Wort Boiling – Steam vs. Fire


Mr. T. A. Glendinning, F.I.C., in the Chair.

The following paper was read and discussed.

Wort Boiling
by Matthew J. Cannon and William Fyffe.

The question of wort boiling, from its apparent simplicity and its daily familiarity to brewers, is apt to be dismissed by many as having comparatively little influence upon the character of the beer produced. The main effects of boiling—evaporation, destruction of diastatic action, hop extraction, and sterilisation—are so well known that many brewers consider that these exhaust the beneficial results to be achieved by boiling their worts, and, provided they get a good vigorous boil, and boil for a definite time, it is too often presumed that the full benefits which the copper can bestow have been exhausted. Throughout the breweries of the United Kingdom many methods are in vogue, and although these may be reduced to two systems—heating by fire and boiling by steam—the variety to be met with in practice is proof that no very definite opinion exists as to the best means by which the boiling of wort should be accomplished. As a matter of fact, be many are the opinions, that one usually finds a brewer to be biased in favour of the particular system he employs. It is interesting too, although frequently confusing, to refer to the many authorities who have expressed their opinions respecting the process of boiling the wort in the copper. The diversity of opinion is so unanimous that it would be a comparatively easy task to present a very strong case in favour of any system. The influence of fire and steam boiling respectively, upon colour, flavour, etc., has been frequently discussed and different views expressed as to the manner in which they are affected by the different systems, but although there is a general consensus of opinion that the “cooking” of the wort should be thorough, it is too often assumed that this object is achieved in any copper, provided there is good circulation and vigorous ebullition. We have even heard eminent authorities maintain that there is no difference in the cooking of wort, whether boiled in a steam-jacketed pan working at a low steam pressure or in a fire-heated copper.

In the present paper we regret that we are unable to deal with the many aspects of lire and steam boiling; we wish to deal more particularly with the influence exerted during boiling upon the stability of the finished beer. By stability of a beer we mean permanence of brightness, flavour and character over lengthened periods. We know that the term blight is frequently employed to designate a beer which appear clear if not too closely scrutinised, and permanence of flavour and character is frequently considered satisfactory if the casks are sent back empty from the customer without complaint; but we have had in mind a beer of a more ideal type, one which will satisfy the ideal of the brewer who subjects his beers to continual and rigorous critical examination in the brewery cellar.

In general, there are two methods of dealing with beer before sending it from the brewery to the customer. In the one, the beer is racked from unions or settling squares at from 7—10 days from the date of brewing, fined and, in some cases, hopped before dispatching to the customer. In the other, the beer is racked, say, seven days from the date of brewing, hopped and stored for a week or a fortnight for conditioning, fined, and then sent out. Now, in either case it is absolutely essential that the beers should drop bright quickly in from 12 to 48 hours and that the latter period should not be exceeded. The beers should remain brilliant or bright, and be perfectly stable during a period of 14 days or a month, summer or winter. Usually when beers are racked, fined, and sent out 7—10 days from date of brewing, they drop bright quickly at any period of the year, but it is our experience that, during the hot months of the year, many such beers go back in 7 or 10 days; that is, they become hazy and invariably develop the well-known flavour so characteristic of fretty beers. Sometimes these beers recover their original brightness, but even in these cases a thinness is noticeable, and, upon the palate, a harsh, bitter flavour distinctly apparent.

In the other case, beers racked, hopped, and stored for 7—14 days before being fined and sent out for consumption, invariably brighten quickly enough during the winter and spring season; but, during summer and autumn, many beers thus treated frequently take several days to brighten, and sometimes never become perfectly brilliant.

Now, it is the ideal of the brewer to avoid these troubles. Working by either method he aims at the production of a beer which will drop bright quickly in the customer’s cellar at all seasons of the year, which will not show signs of sluggishness during the hot months of the year, and which will exhibit permanence of brightness and flavour for three weeks or a month at least at any  season. The brewer who secures these results will satisfy his customers and be spared the endless worry and loss entailed by complaints and returned beer. That some breweries achieve and others very nearly attain to these desirable results is well known to most brewers, and, we fear, we must also admit that the beers of some breweries fall far short of these requirements and cannot be relied upon for any length of time. We ourselves can specify instances in which the ideal standard is closely approached and could indicate examples of beers which are wholly un-suited to the class of trade they attempt to satisfy. As the trade and general public become more exacting year by year, all brewers feel the necessity of obtaining quick brightening and stability in their beers, for these are days of severe competition, and the consumer is a discriminating individual, quick to note any point of superiority exhibited by one beer over another. In a word, trade follows quality.

