried so far, that there is more than 10 per cent of alcohol, and the B. is then called dry.