The Theory and Practice of Brewing

by Michael Combrune

This process is intended to furnish proper means, for setting the constituent principles of the grain in motion: so that the oils, which before served to defend the several parts, may be enabled to take their proper stations.—This is effected by steeping the barley in water, where it strongly attracts moisture, as all dry bodies do; but it requires some time before the grain is fully saturated therewith.[8] Two or three days, more or less, are necessary, in proportion to the heat of the air; for vegetables receive the water only, by its straining through the outward skin, and absorbent vessels, and their pores are so very fine, that they require this element to be reduced almost to a vapor, before it can gain admittance. Heat hath not only the property of expanding these pores, but perhaps also that of adding to the water a power more effectually to insinuate itself.

By the water gaining admittance into the corn, a great quantity of air is expelled from it, as appears from the number of bubbles which arise on its surface when in contact with the grain, though yet much remains therein. A judgment is formed that the corn is fully saturated, so as not to be able to imbibe any more water, from its turgidity and pulpousness, which occasions it readily to give way to an iron rod dropped perpendicularly therein. At this time the water is let to run, or drawn off, the grain taken out of the cistern, and laid in a regular heap, in height about two feet. We have before accounted why moist vegetables, when stacked together, grow hot; so doth this heap of barley. The heat, assisted by the moisture, puts in motion the acids, oils, and elastic air remaining in the corn, and these not only mollify and soften the radical vessels, but, with united power, force the juices from the glandular parts into the roots, which are thereby disposed to expand themselves, and impowered to convey nourishment to the embryo enveloped in the body of the grain. The corn in this heap, or couch, is however not suffered to acquire so great a degree of heat, as to carry on germination too fast, by which not only the finer but also the coarser oils would be raised and entangled together, and the malt when made become bitter and ill tasted; but before the acrospire is perceived to lengthen, the barley is dispersed in beds on the floor of the malt house, and, from being at first spread thin, gradually, as it dries, and as the germination is thereby checked in its progress, it is thrown into larger bodies; so that, at the latter part of this operation, which generally employs two days, much of the moisture is evaporated, its fibres are spread, and the acrospire near coming through the outward skin of the barley. By these signs the malster is satisfied that every part of the barley has been put in motion and separated. It is of great consequence, in making of malt, that the grain be dried by a very slow and gradual heat: for this purpose it is now thrown into a large heap, and there suffered to grow sensibly hot, as it will in about 20 or 30 hours: thus prepared for drying, in this lively and active condition, it is spread on the kiln; where, meeting with a heat superior to that requisite for vegetation, its farther growth is stopped; though, in all probability, from the gentleness of the first fire it ought to be exposed to, none of the finer vessels are, by this sudden change, rent or torn, but, by drying, only the cohesion of its parts removed, rendered inactive, and put in a preservative state. Often, to a fault, the drying of a kiln of malt is performed in 6 or 8 hours: it would be to the advantage of the grain that more than double this time was employed for any intent whatever. It may here be observed, that those oils, which in part form the roots, being with them pushed out from the body of the corn, and dried by heat, are lost to any future wort, not being soluble in water; which is likewise true of those oils which are contained in the shoot or plume; so that the internal part of the malt has remaining in it a greater proportion of salts to the oils than before, consequently are less viscid, more saccharine, and easier to be extracted.

In this process, the acid parts of the grain, though they are the most ponderous, yet being very attractive of water, become weaker, and, by the continued heat of the kiln, are volatilized and evaporated with the aqueous steam of the malt. Thus, by malting, the grain acquires new properties, and these vary at the different stages of dryness; in the first it resembles the fruits ripened by a weaker sun, and in the last those which are the growth of the hottest climates.

