Wheat, oats, rye, potatoes, and other amalyceous or starchy materials contain starch insoluble in water and to render it soluble, and to change the starch to maltose they must be mashed with a certain small proportion of malt,—or grain in which germination has been artificially induced and then interrupted at a certain stage. This increases the diastase contained in the grain so germinated, and this diastase is able to transform starch into soluble form. Hence, malted grain gives lightness and liquidity to the wash, and prevents the starch falling to the bottom of the mash tub or “back,” and also prevents the starch falling to the bottom of the still and consequent burning.

While all varieties of grain including rice are suitable for the preparation of malt, barley is preferred to all others, and is most commonly used.

The best barley for malting is that having the following characteristics; a thin skin; a mealy interior; grains of a uniform size; of the greatest weight; which has been stored for three months. Barley on harvesting has but slight germinating power. The reason for the uniformity in the grains lies in necessity of a uniform steeping of the grain so that the period of germination shall be the same for the whole mass.

Like all materials for distillation, the barley should be thoroughly cleaned of impurities—not only dust, seeds and weeds, but fungi and bacteria.

This may be partly accomplished in the ordinary fanning mills, usual on farms, but a better machine would be a “tumbling box” of wire mesh. This is inclined, so that grain put in the upper end, will pass downward to the lower, being thrown about as the box or cylinder is rotated. The dust, seeds, etc., fall through the meshes of the wire as do the smaller grains. After this cleaning, the barley should be thoroughly washed. This may be either done in the steeping vat itself—and the water afterwards drawn off—or in special machines. If the barley be allowed to soak in water for a day or two, the later washing will completely cleanse it. This preliminary cleaning is most important as impurities reduce the germinating power of the grain, as well as introduce bacteria inimical to fermentation.

Washing in some instances is done by forcing compressed air into the steeping tub, thus violently agitating and swirling the water therein, and washing away the impurities. Another method is by passing the steeped grains along a trough supplied with moving water, the trough being provided with rotary agitators. Any fairly ingenious mechanic could devise a capable cleansing machine. Care being taken that it shall not injure the grains.

After cleansing, the barley should be steeped. For this purpose tanks of metal or cement are to be preferred to wood. All vats should be kept thoroughly cleaned by frequent scrubbing with lime water.

The barley placed therein should at all times be entirely covered with fresh water to a depth of a few inches, and for the first few hours the grains should be carefully stirred in order that no grain should escape wetting. At the end of that time the still floating grains should be removed.

In 36 or 48 hours the grain will usually be sufficiently steeped,—but this varies with weather conditions. The warmer the water the quicker the steeping, and in winter proper steeping may not be accomplished before four or five days.

A simple test is to rub the grain strongly between the hands, If it is entirely crushed, and no solid matter is left it has been steeped sufficiently. Barley should be capable of compression lengthwise and the hull should become easily detached. It should be easily bitten, and not crack under the teeth. In order to prevent fermentation in summer, it is well to renew the water a few times during steeping. Over steeping is worse than under steeping.

After the barley is in proper condition the vat or tank is opened and the water drained away. The draining should be complete, and therefore the grain should be left to drain about 12 hours.

Germinating. The grain is now taken to the malting floor. In practice it is well to locate the steeping vat above the malting floor, so that the steeped grain may be run down on to the floor without inconvenience.

It is best to first spread the grains out on the floor to a depth of a few inches in order that it may somewhat dry out. This is not necessary when it has not been steeped to a great extent.

After 10 or 12 hours of drying, the grain is placed in a heap until warm to the touch, which may occur in from 12 to 24 hours. It is then disposed in a layer from eight inches to 20 inches thick. This is called the “wet couch.” The lower the temperature the thicker the couch should be. It should be turned every six or eight hours in this stage.

The heat so germinated after 25 or 30 hours produces at the end of each grain a small white rootlet. The grain in the middle of the layer is the first to sprout, as it is the warmest, hence the couched grain should be frequently turned so as to give all the grains a uniform heat, and a uniform germination. At this period the grains beneath the surface are dampish to the touch.

The height of the couch is now successively lessened to layers of from six to two inches called “floors,” the height of each floor of course depending on the temperature, as before.

It is to be understood that the growing grain requires both dampness and air, hence the “floor” should not be thinned so rapidly as to deprive it of moisture, and the barley should be turned at least twice a day to give each grain a proper aeration. During this period the small white rootlets or radicals should be white and shiny. If they begin to fade, it is a sign that they lack water and the grain should be sprinkled. Germination usually requires from a week to ten days, or sometimes two weeks, depending on the previous steeping, the quality of the grain and the temperature. When the fibers or rootlets of the grain are about equal to the length of the grain, germination is complete.

It used to be considered that malt was in its best condition in eight or ten days. To-day, however, “long malt” is used,—requiring a germinating period of twenty days, being frequently moistened and turned during this time, and the temperature being kept at 65° F. This malt is very strong in diastase.

The effect of germination is to produce a change particularly favorable to mashing. The barley becomes sweetish, the gluten is partially destroyed and what is left is soluble. Thus the fecula or starch is set at liberty and free to be acted on by the yeast used in fermenting.

March is the best month in which to malt; and while the malt is best used immediately, it can not be kept in its green state and must be therefore dried for future use.

Drying. This is accomplished either in the air of a warm, dry room in hot weather, or by means of a drying kiln. In the first process the malt is spread in a thin layer and frequently turned. In the second the grain is spread out in a layer from eight inches to a foot thick on the grain floor of the kiln.

Beneath the grain floor a fire is maintained. In the beginning the temperature of the drying floor should be about 85° F., but this is increased gradually to about 104° F. until most of the moisture has been removed. The heat is then raised to from 120° F. to 130° F., thus completely drying the grain.

The germinated green or dried barley is called malt. It is of good quality when the grain is round and flowery; when it crumbles easily and when its taste is sweetish and agreeable. Pale malt or that which has been hardly altered from its original color is the best for distillation.

Before the malt can be used it should be screened so as to remove the rootlets.

Two hundred and twenty lbs. of barley should yield from 275 to 350 lbs. of green malt, about 200 lbs. of air dried malt, and from 175 to 190 lbs. of kiln dried malt.

In large plants malting is now so carried on that the steeping germination and drying are all accomplished in one vessel or container, by one continuous operation. This vessel is commonly in the form of a drum of sheet iron, revolving at a very slow speed. Moist air is introduced and the carbonic acid laden air withdrawn. After germination the malt is dried by passing in dry air at the proper temperature.

As these systems are only adopted to large distilleries, using expensive machinery, further reference to them is not considered necessary in this volume.

Previous to use the malt must be finely ground or crushed either before or after mixing with the materials to be mashed. It is not necessary or advisable that the malt be reduced to flour. The use of malt with other materials in order to form a fermentible mash, will be considered in the chapters on specific mashes.