The business of brewing is divided into two great branches : The manufacture of ale by the common brewers of Great Britain and Ireland ; and of porter, which is chiefly confined to the brewers of London. The method of'brewing ale in Scotland differs from that pursued in England so much, that, in order to give a practical detail of the process, it will be necessary to divide the subject into separate heads, to afford a distinct description of the operations, so that the methods of working may be clearly understood.
The difference of the English and Scotch methods of ale-brewing consists—1. In mashing, the English brewers run the water at a temperature of 170° Fahrenheit through the malt from the bottom of the mash-tun, and stir each mash. The Scotch brewers fill the maBh-tun with a sufficient quantity of water for the first mash, at a temperature of 175°, into which they run down the malt; they stir the first mash, preferring the use of oars to the mashing-ma-chine, which latter they think taints the wort. The succeeding mash is effected by sparging or sprinkling at 180°, which commences at the time the first mash is drawn by the taps; and this sparging goes on constantly until they obtain the full quantity of worts required for the brewing. 2. In boiling the worts, the English brewers, haying drawn a sufficient quantity of worts from the mash, boil down to strength generally about two or two and a-half hours. The Scotch draw a shorter quantity of worts, and boil down to strength generally in one hour and a-half. 3. In fermenting the worts. The English pitch at a high temperature, from 62° to 65°, and bring the gyle forward to cleanse into barrels within forty-eight hours. The Scotch ferment at a low temperature, from 50° to 55°, and work the gyle from eight to ten days, beating in the head of yeast occasionally, until the attenuation is judged completed, when they run the ale from beneath the yeast into barrels, where no more fermentation takes place. 4. The English brewers, in cleansing, mix the yeast on the head of the gyle with the wort, and run the whole brewing into barrels to cleanse; which is done by keeping them regularly filled up until the fermentation ceases, and as much yeast as possible separated from the ale. The Scotch cleanse in the gyle, as already described. In both methods of fermentation, which may be distinguished by the quick and slow method, the judicious brewers of both countries never wish to carry the degree of heat more than ten de^ grees higher than that at which the wort has been set to fermentation.
It will thus be readily perceived, that, to give a practical detail of both processes of brewing, the object will be much better accomplished by carrying through a description of a single brewing of ale by each of these methods. Before doing so, it may not be unacceptable to take some notice of matters connected with both modes of brewing, and of such previous steps, on preparing and judging of materials, as may be thought conducive towards producing ales of the finest flavour and quality.
The first question that occurs, and indeed such a question has often been asked, since so much difference exists in the methods of brewing Scotch and English ales, by which mode can that of the finest quality be produced \ The question is of considerable importance, and, in fact, is one of difficulty to answer. With common brewers, local prejudice and taste must be so much studied, that in most places it is hazardous for them to alter their established system. In large towns this may be got over, where the advantage of improvement is so decided and the sale quick, that the change in the system of brewing cannot affect the regular production sent out. The adoption of the Scotch system by brewers, in such circumstances, may be very advantageous; but to small provincial brewers, who brew perhaps to the extent of 20 barrels two or three times per week, the adoption of the Scotch system presents so many difficulties, that its introduction into England, to any great extent, is dubious.
To the intelligent brewer, whose eye meets the sketch already given of the difference in the methods of brewing, it must at once be obvious that the chief point lies in the fermentation of the worts. Now, in many parts of England, brewers mash two or three times weekly almost all the year round. Were such to adopt the Scotch mode of brewing, they must have eight or nine gyles constantly in operation. The danger of so large a stock running into the second fermentation during the summer months presents a formidable objection. There ajre parts, however, of the Edinburgh mode of brewing ale, which may be profitably adopted in England, without, in any degree, deranging their usual methods of working, such as the method of sparging the mash, and in shortening the time of boiling the worts; a judicious application of these parts of the Scotch method to the quick system of fermentation, would be of importance both towards economy, and improving the quality of the ale.