For some years we have had this subject under review, and the results of experimental investigation and close observation during the past four years have led us to believe that the differences in the time of brightening and the stability of beers of different breweries, so marked in summer and autumn, are due in large measure to the different methods of boiling the wort, assuming always that equal conditions prevail as regards cleanliness of plant and proper manipulation of materials. It was the observation of one of us, that when beers were boiled in a flask and allowed to stand after being made up to their original volume, that considerable differences were exhibited in the amount of deposit thrown out on cooling. It was further observed that tin’s test was a good index to the stability of a beer. Those beers throwing a heavy flocculent deposit, invariably showed haziness and an alteration in flavour at an early date, whilst those in which a very slight precipitate was observed were freer from these defects over much longer periods. An examination of these deposits showed them to consist mainly of albuminous matter. As we were chiefly concerned in discovering the reasons for the lack of stability exhibited by certain beers, we took steps to ascertain something of the different conditions under which the various beers had been brewed. Among the data accumulated, we found that there appeared to be some connection between the manner of boiling and the amount of coagulable matter in the beer, that is to say, that in the case of worts boiled in a fire copper, the amount of deposit was usually inappreciable, whilst with worts boiled with steam at comparatively low pressures, a considerable precipitation was observed when the beers were submitted to the boiling tests we have described above. We then determined to conduct a series of experiments upon wort boiling in order to ascertain how far this determined the after stability of the beer. Our experiments have been of a practical character throughout, having been conducted at a brewery. Our observations have extended over several years; the beers produced have been in every case subjected to a critical examination, and since many of our experiments were carried out in the height of .the summer season of the years 1902—1905, we think that our observations will be interesting and of value to brewers.

Our first experiments wore carried out on parallel lines with a steam-jacketed open copper, working at a steam pressure of 16 lb., and a fire copper heated by gas. We were able to boil about two-thirds of a barrel in the fire copper. Usually a portion of the wort was withdrawn from the large copper after making up. This portion was well boiled for the same period as on the large scale, and, after adjusting to the same gravity, fermented and subsequently treated in precisely the same manner as the bulk beer of the brewery. Hence, we were always able to set up a kilderkin of a “fire-boiled” beer, side by side with the usual trade beers in store. These experiments were conducted during the years 1902—1903. During 1904 we were able to continue our experiments with an open steam copper, fitted in addition with a tubular heater. During this period we were able to work at steam pressures up to 45 lb., and we made numerous parallel brews working with 25, 35, and 45 lb., and our open fire copper. During 1905 we have pursued the subject, working with a pressure-boiling domed copper. In this the wort was boiled at a pressure of 4 lb., the temperature of the wort being thereby maintained at 218° F.

During 1902—1903 we conducted over 20 parallel experiments with the steam-jacketed copper and the fire copper. In the steam copper we were unable to work to the full boiler pressure of 45—50 lb., owing to the marked tendency to fob which this copper exhibited. It was not practicable, in fact, to work beyond a steam pressure of 16 lb. Although this copper had been used many years, no one had ever suggested that its working was at fault. Circulation and evaporation were good; even under the stated conditions the beers produced were good and stood well in the public favour, although not attaining to the high ideal standard we have indicated Looking over our notes of this period, we find that the steam-boiled beers, when racked, hopped, fined, and put up on tap 7—10 days from date of brewing, brightened in 12—24 hours in winter and spring, went back slightly in 8—10 days, but not enough to give trouble or cause complaint. In summer and autumn, however, these beers, although brightening in 12—24 hours, generally went back very much in 8—10 days, developing a characteristic fretty flavour. The same beers racked, hopped, and stored for 7—14 days, then fined and put up—brightened 24—48 hours in the winter time and remained stable two or three weeks. In summer and autumn, these beers generally took four, five, and sometimes six days to reach perfect brightness, and in sonic cases never attained to it.

