Dr C. Graham is of opinion that, although the properties of the Burton well waters are very greatly due to the large quantity of sulphate of lime contained in them, the chlorides of sodium and calcium are also important constituents.
The yeast must be fresh and good; and all the vessels and utensils perfectly sweet and clean. If the latter be neglected, even the most skilful brewing will prove a failure.
Process of brewing:—
1. Mashing:—The ground or bruised malt placed in the mash-tun is macerated for some time in hot water, and the infusion (wort) drawn off from a hole in the bottom, over which a strainer or false bottom is placed, to prevent the malt passing out along with the liquor. During the process of mashing a peculiar principle contained in the malt, called diastase, reacts upon the starch with which it is associated, and converts it into grape-sugar. The more completely this conversion is effected the richer will be the resulting wort in sugar or “saccharine,” and the stronger and more alcoholic the beer produced by its fermentation. It is, therefore, a desideratum with the brewer to mash at the temperature which most fully promotes this important object. The best temperature for this purpose ranges between 150° and 170° Fahr. When more than one mash is made, the first should be something lower than the first-named temperature; the second may be from 175° to 185°; and the third as high as 200° Fahr.
If the first mashing has been rightly conducted, the whole of the starch will be converted into sugar, and the action of the second and third mashings is merely to wash out any of the remaining saccharine matter still existing in the crushed grain.
In practice, as soon as the water in the copper acquires the temperature of 170°, 45 galls. are run into the mash-tun, and 1 quarter of crushed malt gradually added to it. The whole is now thoroughly mixed with the mash liquor, by means of oars, or machinery, the agitation (mashing) being continued for 30 or 40 minutes, when 36 galls. more water from the copper are added, and the whole again well agitated, as before. The mash-tun is now closely covered up, and the mash allowed to repose for about two hours, in order that the diastase may exert its saccharifying power upon the unconverted starch of the malt. At the end of this time the tap is set, and the wort run into the ‘underback.’ It generally amounts to about 50 galls. The second mash is then made with about 60 galls. of water, at 185° F., and the whole process repeated as before. After an hour the liquor is drawn off, and the malt drained ready for the third mash. This time only 35 galls. of water are added at 200° F., and the whole is seldom allowed to stand longer than half an hour. It is then run off, and the malt allowed to drain as dry as possible.
In some cases the worts of the first and second mashes only are used for strong beer; that of the third mashing being kept for table beer, or as liquor to mash a fresh quantity of malt.
Pale malt and mixtures of malt and raw grain should be mashed for a longer time, and
at a somewhat lower temperature than brown or high-dried malt.
Instead of making second and third mashes as above described, it has long been the practice in Scotland, and is now becoming common in England, to sprinkle the surface of the grains in the mash-tun with water, at or about the temperature of 180° Fahr., by means of a simple revolving instrument termed a ‘sparger,’ and to let the liquor drain through the goods and run off by the tap with the last portions of the first wort. By this means the whole surface of the grain is continuously and regularly sprinkled with hot water.