The Edinburgh system of brewing is decidedly the best that can be adopted, when the ale is intended to be bottled and kept for any time without the addition of hops ; but when intended for draught, and when the run is constant, and the demand instantr ly to be supplied from the brewery all the year, the English system is greatly preferable ; so much so, indeed, that some of the Edinburgh brewers have rather followed the English method in brewing their ales to be drawn from the butt, and have found the alteration of much advantage. It will be admitted, therefore, that both methods possess superior points to each other, and that to a brewer who studies improvement, a knowledge of both systems in practice may become valuable, according to the circumstances in which he may be placed.
The beBt ale produced in Great Britain is that which is brewed by private families in England. With such, home-brewed is made and kept in a state of perfection which ale of no other country can equal.
When the best malt and hops are selected, the first mash drawn of sufficient strength, and the second mash so regulated as to make up the quantity of worts required for the brewing, the boiling of the worts with the hops only continued so long as necessary to extract their aromatic bitter, and the fermentation managed with judgment, ale is produced approaching to wine in quality, which may be kept in fine condition and pure flavour for years. This home-brewed is always made by the process of stirring the mashes, and of quick fermentation, so that it is quite evident that the superiority of one ale to another is not to be attributed either to mashing or fermentation. One thing is certain, however, that both in Scotland and in England, ales of inferior quality are produced, even where the best materials are within reach of the brewer. This ought never to arise where fine malt and hops are employed; but in brewing as in other arts,'want of skill and judgment make a wreck of the best materials.
Still, it is undeniable, that a marked difference exists in the quality of ale made in the same locali-
o ties, where the brewers use equal quantities of malt and hops, the same kind of water, and work out the process by similar methods. In London and Edinburgh, where the best materials are in the choice of brewers, with a quick sale and consumpt of the production, with a large amount of capital, and where every means of improvement have been keenly studied, and, when practicable, adopted, it is not surprising that a superior quality of liquor should be made* to that produced by provincial brewers; but even in London and Edinburgh, the qualities of the production of brewers differ so much as to be distinguished by the consumer. It is not unimportant, to the practical brewer to investigate the cause of this difference. The process of brewing admits of different methods of working, and there are few brewers but have some secret with regard to heats of mashing or fermentation, by which they conduct their operations. The distinctive character of a brewer's ale may, therefore, be accounted for by his observing , the same unvarying method throughout the whole process of his manufacture, using the same proportions of materials, and drawing the supply of water from the same source. There are many important truths, however, in brewing malted liquors, which, being discovered incidentally, are regarded by the practitioner as secrets. Hence the many pretended discoveries which appear in the works on brewing during the course of last century, and which have disappeared before the truths of scientific investiga-
tion. Properly speaking, there are no secrets in brewing, either for the production of alcohol or malted liquors. Should a practical brewer possess knowledge on any particular part of the processes of these arts, he may perhaps treasure it as a secret, and imr agine that he alone is reaping the advantage of the discovery, while others have, in all probability, acquired the same knowledge from observation or practical experience, and are in the constant practice of acting upon it like himself, and of believing, like him, that they are the sole possessors of the secret.
In brewing, there are many methods of working out the various processes, and brewers differ muoh in practice in conducting their operations; but the theories now established by scientific demonstration, incontestibly prove that it is only by working as closely as possible to the principles of chemical science, that .the best and most profitable result can be produced, whether affecting the strength, or flavour, or preservation, of the various productions of malted barley. By a knowledge of chemical science, I mean that general knowledge of chemistry which any person of common education may acquire who wishes to improve himself in his profession, and which, to a brewer or distiller, is of the greatest value. With this knowledge, the process of brewing, whether for distillation or making ale, appears in a new light. The brewer works with confidence, and oo difficulty occurs in the processes for which he is not prepared with a remedy. From the time of laying on the first mash, and obtaining the worts of a known quantity and strength, he is enabled to regulate the whole future process, so as to preserve the advantage acquired from working with fine malt, and obtain that richness of flavour which distinguishes malt liquors, when skilfully and judiciously made. But there is another advantage. This knowledge enables him to carry economy through the whole process from beginning to end;—a most important matter in brewing, where so much waste occurs.
There are a few points in malting and brewing which may be brought under the notice of the reader, and upon which the successful production of ales of the best quality much depend.
