CHAPTER I. On the Intimate Relation existing between the Deterioration of Beer, or the Wort from which it is Made, and the Process of Brewing.

At the outset of these “Studies,” let us briefly consider the nature of beer and the methods of its manufacture.

Beer is a beverage which has been known from the earliest times. It may be described as an infusion of germinated barley and hops, which has been caused to ferment after having been cooled, and which, by means of “settling” and racking, has ultimately been brought to a high state of clarification. It is an alcoholic beverage, vegetable in its origin—a barley wine, as it is sometimes rightly termed.^[1]

Beer and wine, however, differ widely in their composition. Beer is less acid and less alcoholic than wine; it holds more ingredients in solution, and the nature of these ingredients is by no means similar to that of those which are found in wine.

These differences in the component parts of wine and beer give rise to corresponding differences in the keeping qualities of the two liquids. The small amount of acidity in beer, its poverty in alcohol, and the presence of matter that is saccharine, or liable to become so, all operate in imparting to beer a tendency to change, which wine does not possess. That this unequal resistance to the aggression of diseases is due to such differences, may be proved by the fact that wine could be made much more liable to change than it actually is, by a diminution of its acidity and its usual proportion of alcohol, or by increasing the proportion of viscid or saccharine matters,^[2] modifications which would tend to assimilate its composition to that of beer.

We have remarked elsewhere that the pains devoted to the rearing of vines, and to the ordinary operations of vinification, such as ouillage,^[3] sulphuring, and repeated rackings, as well as the use of cellars and vessels hermetically closed, are entailed by the necessity of counteracting and preventing the diseases to which wine is liable. The same may be said, a fortiori, of beer, inasmuch as it is more liable to change than wine. Manufacturers and retailers of this beverage have to strive constantly with the difficulty of preserving it, or the wort used in its manufacture. We may readily be convinced of this by reviewing the usual processes of the art of brewing.

When the infusion of malt and hops, which is termed wort, is completed, it is left to cool. It is next put into one or more casks or vats, in which it is made to undergo alcoholic fermentation—the most important of all the processes in brewing.

The cooling must be as rapid as possible. This is a condition of success; otherwise, the wort may deteriorate, which will necessarily lead to deterioration in the quality of the beer. As long as the wort is at a high temperature it will remain sound; when under 70° C. (158° F.), and particularly when at a temperature of from 25° C. to 35° C. (77° F. to 95° F), it will be quickly invaded by lactic and butyric ferments. Rapidity in cooling is so essential that to secure it recourse is had to special apparatus.^[4] Even in the preparation of wort, especially when it is effected by successive mashings, in summer, deterioration is imminent: in fact, it is not rare to see the wort becoming acid during the mashes, if these are not accomplished with all possible celerity.

After the wort has been cooled, it is mixed with yeast. This is obtained from a previous fermentation, and, after being thoroughly pressed, is added at the rate of from one to two thousandth parts of the weight of the wort, that is, from 100 to 200 grammes per hectolitre (about 4 oz. to 8 oz. average for every 25 gallons). At first sight, this yeast seems free from the possible diseases of the wort and beer; but this is by no means the case.

Now, why do we add yeast to our wort? This practice is unknown in the art of vinification. The must is always left to spontaneous fermentation. Why should we not leave the wort to operate in the same manner?

It would be a mistake to suppose that in the brewing of beer yeast is added with the sole object of accelerating fermentation, and making it more rapid. Rapidity in fermentation is a very questionable advantage, and one which is not desired by brewers, who rather agree in pronouncing it injurious to the quality of beer. It is in the easy deterioration of the wort, or what is tantamount to it, in the facility it affords to various spontaneous fermentations, that we find an answer to these questions. The must, through its acidity, due to the presence of bitartrate of potash—which seems to promote alcoholic fermentation—through its proportion of sugar, and perhaps in consequence of some other peculiarity of its composition, always undergoes regular alcoholic fermentation. The diseases of wine, at the commencement of its manufacture, show themselves, so to say, in a latent state only. Therefore a vintage can be left, without inconvenience, to spontaneous fermentation.

With wort the case is quite different. Under certain accidental circumstances it is possible that alcoholic fermentation alone may take place in a wort left to ferment spontaneously, and the quality of the beer remain unimpaired, but such an event would be exceptional, and of very rare occurrence. In most cases we should obtain an acid or putrid liquid resulting from the production and multiplication of alien ferments.

