BREWING, the manufacture of the alcoholic beverage beer, mainly from cereals (chiefly malted barley), hops and water. Though no doubt originally largely a domestic, and later a monas tic industry, brewing is to-day almost entirely in the hands of commercial firms. Until about the 12th or 13th centuries the preparation of beer on anything like a manufacturing scale appears to have been carried on in England mainly by the monasteries. As beer (q.v.) was in the middle ages the chief drink for breakfast, dinner and supper it must have developed into a great trade as the towns grew. Its importance in London may be gauged by the record of 30o brewers in the City and its liberties in 1419. Among the most cherished possessions at Brewers' Hall is the old book of the Brewers' Company containing its records from 1418 to 1440 and reputed to be the oldest company's book in existence. During the 15th century the spirit of craftsmanship was developing and in 1438 the Brewers, who were formerly the Guild of Our Lady and St. Thomas a Becket, were incorporated by letters patent as the Wardens and Commonalty of the Mystery of Brewers of the City of London. The brewery at Queen's college, Oxford, briefly de scribed later in this article, remains as an example of what these were several hundred years ago. Until the 18th century the wealthier classes generally brewed their own beer, but then it gradually became more usual to have it brewed for them at a reg ular brewery. This tendency to centralize brewing became contin ually more marked. The number of farmers who brewed for their own labourers and of publicans who brewed for sale diminished every year, the latter a great deal more rapidly as the tied-house system spread during the latter half of last century. In the year in England 8,863 licences were issued to brewers for sale, but by 1904-05 this number had been reduced to 5,164. Amalga mations and absorptions of the smaller public brewers by the larger concerns has gone on hand in hand with the extinction of the private brewers and is still going on. The number of licences for brewers for sale issued in 1914 was 3.746 and in 1927 (exclud ing Irish Free State) 1,722. Many of the present large firms in England were taking their shape and the names under which they are now known during the 18th century.
In the British Isles brewing is almost confined to top fermented malt beverages among which the India pale ales and strong ales of Burton-on-Trent, the stouts and porters of London and Dub lin, light bitter and mild ales are typical examples. The essential difference between pale, light bitter and mild ales lies in the flavour and colour which depend particularly on the type of malt and quantity of hops used in brewing them. Porter and stout differ from these in that a proportion of brown and black malt is used to give the black colour which is accompanied by a full, rich flavour. Beers of varying strength are brewed in each of the types mentioned, and some details of their composition are given in the article BEER.
In Continental Europe and America lager or bottom fermenta tion beer largely superseded the earlier "ales." Three characteris tically different types, the pale Pilsener, the medium Vienna and the dark Munich beers, typical of the three great brewing centres, soon stood out as examples which were followed and copied throughout the brewing world, though many developments were made in the original brewing processes, particularly in America.
All these beers are sold both in cask and bottle. A very great increase in the proportion bottled has occurred during recent years, and this has led to important developments in brewing and bottling processes.
Materials Used in Brewing.—The essential materials are water, malt and hops. The experiences of many centuries has shown that barley malt (q.v.) is the most suitable source of the extractives which supply the nutrient constituents of beer. The types of barley used for malting will be found described under MALT and BARLEY and it will be sufficient to mention here that brewers find it advisable to blend malts from barleys grown in different localities and countries. It is not often found possible to produce satisfactory light ale or beer from malted English bar ley only ; an admixture of grain from drier, sunnier climates is almost always advisable. A large proportion of such barley, grown in California, North Africa, Chili, Asia Minor and else where, is of the "six-rowed" varieties in contradistinction to the "two-rowed" varieties in which are comprised English malting bar leys and a great deal from the Continent. It is more husky than the European two-rowed barley and materially assists the drain age, which is an essential part of the mash-tun operations.
Malt of different characteristics and qualities is used according to the nature of the beer required. The "grist" for stout is made up of malt similar to that used in pale and mild ales blended with malt which has been more highly kilned or roasted in cylinders, or with roasted barley. Details of the methods used for produc ing the various types of malt are given in the articles on MALT and MALTING.
As the extractives of malt consist so largely of sugars and other carbohydrates produced by the conversion of the starch of the grain in the mash-tun, through the influence of "starch-convert ing" or "saccharifying" enzymes (q.v.) known as "diastase" also contained in the malt, their partial replacement in the wort by similar sugars obtained either from external sources, or actually in the mash-tun from unmalted cereals is reasonable. The use of such substitutes for malt is in large measure limited by the lack of malt flavour that their use in undue quantity would en tail, by the difficulty of converting an undue proportion of un malted cereal starch by the diastase of the malt with which it is mixed—the only permissible means of conversion; and the lack of soluble nitrogenous substances which are yielded by malt to the wort and which are necessary for the development of yeast and are among the essential constituents of beer.