The beers produced by fire boiling, racked, hopped, fined, and put on tap 7—10 days after brewing, quickly dropped bright in summer and winter, and remained perfectly stable for over 14 days during the hottest periods of summer and for over a month in winter. The same beers, racked, hopped, and stored for 7—14 days, then fined and put on tap, brightened in 12—24 hours in winter and spring, were drinkable in 24 hours in summer and autumn, and usually bright, and in some cases brilliant, in 48 hours. Details of the behaviour of the beers in tabular form will enable you to appreciate the differences :—

These two gyles are typical of the many experiments we conducted during this period. The difference between the two beers is so marked that no one will, we think, dispute our conviction that the boiling is the determining factor contributing to these results. When we remind you also that these results have been obtained upon the same gyle, and that in many cases we fermented quantities of steam-boiled wort in the same amount and under the same conditions as the fire-boiled wort, you will understand that we have not neglected to eliminate extraneous conditions which might vitiate our deductions. Moreover, we wish to point out, changes indicated by the eye were accompanied by changes in the character and flavour of the beers. In every case these points were distinctly in favour of the fire-boiled beers.

We suppose that it will be suggested that such low steam pressures are fatal to stability, but we would point out that it is within our experience and knowledge that low pressures during boiling are by no means uncommon, and we have experienced a certain amount of scepticism as to the need of higher pressures, provided a good boil is secured. It is, therefore, with considerable satisfaction that we have been able to continue our work with higher steam pressures. In these cases the open copper was fitted with a vertical multitubular heater, and we were able to work up to 45 lb., the limit of the boiler pressure available. We secured violent ebullition, a thorough splash-boil keeping down fob, being maintained during the whole period of boiling, the evaporation being nearly double that of the former system. We conducted similar parallel experiments) but although we noticed an improvement in the case of the steam-boiled beers, the improvement was not so great as one would have expected. On the whole, we may say that the beers were more stable, an opinion which was confirmed by the majority of those who were called upon to pass judgment upon the respective beers. They were, however, far from attaining to the results shown by the fire-boiled beers, our experiments with these giving practically the same results as in the two former years. An example taken from our notes will illustrate the differences:—

On examining these beers by the boiling test we noticed a marked difference in the deposits. The steam-boiled beer gave a heavy deposit, whilst the fire-boiled beer showed merely an inappreciable quantity of a light amorphous nature. In many cases during this season the steam-boiled worts showed deposits of a stringy nature similar in appearance to shredded horse-radish. It may be asked how far the character of the beers from the fire-boiled worts had been altered. We give it as our opinion that, on the whole, the fire-boiled worts gave a beer of a drier character; the steam-boiled worts, a somewhat fuller and richer beer when new. The difference in this respect we do not consider to be so great when we take into account the after deportment of the respective beers. We have no hesitation in saying that the flavour of our fire-boiled beers was of a character which would secure higher appreciation from the customer. It was distinctly noticeable that, although materials were in every case the same, the steam-boiled beers evinced a harsh hop bitterness which remained upon the palate, whilst the fire-boiled beers wore of a much cleaner and more delicate character; the fire boiling having apparently been more effective in cooking the wort and in giving what we may well express as the more thorough blending of the constituents of the wort; and these conclusions were also confirmed by the opinions of those who had an opportunity of tasting the different beers. Further, the permanence of the “fire” beers and their freedom from the flavours produced by changes similar to those which the steam-boiled beers undergo, have left upon our minds a firm conviction as to the relative qualities of the respective beers.