The addition of yeast is made in consequence of the necessity of exciting through the whole bulk of wort, as soon as it is cold, a single fermentation—viz., the alcoholic, the only one that can produce beer properly so called.

The alcoholic ferments concerned in the production of beer will be found represented in several of the engravings in this work. Other ferments we may term “diseased”; these include all those that may occur spontaneously—that is, whose germs have not been directly and intentionally introduced—amongst the actual alcoholic ferments.

The expression, “diseased ferments,” is justified by the circumstance that the propagation of these ferments is always accompanied by the production of substances which are acid, putrid, viscous, bitter, or otherwise unpalatable, a consideration of commercial rather than scientific importance. From a physiological point of view, all these ferments are of equal interest and importance. The botanist, as a man of science, in contemplating nature, must give equal attention to all plants, whether useful or noxious, since they are all governed by the same natural laws, among which no order of merit could be established. The exigencies of industry and health require, however, wide distinctions.

The first engraving (Plate I.) represents the different diseased ferments, together with some cells of alcoholic yeast, to show the relative size of these organisms.

No. 1 of the engraving represents the ferments of turned beer, as it is called. These are filaments, simple or articulated into chains of different size, and having a diameter of about the thousandth part of a millimetre (about 1/25000 inch). Under a very high power they are seen to be composed of many series of shorter filaments, immovable in their articulations, which are scarcely visible.

In No. 2 are given the lactic ferments of wort and beer. These are small, fine and contracted in their middle. They are generally detached, but sometimes occur in chains of two or three. Their diameter is a little greater than that of No. 1.

In No. 3 are given the ferments of putrid wort and beer. These are mobile filaments whose movements are more or less rapid, according to the temperature. Their diameter varies, but is for the most part greater than that of the filaments of Nos. 1 and 2. They generally appear at the commencement of fermentation, when it is slow, and are almost invariably the result of very defective working.

In No. 4 are given the ferments of viscous wort, and those of ropy beer, which the French call filante. They form chaplets of nearly spherical grains. These ferments rarely occur in wort, and still less frequently in beer.

No. 5 represents the ferments of pungent, sour beer, which possesses an acetic odour. These ferments occur in the shape of chaplets, and consist of the mycoderma aceti, which bears a close resemblance to lactic ferments (No. 2), especially in the early stages of development. Their physiological functions are widely different, in spite of this similarity.

The ferments given in No. 7 characterize beer of a peculiar acidity, which reminds one more or less of unripe, acid fruit, with an odour sui generis. These ferments occur in the form of grains which resemble little spherical points, placed two together, or forming squares. They are generally found with the filaments of No. 1, and are more to be feared than the latter, which cause no very great deterioration in the quality of beer, when alone. When No. 7 is present, by itself or with No. 1, the beer acquires a sour taste and smell that render it detestable. We have met with this ferment existing in beer, unaccompanied by other ferments, and have been convinced of its fatal effects.

No. 6 represents one of the deposits belonging to wort. This must not be confounded with the deposits of diseased ferments. The latter are always visibly organized, whilst the former is shapeless, although it would not always be easy to decide between the two characters, if several samples of both descriptions were not present. This shapeless deposit interferes with wort during its cooling. It is generally absent from beer, because it remains in the backs, or on the coolers; or it may get entangled in the yeast during fermentation and disappear with it.

Among the shapeless granulations of No. 6 may be discerned little spheres of different sizes and perfect regularity. These are balls of resinous and colouring matter that are frequently found in old beer, at the bottom of bottles or casks; sometimes they occur in wort preserved after Appert’s method. They resemble organized products, but are nothing of the kind. We have remarked before, in “Studies on Wine,” that the colouring matter of wine would settle, in course of time, in that form.

It is evident that the different ferments delineated in Plate I. are worthy of thorough study, in consequence of the fermentations to which they may give rise. Care must be taken to isolate the action of each of them in fermentations which we may call pure—a condition of some difficulty, but one that may be carried out by an adoption of the methods explained in this work.

All these diseased ferments have a common origin. Their germs, infinitesimal and hardly perceptible as they are, even with the aid of the microscope, form a part of the dust conveyed through the air. This dust the air is continually taking from or depositing upon all objects in nature, so that the dust that clings to the ingredients from which our beer is manufactured, may teem with the germs of diseased ferments.

During the process of fermentation, the occult power of diseased ferments, although it may escape the observation of the brewer, is manifested in a high degree.