1. In malting, after the process of artificial germination has been carried to that particular stage sufficient to secure the greatest outcome of starch, to kiln-dry the malt by regularly increasing heat, from 100° to 150°. When the kiln-heat is too low at first, the malt renews its growth, and begins to spring; when too high it will blow or expand, and when the heat is then rapidly increased get scorched. Much depends on kiln-drying; and brewers who have maltings cannot give too much attention to this branch of their business, nor to the next point, which is to regulate their making of malt by the quantity they employ in brewing, so as to contrive always to work with as fresh-made malt as possible. With fine, recent made malt, hops of good quality, and common care and skill in conducting the process of brewing, ales of the richest flavour are sure to be the result. 2. In mashing, to regulate the mash by heats suitable to the age and quality of the malt in operation, and the state to which it is crushed or ground. 3. Never to draw the second mash to a greater length than can be boiled down to strength within that particular time necessary to cut the worts; and secure to the brewing the fine aromatic bitter principle of the hops. 4« In fermentation, if by the slow method, to regulate the heat of the gyle with such precision that the attenuations and increasing heat of the worts should be commensurate, slow, and progressive. This is accomplished by the use of the refrigeratory tube or worm, with which every gyle ought to be fitted up ; and if by the quick method, to watch the favourable time for beating in the yeast, the cleansing not to be too hurried, but the worts allowed full time to strengthen the yeast before it slackens; and in both methods, to work the gyle so as not to allow the worts to rise more than 10° or 11° of heat higher than when first pitched. 5. Cleansing. The fermentation of the worts, either by the quick or slow method;—their attenuation, or, in other words, the partial resolution of the starch-sugar of the malt into alcohol;—and the preparation or cleansing of the yeast from the liquor,—are all processes which require the brewer's skill and experience to bring to a successful result. By the slow method of fermentation, the ale is cleansed in the gyle, and when all is right, and the attenuation brought .dbwn to the point desired, it is run into the same casks which are sent out to^the customer. Little or no more fermentation takes place, and ale is never racked into other casks by the Edinburgh brewers ; but in Alloa, Stirling, and Perth, which are the best districts for brewing ale next to Edinburgh, they run the finished ale into butts, and afterwards rack into barrels, as orders are executed. These two methods of cleansing the gyle, in the Scotch system of brewing» are particularly worthy of the notice of the reader: both methods are the best suitable to the respective localities. The Edinburgh brewers pursue their method because their ale is sent out at once to the customers' cellars. The Alloa district brew large quantities, which are sent to Glasgow, and other parts, generally for immediate use. In racking, the Alloa brewers prepare what they term fillings, which are worts of the same brewing, set at the quick fermentation heat, 60° or 62°, and use part of this store in racking, putting an English pint into each barrel. The Edinburgh brewers rely on the fine condition of their ale, and add nothing whatever before sending out the stock. I have been thus particular, that English brewers may understand precisely the two methods of finishing the gyle by the Scotch system. Brewers sometimes overturn it into a clean tun or square, to check too rapid fermentation and cool the whole brewing, or to prepare for exportation; but for home consumpt, the two methods above described are adopted. In cleansing by quick fermentation or the English method, one point may be particularly brought to notice, that is, when the working of the wort in the barrels has nearly ceased, to fill and keep them filled up, with ale of the same brewing, from a barrel which has been regularly worked forward with the rest, and not to draw the troughs or plus-tub too close, for the sake of getting as much wort scra)>ed together as finish the filling up of the barrels. Many brewers pay n attention to this necessary precaution, but many do not; and whatever is useful in brewery practice should be put on record.
In such a complicated process as brewing, of course there are many different opinions as to the best methods of carrying on the operation, but the whole art resolves into this:—From a given quantity of malt and hops required the greatest possible quantity of ale of equal strength» and of the finest flavour. One man may produce twenty hogsheads of ale of excellent quality from a given quantity of malt and hops, and be esteemed accordingly; but he who can produce twenty-one hogsheads of as good ale from the same quantity and quality of materials must be regarded as much more successful.
