We may now follow through the actual processes comprehended in brewing.
(1) Mailing.
This is the general name given to the process whereby the starch of barley or other grain is changed to maltose by the diastatic enzyme. The product is known as " malt." The grain is carefully selected and cleaned, and then is subjected to a steeping process in "steep tanks," or big iron cylin drical hoppers with conical bottoms. The object of steeping is to soften the outer coating and promote rapid germination. When the steeping has been sufficient, the grain is carried to the place where germination takes place.
Until comparatively recently, the malting took 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 the 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 and 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.