Malt extract made from malt by a mashing process similar to that of the brewery, but designed to retain the enzymes of the malt in a condition of high activity, followed by evaporation to a syrup of the wort under reduced pressure, is sometimes used in the mash-tun or copper to provide additional diastase or yeast nutrients when either of these are lacking in the grist employed.
The unmalted grain substitutes, or malt adjuncts, most com monly used are maize grits, and flaked maize or rice with much smaller quantities of unmalted barley and oats. The maize is degermed in order to remove the oil, and then used as grits, or, after a special treatment comprising soaking, steaming and dry ing on steam heated rolls, as flakes. Rice is similarly flaked.
Oats are occasionally used as oatmeal or as oat malt in stout. In America much larger quantities of rice or maize were formerly used in some beers than is customary in England.
The sugars chiefly employed are cane sugar, invert sugar (q.v.) and glucose with lactose, or milk sugar, to a much smaller ex tent. The cane sugar is generally partially refined and selected for its luscious flavour. The glucose is manufactured by the con version of maize or other cereal starch and is generally com pletely converted, though partially converted products contain ing dextrin and maltose are also used.
Hops described elsewhere in a special article are used for the production of the aroma and bitter flavour, also on account of their dietetic qualities, and because they contain various preserva tive substances associated with the soft resins. The most im portant of these active principles are the bitter acids Humulon and Lupulon. They retard the rapid development of micro-organ isms which would turn beer sour or otherwise make it undrink able. Hops have also certain mechanical uses in the copper in which they are boiled with the wort. They help in the coagula tion of various colloidal protein substances and afterwards act as a filter bed in the hop-back for the removal of the coagulum previous to cooling and fermentation of the wort. The brewing value of hops therefore depends on their flavour-giving qualities, their preservative properties and the condition of the cones in regard to their compactness and unbroken state. Their colour and freedom from disease and foreign matter are also of im portance. The characteristic differences in flavour and preserva tive power between various varieties of British hops such as Goldings, Fuggles, Bramlings, etc. and, more particularly, be tween these and American and Continental hops make careful selection necessary and almost invariably a blend of several types is employed to secure the beer flavour desired. As the essential oils of hops, to which their aroma is due, are volatile and to a large extent dissipated during boiling in the copper, hop oil is extracted and sometimes added in small quantity to beer in con ditioning tanks to increase the hop aroma.
No other materials are used in the manufacture of beer than those mentioned, namely water, malt, hops, raw and prepared grain and sugar. The following substances used in the course of brewing can hardly be classed as brewing materials. Certain salts, particularly gypsum, are added to the water in small quantities to make up for deficiencies in the mineral constituents of the supply. Finings, made by dissolving isinglass in water acidulated with tartaric or sulphurous acid are used as a clarify ing agent. Caramel made from glucose or cane sugar by heating processes, is used in small quantities to adjust the colour of beer to that demanded by customers. The main source of colour in beer is the malt, and in the case of stout roasted malt or barley. The only preservative permitted in Great Britain is sulphur dioxide added in the form of sulphurous acid or its salts. The quantities permitted are fixed by the food laws of the different countries.
It was not until 1847 that the use of sugar was permitted in brewing in Great Britain. Previous to Oct. 188o duty was charged on the malt used, but by the Finance Act of that year, commonly known as Gladstone's Free Mash-tun Act, it was transferred to the wort produced and is now only charged on the malt under certain definite conditions referred to in the section on beer duty. One result of the transfer of the duty from the malt to the product was to enable brewers to make use of reason able substitutes. This freedom in the choice of materials has continued down to the present day, with the exception that the use of "saccharin," a coal tar product, was prohibited in 1888 on the ground that it gave an apparent palate to beer equal roughly to 4° in excess of its real gravity, the revenue suffering thereby. It has greatly helped brewers in the production of the light, bright and sparkling beers demanded to-day. Despite this, large quantities of beer and stout are made from malt and hops alone.
A fact that is frequently overlooked is that of the 11 million cwt. of malt used annually in Great Britain about 3 million cwt. is returned to the farmer as cattle food. This has a higher food value than the original barley due to the removal of starch by the brewer and consequent concentration of protein and fat in the grains. This food is of great value for milk production.
Brewing Waters.—The assurance of an adequate and suitable water supply, not only for brewing but : lso for cleansing and steam-raising purposes is among the first considerations in the establishment of a brewery. Unimpeachable purity is always de manded, and it has long been recognized that suitability for brewing depends on the nature of the saline constituents. Many well known brewing centres have become noted for particular types of beer and this can in some measure be ascribed to the water used. Typical analyses of waters from Burton-on-Trent and from Dublin indicate that brewing waters differ very widely. That from the wells of Burton-on-Trent is particularly hard, with a large amount of permanent hardness, while that from Dublin, and those from Munich and Pilsen, are comparatively soft.