Since the beginning of the present eentury, great progress has been made by practical chemists, who have turned their attention to investigating this most difficult art, both on the Continent and in this country. Their valuable researches have placed it on the ra tional foundation of science. Tfie true theories of the whole process is wellnigh established ; and practical brewers may, with common industry and research, very readily give a good reason for every part of the process. The art of varying the operations of brewing, so as to produce ale of distinctive character, such as Edinburgh or English home-brewed, or common ale, must be of advantage to every practical brewer. I shall therefore carry through a description of 'making twenty barrels of ale from eighty bushels of malt, and eighty pounds of hops, and continue the same proportion in both methods of brewing, as practised in Scotland and England, with such information connected with the various processes as may be reckoned useful.
In the present preliminary remarks, I shall not take up time in describing the utensils used in brewing, as these will be noticed during the description of the operations. It may be shortly stated, however, that the copper is built so high as to command all the other utensils of the brewery. The mash-tun is placed as near it as convenient, and beneath is the underback, large enough to contain the whole worts of the mash. In every brewery of magnitude, there are several boilers for boiling the worts together, or separately, and preparing, water for all other purposes. When all the utensils are judiciously placed, and are in good proportion to each other, it is almost unnecessary to say that the working of the brewery is rendered more easy and economical, and the various processes are carried on with greater ease and satisfaction.
The capacity or size of the utensils should always exceed the calculated quantity of beer they are intended to make. A boiler to brew 20 barrels of ale, should be large enough to hold from 35 to 40 barrels of water: it requires all that capacity to hold the worts drawn from the mash, and which must be so reduced by evaporation, in boiling and cooling down to strength. The boilers employed to boil the worts ought to regulate the size of all the other utensils. Fanners are sometimes placed over the coolers to assist in cooling the wort. Where the roof of the cooling-room is low, or the situation confined, fanners are of necessity advantageous; but where it is high, and the apartment spacious, with the windows sufficiently open, they are prejudicial. They must be considered to supply a defect in the construction of the cooling-room, because they disturb the worts in the process of depositing the coagulated fecula, and other vegetable sediment, which, when retained, helps on the acetous fermentation afterwards. I know very well that some intelligent brewers are of opinion, that the worts get rid of this sediment or precipitated fecula during the process of 4he vinous fermentation, and adduce the practice of the distillers, who run these vegetable remains into their gyles to increase their attenuation ; but I
have ever found, that the purer I got the wort cooled p down and pitched, the better and purer Was the ale ; and that where fanners were used, the damage they occasioned was greater than the risk of time lost in cooling by atmospheric influence alone.
The process of malting is well known, and has been often described; but it may be remarked, that as the artificial germination of barley, and kiln-drying to stop that growth, which makes it into malt, is often part of the brewer's business, he ought, at the commencement of each brewing, to be a judge of the malt in operation to regulate his future proceeding. It is a mistake of some writers who have stated, that the hordein or starch of barley is converted into sugar by the process of malting ; neither is it correct to say that this process either destroys vegetable life or effects achange in its constituent principles; the only change that takes place is, that barley, during the process of artificial germination, loses part of its gluten and mucilage, which are taken up by the rootlets and acrospire, with a small portion of sugar, which is developed at the same time as nourishment for these parts of the corn.
Malt, when crushed or coarsely ground, and treated with twice its weight of water at a temperature of 160° to 180°, and allowed to digest or infuse for two or three hours, is converted into glucosin or starch-sugar, and held in solution. This is simply the process of mashing to make strong ale.
In preparing malt, therefore, to undergo this pro cess, the brewer must judge from its appearance in colour and quality, how far it may be most profitable to grind it rough or small, to obtain the strongest wort. During the course of the yeai*, he may hare various qualities to operate with, and it requires skill and judgment to manage this part of his business. Recent made malt requires care in grinding. When of fine quality, the rollers of the mill should be slackened a little, not to crush it too fine. Malt of this description always yields worts of the richest flavour. When old, pale malt ought never to be ground small, nor mashed at a high temperature. It is liable partially to set, and yield turbid wort. Amber and brown malt bear a high temperature in mashing, 185° to 190°; but it is neither safe nor prudent to go beyond 185° with any malt whatever in the first mash. With average malt of all descriptions, 175° is the best and safest heat that can be used. High heats in mashing certainly produce the strongest, but not the finest worts. When ales are brewed by mashing at a high temperature of water, vegetable extract comes over with the starch-sugar, and, not being got rid of during the succeeding processes of boiling and fermentation, remains in solution in the finished ale, and disposes it prematurely to assume the acetous state. In all cases when the brewer has the control of these matters, experience must be his guide.