During the spring and summer of this year we have been able to supplement our work by the results obtained by the use of a domed pressure copper working at 4 lb., a wort temperature of 218° being regularly maintained. With this system we noticed a distinct improvement in the case of the beers racked, hopped, fined, and put on tap 7—10 days from the date of brewing. During the summer these beers still went back in 7—10 days, but generally were less hazy than the beers produced by the two former systems. They recovered their brightness more quickly and did not develop such a harsh, bitter flavour after the haziness had passed off. Strange to say, however, we did not notice such an improvement in the case of beers racked, hopped, and stored for seven days before fining and putting on tap. We are quite unable to account for this difference, although, on looking through the results of the previous year’s brewing, it is to be noted that the beers usually behaved better by the former than by the latter procedure:—

The beers subjected to the boiling test still showed a flocculent deposit, but this was much smaller in amount than in the previous systems, although still greater than the deposit from the fire beers.

The typical examples which we have recorded, which have been selected from the large number of brewings we have had under our observation during the past four years, incontestable show how the stability of beer is influenced by the nature of the boiling.

In dealing with the question of wort boiling, most authorities have insisted that the temperature of the wort exercises by far the most potent influence upon the “cooking.” Instances have been recorded where the wort in deep fire-heated coppers has reached a temperature of 216°—217° F., but we have been able to demonstrate that with very deep coppers fitted with tubular “heaters,” and having excellent circulation, that, although the wort is raised several degrees above 212° F., the beers still show a certain lack of stability, and throw appreciable deposits when boiled. But it must be remembered that in the majority of cases the coppers are of such a size, and the gravity of the worts sufficiently low as to make it practically impossible to raise the wort to the high temperatures which have been recorded in individual cases where high gravities and huge deep coppers have been employed. In our own series of experiments we found in the large steam-heated copper, and the small fire-heated copper, the temperature of the wort was practically the same, viz., 212°—213° F. But as we have shown that, even with the small fire copper not with-standing the low wort temperature, a very efficient cooking of the wort was secured, as evidenced by the greater stability of the beers, it is apparent that we must look to some other factor than mere temperature of the wort, to account for the marked differences between boiling with fire and boiling by steam. If the temperature of the wort alone determined the “cooking” of the wort and the after stability of the beer, one would expect that in a properly constructed steam copper, working at a pressure of, say, 16 1b., satisfactory, results should be obtained, since the temperature of steam at 16 lb. pressure is 240° FM or 20°—25° above the temperature to which the wort can possibly be raised in practice.

We are therefore forced to the conclusion that actual wort temperature is of little moment so far as the stability of the beer is concerned, and we are of opinion that it is rather the manner in which the heat is conveyed to the wort, which determines the “cooking” of the wort, and fixes the stability of the beer. Let us consider for a moment the conditions under which heat is transferred to the wort in the systems of fire and steam boiling. With a fire heated copper we have upon one side of the copper plates an intense heat, on the other, comparatively cool wort. If the setting of the copper is well designed, circulation of the wort is excellent, and a vigorous boil results; but the wort momentarily impinging upon a super-heated surface is subjected to a high temperature and this we believe is the secret of the observed differences between fire and steam heating. In the latter case, even working with 60—80 1b. steam pressure, the contact temperature never exceeds 279*—300° F.f whilst with the firc-hcated copper the temperature of the plates far exceeds these temperatures.

Schwachofer has shown that the temperature of the furnace gases may be as high as 1100°—1500° F., and measurements of the actual temperatures of the plates on the fire side showed that a limit of 400° F. was reached at the hottest part of the furnace, and temperatures of 270°—280° F. wore indicated at cooler points along the flues. That contact temperature has an important bearing upon the stability of the beers was confirmed in an unexpected manner during the course of our experiments. The beers, boiled in our fire copper, suddenly, and without apparent reason, showed a lack of stability, they quickly showed haziness, and their character was not so permanent; they were, in fact, little better than the beers produced by boiling with steam. On investigation, it was found that the gas burner employed for heating the copper had become dirty, so that instead of burning with the usual non-luminous Bunsen flame, a luminous smoky flame resulted. In consequence, the bottom of the copper had become covered with soot. Since soot or carbon is a bad conductor of heat, it was evident that the contact temperature had been lowered to a point approximating to the temperatures of the surfaces of a steam-heated copper. We thoroughly cleaned the burner, and removed the coating of soot, and with our first trial we again obtained results which showed the superiority of the fire-boiled over the steam-boiled worts.