Examination of the waters of Burton-on-Trent and Dublin would seem to indicate that hard gypseous water is most suitable for pale ales and beers, and soft water for dark beers and stout.
An explanation of the different results obtained by the use of different waters is found in the interaction of the salts dissolved in the water with certain of the constituents of malt, in particular in their effect on the natural slight acidity of the malt, which has an important bearing on the starch-converting and proteoclastic enzymes of the latter. Enzymes are very sensitive to the condi tions of temperature and also of reaction (acidity, neutrality or alkalinity) existing in the medium in which they occur. In the brewer's mash-tun these conditions are important factors in the influencing of the nature of products obtained from the malt and hence the character of the resulting beer. For each enzyme there is a range of reaction, usually a very slight acidity, within which it is most active. This acidity is not measured by the amount of alkali required to neutralize it, for a trace of a strong acid, such as sulphuric or hydrochloric acid, has a much greater effect than its equivalent of a weaker acid, such as acetic or lactic. It is measured by the extent to which the acid or, it may be, acid salt, is dissociated in solution, actually by the proportion of the hydrogen "ions" which it gives. This is called the "hydro gen ion" (q.v.) concentration of the solution and is denoted by the sign pH devised by Sorensen. The purest distilled water obtainable is dissociated to a very slight extent and has a hydrogen ion concentration denoted by pH= 7•07. This signifies neutrality. Increasing hydrogen ion concentrations are represented by pH values less than this, that, for instance, existing in a very dilute or Roo 00o normal solution of a strong mineral acid by pH= 5. Though real acidity is attributed to hydrogen ions these still exist in alkaline solutions, but in smaller concentration, represented by pH values greater than 7.
Though such slight acidities as are here dealt with are quite beyond our sense of taste they are of great importance in all reactions brought about by enzymes or micro-organisms, and, consequently, in the mash-tun and during fermentation. The optima for the starch converting and proteoclastic enzymes of malt are in the region of pH = 5 and it is found that the most satisfactory results are obtained in the mash-tun when the re action of the mash is about that represented by pH = 5 or 5.5• During fermentation there is a rise of acidity, and it is found that beer has a greater resistance to bacteria if its pH reaches about 4 than if its hydrogen ion concentration is less, the growth of the bacteria being hindered by the slight acidity while they thrive in media more closely approaching neutrality.
The saline constituents of the brewing water play a funda mental part in the attainment of the desired pH in the mash tun. The existence of any salts which would counteract the necessary acidity is harmful. Among such salts are the bicar bonates of calcium and magnesium. It is for this reason that these salts, which form temporary hardness in water, have always been removed from brewing liquor to a greater or less extent, generally by boiling previous to mashing, or more recently by partial neutralization. The effect of gypsum is best considered from the point of view of its reaction with certain important constituents of malt, namely the primary and secondary phos phates of which the former gives a large part of its acidity to malt, and the latter tends to produce too great an alkalinity in the wort. Gypsum converts the secondary phosphate to the primary or acid salt and in so doing increases the hydrogen ion concentration of the wort and brings it more closely towards the optimum for the activity of the enzymes. The result is a more complete extraction of the malt in the mash-tun and a greater conversion of the starch to fermentable sugars, with fuller proteolysis if the temperature is not too high. Alkaline salts have a reverse effect and restrict the conversion of starch and proteins. Other effects are produced by mineral constituents of the water apart from those due to hydrogen ion concentration. Sodium chloride, common salt, in small amount, may, for instance, tend to give a fuller flavour. The extraction of bitter substances from the hops may be increased or decreased. This effect on hop flavour is very marked with an alkaline water which would give a very harsh flavour with an amount of hops, or variety of hops, which would communicate a delicate bitter to a beer brewed with a gypseous water. It is also believed that certain of the salts present in water, magnesium sulphate, for instance, are requisite for the healthy development of yeast.
This brief description of some of the effects of the water used on the quality of the beer produced will indicate how very im portant this factor is in brewing. Brewers usually draw their supplies from wells or deep bores but many now use the drink ing supply of their district. When the water does not contain the saline constituents thought to be desirable for the type of beer produced, the lack is made up by the addition of gypsum and other salts. The necessity for a definite acidity in the mash-tun being recognized and failing its attainment by adjustment of liquor and materials, there appears to be no obvious reason why this adjustment should not be made in the mash-tun as an alternative to water treatment. This is a most delicate process as any excess of acidity is more harmful than the slight lack that may exist. It is, however, carried out with success in some breweries in Continental Europe and in many distilleries. The usual process is the production of a definite amount of lactic acid in a small portion of the mash by means of a lactic acid bac terium, Bacillus Delbriucki, and the subsequent addition of this soured mash to the main mash. Water treatment is, however, generally recognized as the simpler method.