39

Scottish Section.

LIST OF OFFICERS.

(1908.)

Chairman: Bobebt Jeffrey.

Vice-Chaii-man: W. Balunqall, M.A., F.C.S.

Committee :

John F. Bbll.

J D. Cbomdib.

Johk S. Ford, F.B.8.E., F.C.S.

T. A. GlBNDINXIKO, F.I.C.

H. A. HEDLEV.

CHABLBS HB3LOP.

Jacod Kmnqlbu.

GeOBGB LOBIUBU.

H. C. Wilsox.

Hon. Secretary: Jon?f Doull, F.C.8.,

17, Chambers Street, Edinburgh.

MEETING HELD AT THE BALMORAL HOTEL, EDINBURGH,

ON TUESDAY, OCTOBER 24th, 1905.

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 Fvffe.

The question of wort boiling, from its apparent simplicity and its

daily familiarity to brewers, is apt to bo dismissed by many as having

comparatively little influence upon the character of the beer produced.

The main effects of boiling—evaporation, destruction of diastutic

action, hop extraction, and sterilisation—arc so well known that many

brewers consider that theso exhaust the beneficial results to be

achieved by boiling their worts, and, provided they get a good

40 CANNON AND FVFFE: WOttT BOILING.

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 aro

in vogue, and although thc3C 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, bo many arc the opinions, that one usually finds a brewer to be

biassed 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 respec

tively, 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 bo thorough, it is too

often assumed thjit thia object 13 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 wo mean

pennanenco 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 cf flavour and character is frequently considered

satisfactory if the casks are sent back empty from the customer with

out complaint; but wo 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 aro 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

CANNON AND FYFFE: WORT DOILIXG. 41

the date of browing, fined and, in some cases, hopped before despatching

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 cither case it is

absolutely essential that the boors 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 invari

ably develop the well-known flavour so characteristic of frctty 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, man)* 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 tho 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 bo 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. Wo

ourselves can specify instances in which the ideal standard is closely

approached and could indicate examples of beers which are wholly

unsuited to the class of trade they attempt to satisfy. As the trade

and general public become more exacting year by year, all brewers feel

42 CANNON AND FYFFE: 1VORT BOILING.

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 duo in largo 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 tho 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 tho reasons for the lack of

stability exhibited by certain beers, we took steps to ascertain some

thing of the different conditions under which the various beers had

been brewed Among the data accumulated, we found that there

appeared to bo some connection between the manner of boiling and

tho amount of coagulable matter in the beer, that is to say, that in

the case of worts boiled in a fire copper, tho amount of deposit was

usually inappreciable, whilst with worts boiled with steam at com

paratively low pressures, a considerable precipitation was observed

when the beers were submitted to the boiling tests we have described

above. Wo then determined to conduct a series of experiments upon

wort boiling in order to ascertain how far this determined tho after

stability of tho beer. Our experiments have been of a practical

character throughout, having been conducted at a brewery. Our

observations have extended over several years; tho beers produced

have been in every caso subjected to a critical examination, and since

many of our experiments were carried out in the height of .the summer

CANNON AND FYFFB: WORT BOILING. 43

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 tho same period as on the largo scale, and, after

adjusting to the same gravity, fermented and subsequently treated in

precisely the same manner as tho bulk beer of the brewery. Henco,

we were always able to set up a kilderkin of a " fire-boiled " beer,

side by side with the usual trado 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 waB boiled at

a pressure of 4 lb., the temperature of the wort being thereby

maintained at 218° F.

During 1902—1903 wo conducted over 20 parallel experiments with

the steam-jacketed copper and the fire copper. In the steam copper

we were unable to work to tho 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, wo 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, wont

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 frettj* flavour. The

44 CAKKOX A:%TD FYKFB: WO1ST DOILIXO.

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, nicked, hopped, and stored for 7—14 days, then fined and put

on tap, brightened in 12—24 hours in winter and spring, were drink

able 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 :—

XX. Brewed June 10, 1903.

Hacked, hopped, fined, and put

up, June 20, 1903.

Si ea:n pressure, 16 1b. Fire.

June 21. Bright.

2G. Brilliant.

July 1.

3.

G.

Very slight

haze.

Hazy.

Dull.

Dull.

Brilliant.

Brilliant.

Brilliant.

Brilliant.

Bright.

Bright.

BA. Brewed Atujnd 8, 1903.

Hacked and hopped August 15,

and stored until August 22,

when fined and put up.

Steam pressure, 10 Ib. Fire.

Aug. 23. Thick. Slightly hazy.

Thick. Bright.

Thick. Brilliant.

24.

2G.

31. Slightly Brilliant,

hazy.

Sept. 2, Bright. Bright.

4. Bright. Slight haze.

These two gyles arc 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 tho 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 put, changes indicated by the eye wore accompanied by changes

CANNON AND FYFFE: WORT BOILING. 45

in the character and flavour of the beers. In every case these points

wore 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 cdnfirmed 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:—

XX.' Brewed August 12, 1904.

Racked, hopped, fined, and put up, August 23, 1904.

Steam copper with benter.

40—45 lb. pressure. Fire.

August 24 Bright. Brilliant.