During the last thirty years, or so, the art of brewing has undergone a radical change, at least in Europe. This change has been effected by a partial abandonment of the process of fermentation formerly used. Thirty years ago only one kind of beer was known; there are nowadays two distinct kinds—beer fermented at a high temperature, and beer fermented at a low temperature. Each of these is subdivided into many varieties, to which different names are given, according to their strength or colour. This is the case in England, where we find porter, ale, pale ale, stout, bitter beer, and other varieties of beer, although, as a matter of fact, the English have but one kind of beer, all the English beers being fermented at a high temperature.

Let us briefly examine the differences existing between the two kinds of beer.

Formerly all beer was fermented at a high temperature. The wort, after having been cooled in the backs, was run into a large vat, at a temperature of about 20° C. (68° F.). Yeast was then added to it, and when the fermentation began to show itself, in the formation of a light, white froth, upon the surface of the liquid, the wort was run into casks, having a capacity of from 50 to 100 litres (11 to 22 gallons)—75 litres being the commonest size. These casks were placed in cellars, having a temperature of from 18° C. to 20° C. (64° F. to 68° F.). The activity of fermentation soon produced a froth that grew thicker and more and more viscous in proportion to the quantity of yeast it contained. The yeast worked out of the bung-holes and dropped into a vessel placed under the casks; there it was gathered for subsequent operations. It always exceeded the quantity used in the first instance, the ferment increasing greatly during the process of fermentation. The increase in its weight varied with the weight of yeast used and the composition of the wort. Under the ordinary conditions of brewing, where the weight of the pitching yeast was about one thousandth part of the weight of the wort, the increase is said to have been from five to seven times the weight of the yeast; but such increase must naturally have been determined by the quality of the wort, the quantity of hops used, the action of oxygen, and the proportion of barm employed. The process of fermentation lasted from three to four days. By that time the beer was finished, and had become limpid, the fermentation having been completed. The bungs could then be placed in the casks, and the beer be delivered to the customer.^[5] A certain amount of yeast still remained in the casks, and caused the beer to become thick, in transit; but a few days’ rest sufficed to restore its brilliancy, and render it fit for drinking or bottling.

Here we have an explanation of the term “high fermentation,” which has been applied to the foregoing process. This process is conducted at a high temperature, which, commencing at 19° C. or 20° C. (66° F. or 68° F.), is raised to 20° C. or 21° C. (68° or 70° F.) by the action of fermentation, which is always accompanied by an increase of heat.^[6]

This is not, however, the only reason for the use of the term “high fermentation.” We have just seen that the fermenting casks were so arranged that most of the yeast produced during the process of fermentation would rise to the upper part of the casks and work out of the bung-holes. In this practical fact we have the actual origin of the expressions “high fermentation” and “high beer,” which are used to distinguish this peculiar fermentation and the quality of beer derived from it.

As we have already observed, all beer was formerly produced by this mode of fermentation, which even at the present time is still practised in the breweries of Great Britain, where beer fermented at a low temperature is absolutely unknown.

“Low fermentation” is a slow process, effected at a low temperature, during which the yeast sinks to the bottom of the vats or casks. The wort, after cooling, is run into open wooden vats. In cooling, the wort is brought to as low a temperature as 8° C. (47° F.), or even 6° C. (43° F.), at which point it is maintained by cones or cylinders (styled nageurs, i.e., floats, by the French) floating in the fermenting vats. These floats may be filled with ice if the outside temperature requires it, as is invariably the case in summer.

The duration of this fermentation is ten, fifteen, or even twenty days. The yeast, which is produced less abundantly than in the case of beer fermented at a high temperature, is gathered after the beer has been drawn off, and is partly used in subsequent fermentations.

The term “low fermentation” is derived partly from the lowness of the temperature during the fermenting process, and partly from the fact that the yeast is gathered at the bottom, and not at the upper part of the fermenting vessels.^[7]

Beer fermented at a low temperature, of which there are several varieties, differing in colour and quality, is of Bavarian origin.^[8] The preference of the public for this kind of beer, and the increased facilities that such a beer affords the trade, are the two reasons why its manufacture has so greatly increased. In Austria, Bavaria, Prussia, and other Continental countries this new method of brewing is almost exclusively adopted.

