Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/313

regular. Grain is required by law to be kept at least 168 hours on the floors, but maltsters may keep it there as much longer as they like. Barley throws out five rootlets, the middle one being the strongest ; and if the young floor has been neglected, this will shoot out three times the length of the others and turn up at the end like an awl. When the grain has germinated sufficiently, its growth is arrested by placing it on the kiln, the object being to drivo off superfluous moisture and insure the keeping qualities of the

malt.

Kiln-drying.—The kiln is a chamber of which the floor should be made of woven-wire or sheet-iron, or of perforated tiles. The perforations are necessary to give admission to the hot air, and also to allow the detached rootlets to fall through. The kiln should have a sufficient area to allow the whole of one steeping to be dried at once, at a depth of 8 or 10 inches ; by which means the malt is more regular than when dried in two or three lots, as the portion left on the floor will grow, notwithstanding the maltster s efforts to prevent it. The opening at the top of the kiln is covered with a cowl or cupola, which answers the double purpose of excluding rain and allowing the escape of the steam. The furnaces are placed under the floor, nearly in the central line, and the hot air passing through the perfora tions dries the malt, while the steam is carried off through the vent in the roof. An iron or stone plate, 4 or 5 feet square, called the " disperser," is placed over each fire to disperse the heat and prevent the malt immediately above from taking fire. The heat at first should not exceed 90; if higher it produces a hardening or vitrifaction of the starchy matter or dextrin, and also heightens the colour of the malt ; whereas, if the malt be freed from moisture at a low temperature it may afterwards be exposed to a high heat without gaining colour. The moisture being disposed of, the heat may be gradually raised to from 125 to 135 for India pale ale malt, and to 170 or 180 for ordinary pale malt, the difference in the kinds of malt being the amount of heat to which they are subjected on the kiln. During the process the fires should never be allowed to go. out, as the smell of a green fire imparts an unpleasant flavour. During the last few hours in particular there should be a bright, clear fire for finishing off the malt, otherwise the beer will not get bright. It will thus be seen that the pro cess of kiln-drying is very important. Dr Ure s remarks on it are pregnant with meaning. He says, " The opera tion of kiln-drying is not confined to the mere expulsion of the moisture from the germinated seeds, but it serves to convert into sugar a portion of the starch which re mains unchanged, and that in a two-fold way. This is, first, by the action of the gluten upon the fecula at an elevated temperature, as also by the species of roasting which the starch undergoes, and which renders it of a gummy nature. If we dry one portion of the malt in a naturally dry atmosphere, and another on a moderately warm kiln, the former will yield less saccharine matter than the latter. Moreover, the kiln-dried malt has a peculiar agreeable and faintly burnt taste, probably from a small portion of the empyreumatic oil formed in the husk, which not only imparts its flavour to the beer, but also contributes to its preservation." Kiln-drying takes from one to four days, according to the depth of malt and amount of heat used. The fire being kept always bxirning, great care is needed to prevent its breaking out in the night ; it is there fore made up the last thing and then " banked up," that is, covered with a quantity of the ashes which fall through the bars. For ordinary pale malt, about three hours before it is thrown off the kiln the heat is raised from 150 to 1 80, and during this process it requires turning two or three times, and is thrown off the kiln in a hot state. The rootlets are readily detached from the malt by the turning on the kiln, and the treading of ths men in their list slippers ; they are finally separated by screening, and are the best criterion of the colour of the malt, showing at once the amount of heat used. These malt " combs" or " cummings," as they are called, are valuable food for cattle in winter ; and the fine ones which fall through the kiln- floor on the disperser, mixed with the dust from the fire, are said to be almost equal to Peruvian guano as a top dressing for turnips.

Malt continues to swell, by absorbing moisture from the atmosphere, for nearly three months, the time vary ing according to the dampness of the air. Malt in store is said to be mellowing. The increase by measure of malt over dry barley, called the "outcast/ is from 3 to 8 per cent. ; in bigg the increase scarcely amounts to 1 per cent. During the process of malting barley loses one- fifth of its weight ; in other words, 100 Ib of barley con verted into pale malt weighs on an average 80 ft) ; but as barley when kiln-dried loses 12 per cent, of moisture, the actual loss is reckoned at only 8 per cent. The late Pro fessor Thomson thus accounted for it:—

Soluble matter carried off by steep-water 1 "5 Carbonic acid formed and given off during germination... 3 Koots 3 "0 Waste (bruised and lost grains) 5 Dr R. D. Thomson, who made various experiments on malt for the purpose of ascertaining its feeding and fattening properties, states the loss sustained to be

Water 6 00 Saline matter 48 Organic , 12 52 19-00

Bigg sustains a greater loss than barley, amounting to 7 per cent. more. The great similarity which chemical analysis shows to exist between barley and malt, proves that malting is only the beginning of the process by which saccharine matter in solution is obtained. A glance at .Stein s analysis of the two will show this:—

Barley. Malt. Soluble albuminous compounds.... Insoluble ,, ,, Husk 1-258 10-928 19-854 1-985 9-771 18-817 Dextrin . 6-500 8-232 Fatty matter 3-556 8-379 Inorganic, matter. . 2-421 2-291 Extractive matter .. 0-896 4-654 Starch .. . 54-282 50-871 Loss 305 100-000 100-000

The following is the composition of barley and malt, as given by Oudemans:—

Hurley. Malt. Air-dried. Atr-drlcd. Kiln-dried Palo. Kiln-dried Amber. Produce of torrification... Dextrin o-o 5-6 o-o 8-0 7-8 6-6 14-0 10-2 Starch 67-0 58-5 58-5 47-6 Suear . .. o-o 0-5 07 0-9 i Cellulose 9-6 14-4 10-8 11-5 Albuminous substances. . Fatty ,, Ash kc 12-1 2-6 3-1 13-6 2 2 3-2 10-5 2-4 2-7 10-5 2-6 2-7 100-0 100-0 100-0 100-0

Albuminous compounds in barley and malt (Oudemans)—