Of hops to be used in the manufacture of ale, every brewer may be held to be a judge. But the use of them in boiling the wort, \he nature of the bitters they impart, and the best method of extracting the essential aroma of the plant are very different matters, and merit particular investigation by those whose aim is to make ales of very fine quality. Next to their choice, is their preservation. Fine Kent hops are sometimes bought, and, on arrival at the brewery, conveyed to the loft, and kept until worked up. If kept in stock for any great length of time they get winded, and lose all their most valuable properties. Now, when hops first arrive at the brewery, each pocket or bag should be subjected to the screw-frame pressure, which compresses it to two-thirds oi its size; it is then corded, and the hops will keep all the season sound and fresh. For the methods of extracting the aroma and bitter principles, I must refer to the proper place in the order of brewing.
Much of the fine condition and keeping quality of malted liquors depends on the water with which they are made. Brewers who are scantily supplied, or have occasion, as scarcity or drought occur, to use water inferior to that which they commonly work with, cannot be too much on their guard in this respect. In some instances I have observed brewers and victuallers, both in Scotland and England, using brackish water supplied by wells on their own premises, or from some neighbouring rivulet, which contained too much vegetable remains, in both cases injuring the fermentation and damaging their ales, where springs of pure water were not far distant.
In these cases the expense of bringing such into the work must be compared with the prospective benefit to be derived from their use, and guide decision ; for, both in malting and brewing, it is of the greatest importance to possess a constant supply of the beat water. Pure soft spring water, such as rises from chalk or limestone formations, is the best. River water that flows in a hilly district, is also generally good; when its course is through moss or level districts of country, it holds vegetable remains in solution, and the yeast takes a character from its use as well as the extract from the malt. Ale made with it is always soft, rarely in very good condition, and apt to be readily influenced by atmospheric change and run into acidity.
The choice of materials is in the power of every v brewer. The preparatory steps to be taken in bringing them into operation to the best advantage, and in carrying through the various processes with skill and economy, so as to secure a production of the best possible quality commensurate with the quantity of material employed, must now engage his attention.
* The whole art of brewing ale is comprehended in the six following divisions: 1. Malting, and preparation of malt r 2. Mashing ; 3. Boiling ; 4. Cooling ; 5. Fermentation ; 6. Cleansing. Storing and management of vats, and racking and mixing of stock for delivery, may be reckoned another division ; but the six enumerated combine the art of making ale and bringing it forward to its first finished state. A
brewer, to be proficient in his business, must examine each of these processes by itself; he must study each in all its bearings, and endeavour to find out a reason, founded on sound principles, for the action of the matter before him, for the cause of that action, and for the successive changes which are produced on the malt and water by the agency of caloric, as he combines one part of the process with the next, until the whole experiment is successfully carried through to the desired result.
The investigations into the various processes of malting and brewing by Dr Thomson of Glasgow have led to a better knowledge of these arts, which it may be necessary shortly to notice.
During the course of last century, from the time that the art of manufacturing strong beer and ale underwent a decided change by the gradual substitution of porter in London for public consumpt, there are no authors whose works can be referred to as affording any thing like a rational theory of the art of brewing malted liquors. Chemists had not yet advanced so far in analytical research, as to investigate the intricacies of the decomposition of barley,—to follow up the action of caloric on'its constituent substances,—to discover the principle of fermentation, and to illustrate the formation of sugar, carbonic acid, and alcohol, by demonstrative experiment. At a very early period, Mr Combrune, a London brewer, found out that in the mashing process malt had the property of taking in water at a high degree of temperature, in proportion to its high dried colour, and resolving into sugar without setting, or being converted into glutinous paste; and although his experiments in the drying of malt, and the colour which it assumes by exposure to certain degrees of heat, have been proved by Dr Thomson to be altogether erroneous, arising from the improper manner of conducting his experiments, it cannot be doubted, that his writings had for many years a decided influence on the practice of English brewing.