In the Moniteur de la Brasserie of the 23rd April, 1871, may be found the following significant remarks on the increase in the production of beer fermented at a low temperature on the Continent: “The number of breweries manufacturing high beer is rapidly decreasing, whilst the number of those producing low beer is still more rapidly increasing. There were in Bohemia, in 1860, 281 breweries in which high fermentation was practised; in 1865, only 81 of these remained; in 1870, the number had declined to 18. On the other hand, the number of breweries practising low fermentation increased from 135 in 1860 to 459 in 1865, and in 1870 had risen to 831. In 1860 there were 620 breweries in which the two methods were employed; in 1865 there were 486; in 1870 only 119 remained. The number of breweries at present existing in Bohemia amounts to 968.”

In France, we are still in a period of transition; but year by year the manufacture of “low beer” is increasing, to the evident detriment of its competitor.

It is unnecessary to dwell upon certain differences existing between the two kinds of beer, such as may be traced to the preparation and composition of their respective worts. The brewing of “high beer,” by hand or machinery, is effected in one operation; the brewing of “low beer” is accomplished by successive mashings, the temperatures of which are gradually raised. These differences, and others that result from the longer boiling of the wort, in the “high fermentation” process, give rise to diversities in the composition and colour of the worts, from which circumstance “low beers” are sometimes termed white beers, in contradistinction to the others, which have a deeper colour, and are known as dark beers (bruns). The name of Strasburg is generally given to “low beer” in France, but sometimes it is called German beer.

It is easy to account for the changes introduced into the construction and working of breweries by the new process of “low fermentation.” A low temperature is essential not only to the manufacture but also to the preservation of “low beer,” and must be secured by the use of ice-cellars in which the temperature may be maintained at 5° R. or 6° R. (43° F. or 45° F.), and even at 1°, 2°, or 3° R. (35° to 39° F.) throughout the year. This necessitates an accumulation of ice and the construction of cellars of enormous extent, for the storage of the beer. “Low beer” is essentially a stock beer, especially if brewed in winter, when due advantage is taken of the low temperature of the season. It is kept in cold cellars until the spring or summer, when beer is consumed in larger quantities. It is calculated that 100 kilos. (1·96 cwt.) of ice is the average quantity used per hectolitre (22 gallons) of good beer, between the cooling of the wort and the day of sale.^[9]

In the manufacture of “high beer” we find none of these complications, nor have we in that manufacture any similar difficulty of working or expense of construction to contend against. The whole process of brewing, including the delivery of the beer, does not take more than eight days. Why should a mode of brewing so simple, so rapid, and comparatively so inexpensive, have been abandoned by the greater part of Europe in favour of a system disadvantageous to the brewer in so many respects? It would be a mistake to suppose that the sole reason for such a change might be found in the superior quality of “low beer.” That such a superiority does exist is admitted as a fact by the majority of beer drinkers; but taken by itself, this fact is not sufficient to account for the radical transformation that has taken place in the manufacture of beer, as is proved by the example of England, which, we believe, does not possess as yet one single “low beer” brewery, from which circumstance we may fairly suppose that the English have a decided preference for “high beer.”

The principal advantage of working at a low temperature lies in the fact that “low beer” is less liable to deterioration, and is less prone to contract diseases than “high beer,” especially whilst it remains in the brewery—a circumstance that places the brewer in a position vastly superior to that which he occupied in former times. With the help of ice the brewer can manufacture beer during winter and the early part of spring, for consumption in summer.^[10] “High beer,” on the other hand, must be consumed within a short time of its production. The brewer is thus compelled to manufacture it as it is wanted, and as orders are sent in, the demand for it being in a great measure dependent upon the state of the weather.

Conditions so unfavourable as these must necessarily operate prejudicially against trade. Industry requires more stability and uniformity, both in the production and the sale of its goods. “Low beer” can be brewed in large quantities at any time to be delivered at any other time, according to requirements; its manufacture, therefore, is unattended by the inconveniences which we have just noticed.^[11]

How is it that the use of ice and yeast operating at a low temperature so greatly facilitates the preservation of our beer and enables us to secure such striking advantages? The explanation is simple: the diseased ferments, which we have pointed out, rarely appear at a lower temperature than 10° C. (50° F.), and at that temperature their germs cease to be active. The adoption of low temperatures by brewers is mainly due to this physiological fact. On one occasion only have we met with active vibrios (No. 3, Plate I.), at a very low temperature; these were forming with great difficulty in wort fermenting at 5° C. (41° F.).

