Page:The American Cyclopædia (1879) Volume III.djvu/264

 258 BREWING nels, and a white elevation is formed which separates into three or more radicles. About 24 hours after this, generally toward the end of the third day, the plumula, called the aero- spire, appears at the same point, and turns back under the husk, toward the other end of the seed, and would there issue as a green leaf if its growth were not arrested. Consequently the couch is spread out till it is not more than eight or ten inches deep. The temperature, however, continues to rise until the end of the fourth day, varying somewhat, according to circumstances, until it has reached 80 F. This is thought by the best maltsters in this country to be the limit to which it should be allowed to go ; and they keep the grain at this tem- perature until the sprouting has proceeded al- most far enough. Then the beds are spread still further, with great care. This is a critical time, and requires much judgment on the part of the maltster. The acrospire has now very nearly reached the other end of the seed, and the transformation of the starch has been car- ried as far as desirable. The barley, or malt, as it may now be termed, is carefully turned over two or three times a day, being spread more at each turning, until at the end of the process the depth is only three or four inches. This constitutes the flooring, as it is technically termed ; but the couching, sweating, and floor- ing are only different stages of the same pro- cess. The temperature at the last spreading is said to be in England about 62 F., and in Scotland, five or six degrees lower. In this country careful maltsters keep the temperature near 70 till very near the close, alleging that by not too suddenly checking the growth of the sprout they secure more uniform develop- ment. The couching and flooring occupy about two weeks in England, and in Scotland a some- what longer time. In this country the grain is usually kept on the floor about nine days in the most favorable weather, and in the spring and fall sometimes only seven or eight days. It is the object of some maltsters to convert as much of the starch as possible into sugar, while others rely upon accomplishing this in the kiln, and in the succeeding operations of the brewer. While the acrospire has been grow ing a wonderful transformation has been going on within the seed. The contents have become whiter, and crumble between the thumb and finger like meal. The albumen has disappeared and the gluten has diminished in quantity. About half of the starch remains unchanged, but the other half has been converted into dextrine and grape sugar. If the germination continued, the roots and stem would appro- priate these substances in their growth. The unchanged starch is not lost, but is converted into sugar in succeeding processes. How has this transformation been accomplished ? At the commencement of germination, in malting, as well as when a seed is placed in the earth, a substance is formed at the base of the sprout by a change which has taken place in the albu- men in consequence of the influence of the vitalizing principle in the germ, which has been awakened under the influence of heat and moisture. This substance is called diastase,and possesses the power at ordinary temperatures of converting starch into dextrine and grape sugar. This transformation can also be effected by gluten, but it requires a longer time. In malting, if the germination is allowed to pro- ceed until the rootlets and stem attain a certain size, it will be found on examination that all the starch, sugar, and gluten have disappeared ; the starch having passed into the soluble con- dition of sugar, and, together with the gluten, having been appropriated by the growing stem and fibrils. The object of the maltster in causing germination is, through the action of diastase, to convert the starch of the grain into dextrine and grape sugar, which is the natural sugar of vinous fermentation. When the great- est amount of dextrine and sugar has been pro- duced, with the least loss in the growth of the rootlets and plumula (acrospire), the operation is arrested by subjecting the malt to the heat and dry air of the kiln. The malt kiln is a chamber having a floor made of sheet iron, perforated with numerous holes sufficiently small to prevent the grain from falling through. This floor is heated by an ascending current of hot air, by means of 'a furnace below, which not only warms the iron floor, but passes up through the malt, warming and drying it at the same time. The malt should be spread upon the floor about five or six inches deep and raised to a temperature of 80 F., the heat gradually increasing until at the end of the operation it has reached 130 or sometimes 140. The malt is to be turned over about every three hours, until toward the close, when, the heat increasing, it should be turned every hour, to secure even drying and even color. Kiln-drying usually takes two days, including the time occupied in placing the malt in the kiln and removing it. It is then taken to an- other apartment and spread out, or it may be put in heaps and further manipulated and im- proved in color. When it is desired to make beer of a deep color, the heat of the kiln is in- creased. For the brewing of porter, a portion of the malt is almost charred, or the whole of it may be made of a deeper color. When taken from the kiln the grain has lost about 20 per cent, of its weight before steeping; but as the raw grain would have lost by the same degree of drying 12 per cent., the loss occasioned by malting is only about 8 per cent. The kiln not only dries the grain and prevents the fur- ther growth of the rootlets and acrospire, and thereby the loss of sugar, but also serves to convert a considerable portion of the unchanged starch into dextrine. Good malt is plump, sweet to the taste, has a pleasant odor, breaks easily between the teeth, and is full of soft flour. Barley of one grade and age only should be used at one steeping, as new barley germinates more quickly than old. After kiln-drying, the