Towards the latter end of the century, Mr Richardson, a brewer of Hull, constructed the first saccha-rometer, by weighing a barrel of water and converting it into malt wort. By weighing it again, he ascertained the weight of saccliarum held in solution. The idea was ingenious, but, like Mr Combrune's experiment, was not founded on correct principle. This subject, now become of infinite importance to distillers and brewers, fell also under the investigation of Dr Thomson about the year 1805, who discovered that the capacity of water to hold sugar in solution differed at different degrees of heat; and that to construct a saccharometer on a true principle of science, it was necessary, using his own words, " to dissolve determinate weights of the solid extract of malt in given quantities of water." Dr Thomson afterwards constructed the saccharometer, now so well known as Allan's, the name of the instrument-maker in Edinburgh who manufactured it. " It indicates the specific gravity of the wort, from which, by means of a sliding rule, which accompanies the instrument, the weight of saccharine matter contained in it is at once determined."
The utility of this instrument is now universally appreciated. With this invaluable guide, the brewer is enabled to work out his process with confidence. Whatever may be his knowledge derived from experience, this checks all erroneous calculation, and always proves the present weight of saccharum in hand,—a most important point in brewing economy.
Dr Thomson had made numerous experiments on barley, malted and unmalted; and during these investigations, he discovered the law, that malt preserves its pale colour on the kiln at a very high temperature, in proportion as the heat is gradually increased ; a most important discovery, because it follows, that this high-dried^ pale malt will stand a higher mashing heat, and afford a stronger and richer extract, besides turning out a better keeping malt than that kiln-dried at a lower temperature.
Mr Combrune's rule, that the heat of the water in mashing ought to be regulated by the colour of the malt, and, therefore, that the paler the malt, the lower ought to be the temperature of the mashing water, and the browner the colour, the higher temperature it will bear without setting, should thus be taken with reservation. It is only true when the malt has been properly kiln-dried, and when heat, at a very high temperature, judiciously applied, is the cause of the colour of the malt. Mr Combrune's experiments on the heats at which it changed colour from pale to brown and black, were founded in error. They were not conducted on a maltster's kiln, but, as Dr Thomson observes, by placing a sample of undried malt in an earthen pan, and setting it in a stove, and, by stirring it as the malt deepened in colour, ascertaining its increased heat by the thermometer, the malt at the bottom of the jar next the fire probably being exposed to 200° or 300° of heat.
The experiments of Dr Thomson not only proved the fallacy of Mr Combrune's conclusions; but they brought out the valuable truth—that malt has the capacity of bearing a very high temperature on the' kiln, without losing either its pale colour or the power of germination. When the heat is gradually increased from 100°, it may be raised to 175°, without loss of colour, and with a capacity of bearing a high degree of heat in the process of mashing, without setting the mash.
Pale malt, dried at a high temperature, keeps a much longer time, without imbibing so much moisture as to injure the future extract, than when dried at the heats which maltsters generally employ; and it will invariably be found, that when dried by this law of Dr Thomson, the saccharine extract will not only be of greater weight, but of finer flavour, than when dried at low temperature, and preserve its qualities for a much longer time when kept in stock.
Very great care, however, is necessary, in kiln-
drying malt at a high temperature* to preserve its colour and mellowness. It most be gradually brought up from 90° or 100°, with this especial observance, that the kiln requires to be previously tempered to these heats before the malt is spread on its floor. The malt being turned after it has been on the kiln two or three hours, the heat is gradually raised to 120°. During this increase of heat it is turned again, and the temperature gradually raised to 140° and 150°; now precisely at this period it may be continued and finished on the kiln, as is the present general practice, or the heat may be increased further up to 170° or 175°, according to Dr Thomson's law, the maltster watching its colour, and trying its condition. It must be pale and mellow, the ends of the grain not having the least appearance of being dried brown, or scorched, and having preserved this condition at these increased heats, the furnace or firegrate is drawn, and the kiln is finished, by allowing the malt to remain on the floor until the comings (rootlets) are trodden or screened off before removing it into stock.