When the whiteness of the barley has not been greatly changed by the heat it has been kept in, it is called pale malt, from its having retained its original color; but when the fire in the kiln has been made more vehement, or kept up a longer time, it affects both the oils and the salts of the grain, in proportion to the degree of the heat, and to the time it has been maintained, and thus occasions a considerable alteration in the color. Actual blackness seldom is, and ought never to be, suffered in malts; but in proportion to the intenseness of the fire they have been exposed to, the nearer do they come to that tinge, and from the different brown they shew, receive their several denominations.

The condition the barley was gathered in, whether green or ripe, is also clearly discernible when it is malted. If gathered green, it rather loses than gains in quantity; for the stock of oils in unripe corn being small, the whole is spent in germination, from whence the malt becomes of a smaller body, appears shrivelled, and is often unkindly, or hard. That, on the contrary, which hath come to full maturity, increases by malting, and if properly carried through the process, appears plump, bright, clean, and, on being cracked, readily yields the fine mealy parts, so much desired by the brewer.

The malts, when dried to the pitch intended by the maker, are removed from the kiln into a heap. Their heat gradually diminishes, and, from the known properties of fire, flies off, and disperses itself in the ambient air, sooner or later, as the heap is more or less voluminous; perhaps too in some proportion to the weight of the malt, and as the fire has caused it to be more or less tenacious. Nor can it be supposed that any of its parts are capable of retaining the fire in such a manner as not to suffer it to get away. So subtile an element cannot be confined, much less be kept in a state of inactivity, and imperceptible to our senses. Bars of iron, or brass, even of a considerable size, when heated red hot, cool and lose their fire, though their texture is undoubtedly much closer than that of malt or barley. The experiments made by Dr. Martine, on the heating and cooling of several bodies, leave no room to doubt of this fact, which I should not be so particular about, nor in some measure repeat, was it not to explain the technical phrase used by brewers, when they say, malts are full of fire, or want fire. Hence a prejudice hath by some been conceived against drinks made from brown malts, though they have been many months off the kiln, and have no more heat in them, either whole or ground, than the air they are kept in. The truth of the matter is, that, in proportion as malts are dried, their particles are more or less separated from one another, their cohesion is thereby broke, and, coming in contact with another body, such as water, strongly attract from it the uniting particles they want. The more violent this intestine motion is, the greater is the heat just then generated, though not durable. An effect somewhat similar to what happens on malt being united with water, must occur on the grain being masticated; and the impression made on the palate most probably gave rise to the technical expression just taken notice of.

The minute circumstances of the process of malting will be more readily conceived from what will hereafter be said. The effects that fire will have, at several degrees, on what, from having been barley, is now become malt, are more particularly the concern of the brewer; and that these differ, both as to the color and properties, is certain. A determinate degree of heat produces, on every body, a certain alteration, and hence, as the action of fire is stronger or weaker, the effect will not be the same as what it would have been in any other degree.

Barleys, at a medium, may be said to lose, by malting, one fourth part of their weight, including what is separated from them by the roots being skreened off: but this proportion varies, according as they are more or less dried.

As the acrospire, and both the outward and inward skins of the grain are not dissoluble in water, the glandular or mealy substance is certainly very inconsiderable in volume and weight: but as in this alone are contained the fermentable principles of the grain, it deserves our utmost attention.

We have before seen, that wines, beers, and ales, after the first fermentation, are meliorated through age by the more refined and gentle agitations they undergo, and which often are not perceptible to our senses. To secure this favorable effect, we must form worts capable of maintaining themselves, for some time, in a sound state. This quality, however, if not originally in the malt, is not to be expected in the liquor. Some objections have been raised against this method of arguing, and these aided by prejudices, often more powerful than the objections themselves. It is therefore necessary, as malting may be esteemed the foundation of all our future success, to enquire after the best and properest methods of succeeding in this process. Let us, for this purpose, reassume the consideration of the grain, as it comes from the mow, trace it to the kiln, and observe every change it undergoes by the action of the fire, from the time that it receives the first degree of preservation, to that when it is utterly altered and nearly destroyed.