In drawing attention to the unmistakable differences in favour of fire boiling, we wish it to be distinctly understood that we have no desire to unduly laud the one or condemn the other; but we do wish to direct attention to the conditions under which these two systems are applied practically in our breweries. The old-fashioned fire copper, whether small or large, was usually an efficient portion of the plant. Its form and dimensions were based upon ascertained data and experience; the “setting” of the copper, the size of the furnace, and the arrangement of the flues, the outcome of sound practical knowledge. Hence the brewer was fairly safe in relying upon the craft of the coppersmith and the skill of the adept bricklayer who made a speciality of copper setting. With the introduction of steam, however, it is to be feared that the same technical knowledge and skill, upon the part of the engineer and architect, has not been brought to bear upon the question of wort boiling. The prime factor in the employment of steam is economy, and economy has, unfortunately, been allowed to outweigh every other consideration. Instead of the well-proportioned old-fashioned fire copper, we have a heterogeneous collection of vessels of all shapes and sizes—flat-bottom rounds, flat-bottom boiling squares and steam jacketed pans of small diameter fitted with wide shelving lengthening pieces to increase capacity—all of which have serious defects, and have been constructed in utter defiance of the principles of circulation. Instead of effective heat being applied at the bottom of the copper, the engineer has devised all sorts of means for applying heat in various places; at the bottom, at the side and in the middle.

By the aid of pans, which frequently cannot be kept free from condensed liquor, of steam coils of curious shape and fantastic arrangement, of heaters of various design, and by the use of steam traps which are frequently too small or faulty, a more or less tumultuous boil is secured. But whilst it is a source of satisfaction to the brewer that the evaporation is rapid, and the engineer takes credit that the boiling is accomplished with a minimum consumption of coal, it is to be feared that in too many cases the stability of the beer is defective since the cooking of the wort, upon which so much depends, has not been achieved. When we add further that in the majority of cases an effective and uniform pressure is seldom maintained owing to the limitations of the plant employed, too small boiler capacity for the work of the brewery, and sometimes the negligence of the stoker, we think we have pointed out sufficient of the disadvantages of steam boiling to convince most brewers that the conditions under which steam boiling is usually effected leaves much to be desired, and that such conditions severely handicap them in their efforts to brew beers possessing the requisite stability.

We have alluded to the effective boiling of the wort as “cooking”; a colloquial term which will be readily understood, although its significance is not so readily appreciated. We believe, however, that the true explanation of wort cooking will be found in the investigation of the changes or modification which the albuminoids of the malt wort undergo when subjected to efficient heating. It is usually assumed that the most important change in the albuminoids is the conversion of a portion of them into an insoluble form, partly due to coagulation by heat, and partly by the influence of hop tannin. The precipitation by hop tannin is, however, problematical, and the coagulation of the malt albumins is not complete at 212° F., so that it is apparent that something beyond removal of a portion of the albuminoids is necessary to determine the stability of a beer. On examining a number of beers we have been struck by the differences which they have exhibited when a rough separation of the albuminoids is attempted. We put forward our figures with reserve, as we know that the exact determination of any one nitrogenous constituent of malt wort is at present an impossibility. By the use, however, of Stutzer’s reagent (cupric hydroxide), phospho-molybdic, or phosphotungatic acid, an approximate estimate of the bodies belonging to the albumin, peptone, and amide class can be arrived at. In the following table we give details of the results obtained in this manner with beers boiled under different conditions in the brewery. In order to facilitate comparison, all results have been calculated to 1055 gravity :—

In considering the above figures, which represent the residual nitrogen in the beers, it is noticeable that appreciable differences exist in the amount of the different types of albuminoids. In the fire-boiled beers there is distinct evidence that the residual nitrogen exists to a greater extent in the more stable form of amide nitrogen, and that the less stable forms belonging to the albumin and peptone class are present in less amount than in the steam-boiled beers, and it is particularly the case with low-pressure boiling that the albumin and peptone nitrogen is appreciably higher.