From this we see that the changes which the manufacture of beer has undergone during the present century have been based mainly on the diseases to which beer is liable, either during or after the process of brewing. The fact that English brewers have not as yet adopted “low fermentation” may be accounted for, in a great measure, by the difficulty of enlarging existing breweries, in cities like London, to the extent required for the new method of manufacture. Even in the event of public taste demanding a “low beer,” English brewers will hesitate a long time before converting their breweries. Such conversion would impose upon them expenses and difficulties of a very serious nature. If ever such a change should take place, it will probably be inaugurated out of London. It is, however, worthy of remark that English brewers, without adopting “low fermentation,” have introduced considerable improvements in brewing, especially in the management of the temperature during fermentation; this must be preserved within narrow and exact limits, for fear of injury to the product. It might easily be shown that these improvements have resulted from the liability of the beer to contract diseases, although this fact may not have been recognized by the brewers who have introduced them.

Besides the yeasts which belong to the two principal kinds of fermentation, there exist many varieties of alcoholic ferment that produce, each of them, a special kind of beer. Among these special beers some are deficient in taste, others in aroma, others in brilliancy. Let us suppose that in the manufacture of a beer with one of these yeasts, from which a peculiar flavour is derived, a different and inferior variety is accidentally mixed with that which we intend to use; in such a case, the inferior variety, the product of which will possess an inferior quality, will exercise such an influence on the brewing as to induce the belief that disease must be present. The microscope, if consulted, will reveal no special organism, nor any of those diseased ferments of which we have given specimens. It is in the study of yeast that we must endeavour to find the cause of the results we observe. This point, which is of the greatest importance to brewers, will become clearer as we proceed.

If we examine the practices of the beer trade, in its retail as well as in its export branches, we shall find that many of them afford evidence of the liability of the beer to deteriorate. We may cite some of these. When taken out of the ice-cellars, the beer is kept in casks of small capacity, that it may be the sooner consumed; when exposed to a high temperature, the beer will not keep sound for any length of time, but will speedily effloresce with mycoderma vini or mycoderma aceti.

Beer which is intended for bottling should not be kept for more than a month or six weeks. Even in bottling we may perceive the tendency of the liquid to deteriorate.^[12] It is necessary that the bottles, immediately after being filled, should be laid on their sides for twenty-four or forty-eight hours; they may then be placed upright; the reason for this is that the air left between the cork and the beer might give rise to the production of efflorescence. If we lay the bottles down on their sides, the oxygen of this air will be absorbed by the oxidizable substances in the liquid, and there will be little fear of germs developing themselves when the bottles are placed upright. The bottles should not, however, be left on their sides longer than forty-eight hours; otherwise the supplementary fermentation may force the corks out. Moreover, when the bottles stand upright the products of fermentation collect at the bottom, and not at the sides.

Beer which is intended for keeping, if exported or conveyed some distance off, must be surrounded with ice. Without this precaution it will ferment too much or contract some disease.

“High beer” cannot stand travelling. This kind of beer should not be exported unless the ordinary proportion of hops has been greatly increased—hop oil acting in some respects as an antiseptic, and preventing the beer from contracting diseases.^[13] The export of English beer to India and the Continent has fallen off of late years, or rather, has not increased to the extent that was anticipated; in fact, this trade has entailed great losses upon those engaged in it. It is said that an English firm lost as much as £48,000 on one consignment, which on its arrival in India was found to be all turned.

There are no breweries in hot countries, where beer would command a very large sale. It is a well-known fact that beer is a remarkably pleasant drink in tropical climates, provided its temperature be a few degrees below that of the atmosphere, but the expenses of its production would be enormous, on account of the immense quantity of ice that would be required in its manufacture and for its preservation. It is in hot countries that beer is most liable to deterioration.

Beer is said to be the beverage of northern regions, which are deprived of the vine, by the rigour of their climate. In these regions man has sought in the abundance of grain-fruit a substitute for grapes. To a certain extent this is true; nevertheless, it is an undoubted fact that beer was first brewed in Egypt, a very hot country, whence its manufacture has spread over Europe. It was called Pelusian wine, from Pelusium, a city on the banks of the Nile, which produced a beer that was held in high esteem.^[14]

Beyond a doubt, hot countries, even those in which the vine is cultivated, would consume much beer, could it but stand their high temperature.^[15] A considerable quantity of beer is now brewed in British India, but its manufacture entails an enormous outlay for ice.

The complications which result from the tendency of wort and beer to deteriorate, underlie almost all the details of the process of brewing and the sale of beer, and have been the cause of most of the changes and improvements that have been effected in brewing, during the present century.