The third investigation is the theory of fermentation ; a subject so important and valuable to brewers and distillers, as leading them in safety to the practical methods of securing the best fermentation in their respective processes of brewing and distillation.
It is evident that the theory of fermentation could only be established by the knowledge of the consti tuent principles of sugar by chemical analysis. During the eighteenth century, chemical science had not advanced so far as to enable the best chemists to be equal to the task* Lavoisier was the first who attempted the solution of this intricate investigation; and he was followed by the most distinguished philosophers in Europe who turned their attention to the subject. Dr Thomson, having examined and combined the various experiments of these eminent chemists with his own researches on the subject, has arrived at the important conclusion, that glucosin, or the sugar of starch, is resolved, by decomposition, into equal parts of alcohol and carbonic acid.
The fermentation, therefore, of malt wort is the action which accompanies its resolution into these substances. It is necessarily either spontaneous or artificial. It is yell known, that when wort or any other solution of sugar, at a temperature above 70°, is allowed ta remain in a warm atmosphere, it begins spontaneously the process of fermentation; and that when treated with a proportion of fresh yeast, this process immediately commences. But yeast cannot be said to be the fermenting principle. Yeast is a combination of various substances derived from malt, which are agglutinated and separate from the pure wort during fermentation. Dr Thomson has shewn that none of the substances which compose yeast has the power of commencing fermentation; and comes to the only conclusion that can, perhaps, ever possibly be arrived at,—that it is sugar in a state of partial decomposition that acts as the fermenting principle, and which is brought over from the wort along with the other substances contained in yeast. Intelligent brewers will instantly corroborate this important fact. They know when fresh wort is thrown upon yeast, and stirred together, how strongly and rapidly it springs into fermentation, and how useful it is in bringing forward the languid gyle; and that when the head of yeast on the gyle-tun is beat in, and sent down, holding sugar in partial decomposition, to react on the worts beneath, how effectually the process is renewed. The same principle works in the English method of cleansing, when the barrels are kept regularly filled up with half-fermented worts, until the yeast assumes the agglutinated form, and separates from the ale altogether.
The repeated doses of fresh yeast which distillers are obliged to use to work down their worts to as great attenuation as possible, also prove that sugar, in a partial state of decomposition, is the true fermenting principle, and that it is only by viewing it in this light that any approximation can be made in forming an estimate of the equivalent values of different yeast in the process of fermentation.
The investigations of Dr Thomson are so important, that they may be justly placed before the reader as the foundation of many improvements in the art of brewing.
1. That the capacity of water to hold sugar in so lution differs at different degrees of temperature, and that the specific gravity of malt wort can only be proved by dissolving determinate quantities of the solid saccharine extract of malt in given quantities of water.*
2. That malt at a high temperature, in kiln-drying, maintains its pale colour and quality of producing the richest ale-worts, in proportion as the heat is gradually raised; and that in proportion to the high temperature at which it is dried, it bears a high degree of heat in the process of mashing without setting the goods.
3. That the theory of fermentation is resolved by the decomposition of sugar into equal parts of alcohol and carbonicuacid ; and that the principle of fermentation in yeast is sugar in a state of partial decomposition.
I shall conclude this chapter with some observations on the proportion of materials, and degrees of heat, used in the processes of brewing. These observations of facts, made in the course of practical experience, may afford the reader a general knowledge of the art; and, taken in connection with Dr Thomson's investigations, already explained, draw the attention of brewers and distillers to such parts of the
* This discovery was immediately followed by the construction of the saccharometer on correct principles, which was made under Dr Thomson's directions, by Mr Allan, a mathematical instrument-maker, Edinburgh.
process as, in the present methods of working, admit of improvement.
Rules, Proportions of Materials, and Heats used in the Process of Brewing Malt Liquors.
1. Barley, when dried on the kiln, possesses the same constituent principles as when artificially germinated, and converted into malt. In either state, when crushed or ground, and treated with water raised to the temperature of 150° for raw grain, and 175° for malt, and allowed to digest three hours, the starch they eon tain is changed into glucosin or starch-sugar.