It is well known that the albuminoids of malt embrace numerous constituents, including soluble albumins, albumoses, peptones, amide acids, and amino bases. These have been derived from the insoluble proteid of the barley, partly by the changes during malting and partly by the further modification in the mash-tun by the agency of the enzyme peptase. This degradation of the complex albumin molecule into simpler substances of a more stable character has an important bearing upon the question of yeast nourishment, since it is the simpler nitrogenous bodies belonging to the amide acids and amine bases which are more readily assimilated by the yeast plant. In the same way the changes in the character of the nitrogenous constituents, begun on the malting floor and in the mash-tun, are undoubtedly continued in the copper, with, however, this difference, that in the copper this degradation is favoure4 by high temperatures and the acidity of the wort. It has been before suggested that the possibility of modification of the albuminoids in the copper, other than precipitation, is a point which should not be lost sight of in considering the question of efficiency of boiling.

Windisch says : “About two-thirds of the albuminous substances of worts are precipitated on boiling. This occurs in a very short time, prolonged boiling causing a portion of the albuminous substances to re-dissolve, which leads to albumia and gluten turbidity” The italics are ours.

Matthews (J. Fed. Inst. Brewing, 1897, p. 388), in discussing the nutrition of yeast, says: “The free acids of the hop and the acid phosphates of the worts have a strong modifying effect on the albuminoids of the wort. The net results seem to be a not insensible reduction of the total nitrogen, and a slight diminution of the peptones and a marked increase in the amides, and the changes are in all probability favourable to the nutrition of tho yeast besides conferring on the wort a certain stability of composition and protecting it in an extra-ordinary way against the action of bacteria during the period of the activity of the yeast.”

In the above quotations the question of temperature is not referred to, and in no published work upon the subject of boiling has the question of temperature and its bearing upon stability been referred to. As we consider temperature, or more accurately the surface temperature to which the wort constituents are exposed, to be the real determining factor, we feel that we may, without unduly extending our paper, record a few analyses showing the differences in the nitrogenous matter of worts when boiled under different conditions.

In another experiment we attempted to follow the mash-tun worts throughout the boiling operation, but there are great difficulties in securing samples which will enable close comparison to be made. In the following table the results calculated to 1055 gravity are given for each copper:—

The mixed worts before, and the beers after, fermentation gave as under:—

In presenting these results, which we are bound to admit are incomplete in many respects, we have no desire to put forward any definite theory to account for the whole of the differences exhibited when worts are boiled by steam and by fire respectively, nor do we wish to be dogmatic in our suggestions as to the changes occurring in the constitution of the albuminoids of the wort during boiling. Much further work is obviously desirable, for the experiments we have outlined open out a field of investigation, which, if continued, cannot fail to disclose profitable and more definite knowledge of some of the changes occurring during the brewing process. During the last two decades, biological science has progressed with enormous strides, and its results have had an important bearing upon practical brewing. We venture to think, however, that this tendency to consider the mere presence of an organism as the sole determining cause of disease in beer is erroneous and unjustified in the light of many facts of common practical knowledge. The attitude engendered by this belief has led to the neglect of the purely chemical side of the subject, and the important relation which the constituents of the soil bears to the development of an organism has been overlooked. Biological science abounds in examples, indicating that organisms either do not develop in media which are devoid of constituents necessary to their nutrition and well-being, or that their growth is fostered by the presence of small quantities of some constituent which they are able to readily assimilate. It is not, therefore, going beyond present-day facts if we suggest that the work of the future lies in the direction of discovering the nature of the food necessary to the growth of disease organisms rather than the continued isolation of innumerable species of ubiquitous organisms. In a word, we believe the stability of a beer largely depends upon the formation in the wort of constituents which are readily assimilated by yeast. By their elimination during a vigorous fermentation by a healthy yeast, the food necessary to the growth of disease organisms disappears. Our experiments at least show that in specific cases, beers which were exposed to precisely the same infection remained perfectly stable, owing to certain subtle changes which had taken place during the boiling of the wort by fire.

