A Practical Treatise on Brewing/Barley

Any kind of grain can be converted into malt: but in England it is most usual to employ barley for that purpose. There are three species of barley.

1. Hordeum Distichon, the common barley, characterised by two lateral rows of seeds on the spike. Professor Thomson’s experiments give 0.343 inch as the average length of a seed; 0.143 the breadth; and 0.108 the thickness.

2. Hordeum Vulgare, commonly termed Bigg in Scotland, having, according to Linnæus, two rows of seeds more distinct, and two imperfect ones.

3. Hordeum Hexastichon, with hermaphrodite flowers and six rows of seeds.—Records of General Science, vol. i. 441.

By the experiments of Professor Thomson in 1806, malt of bigg of that year was found inferior to that of English barley by 14 per cent.: the weight of the bigg being 48.848 lbs. per imperial bushel, while the barley weighed 51.444 lbs. From these experiments the excise duty on malted bigg was fixed at 16s. per quarter, whilst that on malted barley was 20s. 8d. per quarter.

Since 1806, from superior knowledge of agriculture, and the selection of improved varieties of the different grains, &c., both barley and bigg have much improved in quality, and have increased in ​weight per bushel: and it is now the opinion of some practical men, that the best bigg is very little inferior to barley for malting.

In malting barley, the loss in weight is from 21 to 22 per cent. Of this 14 consists of moisture, 1½ disappears during the steeping, 3 on the floors, 3 by commings or rootlets, and the waste 1½. As barley when thoroughly dried loses 6 per cent. of moisture, Professor Thomson considers the actual loss in malting as only 8 per cent.

The specific gravity of barley is from 1.280 to 1.333, that of malt 1.201.

From the interesting experiments of Messrs. Colin and Edwards upon the germination of different kinds of grain, it appears that when wheat, barley, French beans, or linseed, were immersed for a quarter of an hour in water at the temperature of 154° F., the power of germination was completely destroyed; and that water at 122° F. is the highest limit at which it is possible for barley to germinate after immersion.

It is very beneficial to kiln-dry the barley before malting. In the early part of the malting season, when the barley is damp, it cannot be made into good malt, unless thoroughly dried on the kiln. The grain absorbs moisture with greater avidity and regularity, and the process is facilitated. In good seasons, when barley is abundant, of good quality, and of a low price, brewers would find it ​very advantageous to lay in and kiln-dry a large stock, to be kept for malting the next season. By kiln-drying it will be kept perfectly sound, and will malt as freely or more so than new barley; and should the season prove unfavourable, such provision will be a considerable saving.

By the same valuable experiments of Messrs. Colin and Edwards upon the germination of different kinds of grain, we are led to suggest that the temperature used for drying the barley should not exceed 122° F., while in drying pale malt, the temperature is frequently as high as 160° or 170°. In the Records of General Science, vol. i. 445, Dr. Thomson states that very pale malt may be dried, although the temperature be brought as high as 175°.

The medium, however, through which the heat is communicated, modifies the range of temperature considerably. Thus the seeds before mentioned, if exposed to a temperature of 143° in air containing vapour, or of 167° in dry air, are deprived of their vegetating properties; and when wheat, oats, or barley, had been kept in sand at 113°, they would not germinate. Immersion in water at 167° for 14 seconds destroyed the power of germination. The grains of starch burst at a temperature of 167° according to Raspail.

In the Ann. de Chimie et de Phys. tom. v., Ann. Philos. xii. p. 201., Proust gives the following comparative analysis of barley and malt:

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These component parts, however, must differ considerably according to the different qualities of the barley from which the malt is made. Dr. Turner says, “the conditions necessary to vegetation are three-fold; namely, moisture, a certain temperature, and the presence of oxygen gas.” The necessity of moisture to this process has been proved by extensive observation. It is well known that the concurrence of other conditions cannot enable seeds to germinate, provided they are kept dry. That the presence of air is necessary to germination was demonstrated by several philosophers, such as Ray, Boyle, Boerhaave, and Muschenbroeck, before the chemical nature of the atmosphere was discovered. Achard afterwards demonstrated that seeds in general would not germinate without the presence of oxygen gas; and his experiments have been fully confirmed by subsequent observers. It has even been shewn by Humboldt, that a dilute solution of chlorine, owing to the tendency of that ​gas to decompose water and set oxygen at liberty, promotes the germination of seeds.

The late experiments of Saussure (1834) prove that in germination nitrogen is always absorbed.

The best barleys for malting are those called mellow in contradistinction to those which are hard or steely. The mellow barleys, generally speaking, are thin-skinned, and when the pickle is divided, either by the teeth or a pen-knife, the kernel is white and floury. The steely barley may also be thin-skinned, but when divided in the same way, the kernel has a bluish cast something like rice. This barley, although equally heavy, or even heavier than the other, will never produce such good malt, nor will the beer brewed from it have the same mellowness or richness of flavour as that produced from mellow malt.

Care should also be taken, that corn of different weights and from different soils, should be kept separate, so as that each different quality may be used alone. The heavier barley will generally require to be longer under water than the other, and when mixed will not grow equally on the floors, (an objection usually attending shipped or foreign barley), thus preventing the possibility of making fine malt. It will also be found, that cargoes of barley will never make such fine malt as that bought directly from the farmers. The reason is obvious—the different qualities cannot be kept separate.