2. The quantity of water employed for the first mash may be averaged as twice the weight of the malt. The quantity for the second and third mash is proportioned to the required strength of the ale, and the time and 'manner of boiling and cooling the worts.
3. The capacity of malt to retain the wort of the first mash is 28 gallons for every quarter of malt in operation. This capacity decreases in proportion to the increase of pressure from increased quantities of malt in operation.
4. Boiling the worts combines four actions, which affect the saccharine extract. (1.) The process of boiling, which cuts the wort, and coagulates part of the starch of the malt, and other vegetable matter which comes over in solution from the mash. (2.) Condensation, the amount of the weight of which is equal to what was contained in the wort driven off by evaporation. (3.) Escape of the wort by evaporation. (4.) Destruction of part of the saccharine extract by evaporation during the time of boiling.
5. One and a-half hour's rapid boiling is sufficient for any wort whatever. The additional time of boiling being necessary only to condense the worts to a required weight of sacch&rine extract, called boiling down to strength.
6.' Worts boil down in an open boiler 5 lbs. saccharine extract per barrel in one hour, when their weight, as indicated by Dr Thomson's saccharometer, is 50 lbs. per barrel ; and this rate increases one to ten every hour they are subjected to the boiling temperature. Thus worts of 60 lbs. per barrel, boil down 6 lbs. per hour ; 70 lbs. per barrel, 7 lbs. per hour ; and so on in regular proportion, up to the greatest weight saccharine extract is obtained for making ales.
7. Hops give out, first, their fine aromatic bitter principle; and, second, their empyreumatic bitter, in proportion to the time and manner of boiling the wort.
8. Hops take up four times their weight of wort ; but this capacity to retain worts diminishes in proportion to the length of time of boiling.
9. Worts, from the time of being spread on the coolers at a boiling temperature, until cooled down to
60°, lose one-eighth part of their bulk by evaporation, and condense in proportion to the quantity of water driven off,—deducting that portion of saccha-rum which escapes during evaporation. This amount of condensation on the coolers, added to that which takes place in boiling, may be calculated by the brewer when he first ascertains the quantity of worts he has obtained from the mash, and their weight, as indicated by the saccharometer. By such a calculation he is enabled to shorten or vary his future process, so as to take advantage of the superior strength of the mash from working fine malt, and increase his production of ale in proportion.
10. Attenuation, or resolution of brewer's wort into alcohol, when carried a certain length, decreases in proportion to the strength of the wort. As the carbonic acid escapes, by the process of fermentation, the alcohol increases, until it acquires strength gradually to destroy the fermenting principle. In strong wort for ale, this attenuation must be carried down according to its weight of saccharum. When the worts range from 90 to 120 lbs. per barrel, the attenuation may be regulated with precision. When they range from 60 to 90 lbs. for weaker ales, the attenuation increases in proportion to the weakness of the wort, and is apt to work down more than the brewer desires. Weak ales, over-attenu-ated, lose in value, and are injured in ^proportion to the saccharum taken up, which ought to have been left in sufficient quantity to give a fulness of taste to the ale in consumpt.
11. In pitching the worts, or setting them to yeast, 52i° is the mean heat for the slow method of fermentation, with an increase of 10° for the process of attenuation; 62£° is the mean for the quick method, with an increase of 10° for being finished in the gyle; 7i per cent, of the worts may be calculated as the quantity taken up by the formation of yeast, and loss and waste by the slow, and 10 per cent, by the quick, method of fermentation. In the slow method, one gallon of yeast to four barrels of wort, and in the quick method, two gallons of yeast to five barrels of worts are good proportions to form the onset. In summer, a third less in the slow method is sufficient for the purpose; in the quick method, the same proportion is nearly preserved throughout the year.
12. Maodmum Extract of Starch-Sugar from Malt.—As this is a question of very great importance to brewers, and as no arbitrary rule can possibly be laid down on the subject, I shall endeavour, in a concise and explicit manner, to offer a few remarks founded on practical experience.
It is evident that the productiveness of malt in yielding saccharine matter, depends on the quality of the barley from which it is made, and on the skill by which it has been artificially germinated and dried on the kiln. About this there cannot be any dispute ; and there is no occasion whatever for
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