The Chairman, in opening the discussion, remarked that his; experience of steam boiling had been that a perfectly stable and good beer could be got provided one boiled properly. If, as he understood, Mr. Cannon’s experiments were conducted with low pressure steam at 16 lb., it was not surprising that disappointing results were obtained, and therefore he. asked Mr. Cannon if he had tried steam boiling with an efficient coil or jacket, because fountains and circulators caused a great deal of movement which might be wrongly attributed to a “good rousing boil” and be productive of evaporation rather than true boiling and cooking of worts. He (the Chairman) had worked with fire coppers and steam coppers at a pressure of 35—40 lb. side by side, but had not found differences in brightness and stability of the resulting beers. When boiled with low  pressure steam beers were undoubtedly apt to be less satisfactory than when boiled with fire or with steam of sufficiently high pressure.

Mr. Ford asked what the nature of the haze was which Mr. Cannon took as a criterion of instability. Was it due to albuminous matter, wild yeast or bacteria?

Mr. Ballingal asked if the yeast crops from the first pitchings had been tried in other brews, in other words did Mr. Cannon carry forward his yeast from one experiment to another?

Mr. Cannon in reply said there was no doubt that they had a thorough boiling in their copper working, it being a well constructed steam jacketed copper. He was not prepared to say that a fire copper was to be their salvation and a steam copper their damnation, as he believed that one could have a fire copper boiling badly and the beer would be no better than with a steam copper, but in the majority of instances he maintained the steam was applied in such a way that beers of very doubtful stability were obtained. As regards the crops of yeast, he was afraid he could not answer off-hand, as his colleague, Mr. Fyffe—who had been unable to come north with him—had the control of all the practical work. In most cases the yeast was taken off a previous brew on a large scale and used for pitching both fermentations. He fancied there were some experiments made in which they were pitched from one brew to another. In their experiments it was not considered an important point, and he did not think it had much influence on the nature of the work. The haze in the majority of cases was, without doubt, due to the presence of a secondary yeast, as the beers were not subject to gluten haze or resin haze. In this particular brewery there was a pet secondary yeast -which used to make its appearance and give this greyish appearance which was not appreciated. His point entirely was that if the cooking of the wort and the precipitation of the albuminoids was complete the beers were proof against the infection. Other forms of haze did show at times, but it was found in the winter time that fire-boiled beers were not subject to chilling but would remain brilliant, while steam-boiled beers not infrequently showed haze. The experiments, he pointed out, were mostly carried out in the summer time, and the haze was not due either to gluten or resin, but almost entirely to secondary yeasts.

Mr. Ford, in thanking Mr. Cannon for his explanation, said that probably this contamination by wild yeast might account for the difference of result noticed by the Chairman and Mr. Cannon. He was in agreement that certain chemical changes would be brought about by direct fire boiling which would not be by steam boiling. Possibly in the fire-boiled wort there might be a greater degree of acidity, which as yet there was no way of measuring. It was fairly certain that the initial state of the wort as regards this had a distinct influence on the purity of the fermentation, and on the resulting beer.

A hearty vote of thanks to Mr. Cannon for his paper and to the Chairman for presiding terminated the meeting.

Mr. John F. Bell wrote as follows:—”In expressing my appreciation of Messrs. Cannon and Fyffe’s valuable paper on wort boiling, I beg to state in support of same that my experience of steam boiling, as regards the keeping qualities of a beer, is similar to that of the authors’, and although they seem to have boiled their worts at a low pressure, it is questionable if a higher pressure would have produced better results. I have boiled wort from 16 lb. up to 40 lb. pressure in deep steam jacketed open coppers with the same unsatisfactory results at 40 lb., to those which we got at 16 lb., the wort being actually at a higher temperature than that given by a fire copper, which leads one to assume that the difference in thorough cooking must be caused by the very much higher heat which the bottom layer of wort conies into contact with when boiled by fire. In my opinion, however, the question will never be satisfactorily solved until the actual nature of the changes which take place during boiling is found out. That a wort of greater stability is obtained by a fire boil seems to be the general rule, and it is probable that brewers who have been successful with steam boiling, owe their success, not to the thorough cooking of their wort, but to the use of good sound materials, which in all probability would stand even worse treatment than that which is given it by insufficient cooking. The authors are to be congratulated on their experiments so far as they have gone, and it is to be hoped that we will hear more from them on this interesting and important subject.”

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