The Theory and Practice of Brewing

by Michael Combrune

In the preceding enquiry, some of the defects of malt have been occasionally mentioned: but as a perfect knowledge of the grain, especially when it has undergone this process, is a matter of no small concern to the brewer, I shall now bring such defects into distinct view, both to compare them with the foregoing principles, and that the knowledge of them may be more at hand, on every occasion, when wanted.

Every different degree of heat acting on bodies causes a different effect: and this varies also, as such heat is more or less hastily applied. The growth of vegetables is in general submitted to these laws: but yet I conceive there is some difference between germination and vegetation, which I beg leave to point out. The former seems to be the act caused by heat and moisture, while the plume or acrospire is still enveloped within the teguments of the parent corn, and it is most perfectly performed by the gentlest action, and consequently by the least heat, that is capable of moving the different principles in their due order. Vegetation, again, is that act which takes place when the plant issues forth, and, being rendered stronger by the impressions of the air, becomes capable of resisting its inclemencies, or the warmth of the sun-shine. Germination is the only act necessary for malting, the intention being solely to put in motion the principles of the grain, and not to rear up the embryo to a plant. Now, as this begins in barley at the degree where the water first becomes fluid, or nearly so, the cold season, when the thermometer shews from about 32 to 40 degrees, would seem the most proper for this purpose. How far its latitude may with propriety be extended, experience alone can determine. Maltsters continue to work so long as they think the season permits, and leave off generally in May, when the heat of the water extends at a medium from 50 to 55 degrees. But the nearer they come to this medium, with the greater disadvantage must they malt: as, by such warmth, the vessels of the corn are much distended, the motion of the fluids violent, and the finer parts too apt to fly off. Thus the coarser oils gaining admittance, the glandular parts become filled with an impure and less delicate sulphur, which, instead of a sweet, inclines to a bitter, taste. This is so manifest, and so universally experienced, that, in general, brewers carefully avoid purchasing what is termed latter-made malts.

Malt, which has not had a sufficient time to shoot, so that its plume may have reached to the extent of the inward skin of the barley, remains overburthened with too large a quantity of earth and oils, which otherwise would have been expended in the acrospire and radical vessels. All those parts of the corn which have not been separated, and put in motion by the act of germination, will, when laid on the kiln to dry, harden and glutinize: no greater part thereof will be soluble in water, than so far as the stem or spire of the barley rises to, or very little farther, and as much as is wanting thereof will be lost to the strength of the drink.

When malt is suffered to grow too much, or until the spire is shot through the skin of the barley, which is not often the case, though all that is left be malt, that is, containing salts dissoluble in water, yet as too large a portion of oils has been expended out of the grain, such malts cannot be fit to brew drinks for long keeping.—There is, besides, a real loss of the substance of the corn, occasioned by its being overgrown.

Malt, the germination of which has reached and been stopped at the proper period, and has been duly worked upon the floors, if not sufficiently dried on the kiln, even though the fire be excited to a proper heat, retains many watery parts. The corn, when laid together, will be apt to germinate afresh, perhaps to heat so as to take fire; should not this extreme be the case, at least it must grow mouldy, and communicate an ill flavor to the drink.

Malt, well grown, and worked as before, but over-dried, though with a proper degree of heat, will become of so tenacious a nature, as to require a long time before it can admit of the outward impressions of the air to relax or mellow it, that is, before it is fit to be brewed with all the advantages it otherwise would have; and in proportion as it has black specks on being masticated, so much of its parts being charred is a diminution to the strength of the liquor, besides impressing it with a burnt or nauseous taste.

Malt, dried on a kiln not sufficiently heated, must require proportionably a longer time to receive the proper effect of the fire; the want of which will bring it into the same state as malt not thoroughly dried.

If too quick or fierce a fire be employed, instead of gently evaporating the watery parts of the corn, it torrifies the outward skin, divides it from the body of the grain, and so rarifies the inclosed air as to burst the vessels. Such is called blown malt, and, by the internal expansion, occupies a larger space than it ought. If the fire be continued, it causes its constituent parts to harden to the consistence of a varnish, or changes it into a brittle substance, from whence the malt is said to be steely and glassy: it dissolves but in a small proportion, is very troublesome and dangerous in brewing, and frequently occasions a total want of extraction; by the brewery termed, setting the grist.

Malt, just, or but lately, taken from the kiln, remains warm for a considerable time. Until the heap becomes equally cool with the surrounding air, it cannot be said to be mellow, or in a fit state to be brewed: its parts being harsh and brittle, the whole of its substance cannot be resolved, and the proper heat of the water, which should be applied to it for that purpose, is therefore more difficult to be ascertained.

The practice of those maltsters, who sprinkle water on malt newly removed from the kiln, to make it appear as having been made a long space of time, or, as they say, to plump it, is a deceit which cannot too much be exposed. By this practice, the circumstance of the heat, and harshness of the malt, is only externally, and in appearance, removed, and the purchaser grossly imposed on. The grain, by being moistened, occupies a greater volume, and, if not speedily used, soon grows mouldy, heats, and is greatly damaged.