29 Slightly hazy. Brilliant.

Sept 3 Dullish. Brilliant,

9 Slightly hazy. Bright.

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

46 CAXNOtf AXD FVFPE: WOUT BOILLVO.

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 some

what fuller and richer beer when new. The difference in this respect

we do not consider to be so groat 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 per

manence 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 wo 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 wo noticed a distinct im

provement 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 arc quite unable to account for this difference, although, on looking

through tho results of the previous year's brewing, it is to be noted

that the beers usually behaved better 1)}' the former than by the latter

procedure:—

CANNON AKD FVFFE: WOltT BOILING. 47

XX. Brewed August 19, 1905.

Hacked, hopped, and fined,

August 19.

Steam pressure, GO 1b. Fire.

Aug. 30. Bright. Bright.

Sept. 3. Bright. Brilliant.

7. Bright. Brilliant

12. Bright. Bright.

14. Slightly hazy. Bright.

BA. Breweil August 26, 1905.

Racked, hopped, and fined,

September 4.

Steam pressure, 4 1b. Fire.

Sept. 5. Bright. Bright.

7. Bright. Brilliant

14. Bright Brilliant

20. Slight haze. Bright

Tlic beere 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 largo 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 tho 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 tho high temperatures which have been recorded in

individual cases whoro high gravitios and huge deep coppers have

been emplojTed. 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 tho same, viz., 212°—213° F.

But as we have shown that, even with tho small fire copper notwith

standing the low wort temperature, a very efficient cooking of the

wort was secured, as evidenced by tho greater stability of tho beers,

it is apparent that wo must look to some other factor than mere

temperature of the wort, to account for the marked differences

48 CASXON AND FYFFE: AVORT IIOILING.

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 arc therefore forced to the conclusion that actual wort tem

perature is of little moment so far as the stability of the beer is

concerned, and we arc 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 systerns 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 tem

peratures 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

CAXXON AND FYFFE: WOHT BOILING. 49

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 bo 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; tho "setting" of the copper, the size of tho furnace, and

the arrangement of tho flues, the outcome of sound practical know

ledge. Hence the brewer was fairly safe in relying upon the craft of

the coppersmith and tho skill of the adept bricklayer who made u

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

tho 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

tho copper, tho engineer has devised all sorts of means for applying

heat in various places; at the bottom, at the side and in the middle.

By tho 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 lets

tumultuous boil is secured. But whilst it is a source of satisfaction to

VOL. III.—1. E

50 CANNON AND FYFFE: WORT BOILING.

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 bo 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 8team 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.

Wo 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. Wo believe, however, that

the true explanation of wort cooking will bo 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 duo 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 some

thing 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 phosphotungstic 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 condi

tions in the brewery. In order to facilitate comparison, all results

have been calculated to 1055 gravity :—

Pi

to

(a)

Cupric

hydrate

precipitate,

Nx6'25=Albumins

(b)

Phosphotungstic

precipitate,

Nx625.

b-a=

Peptone

Totalb=Amide

Total

Steam,

161b.

0-086

0-228

0172

0*486

Fire.

0*080

0-118

0*263

0-461

Steam.

251b.

0-076

0-160

0-192

0-428

251b.

0-085

0-138

0'224

0-447

Fire.

0-067

0108

0-247

0422

Steam,

851b.

0-110

0*044

0-275

0-429

Fire.

0*087

0-061

0-269

0-418

Steam,

35

1b.

0*085

0045

0-238

0*368

Fire.

0-075

0-045

0-233

0*354

(a)

Cupric

hydrutc

precipitate,

3x625«

Albumins

(b)PhosphotungBtic

precipitate,

Nx6'25.

b-a=Peptono

Total

b~Amide

Total

Steam.

401b.

O'lOl

0048

0-268

0-413

401b.

0102

0-033

0*247

0382

Fire.

0078

0-068

0-251

0-397

Steam.

0-055

0*031

0-267

0-853

Fire.

0055

0-024

0-313

0-392

Pressure.

3*

0-080

0*141

0-206

0-427

3|

0057

0-128

.0-245

0-430

Fire.

0-056

0-120

0251

.

0-427

3- a 3 g

52 CANNON AND FYFFE: WOUT BOILING.

In considering the above figures, which represent the residual

nitrogen in tho 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 evidenco 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 tho case with low-pressure boiling that the

albumin and poptone nitrogen is appreciably higher.

It is well known that the albuminoids of malt embrace numerous

constituents, including soluble albumins, albumoses, peptones, amido

acids, and amino bases. These have been derived from the insoluble

proteid of tho barley, partly by the changes during malting and

partly by tho 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 amido acids and

amine bases which are more readily assimilated by tho yeast plant.

In the same way the changes in tho character of tho nitrogenous

constituents, begun on tho malting floor and in tho mash-tun, are

undoubtedly cotitinued in the copper, with, however, this difference^

that in the coppor this degradation is favoure4 by high temperatures

and the acidity of the wort. It has boon 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 con

sidering the question of efficiency of boiling.

Windisch says : " About two-think of the albuminous substances of worts

are precipitated on boiling. This occurs in a very short time, pro

longed boiling causing a portion of tho albuminous substances to

redissolve, which leads to albumin and gluten turbidity" The italics

are ours.

Matthews (J. Fed. Tnst. Brewing, 1897, p. 388), in discussing the

nutrition of yeast, says: " The free acids of the hop and the acid phos

phates of the worts have a strong modifying effect on tho 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

CANNON AND FYFFE: WOUT BOILING. 53

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 tho action of bacteria during the period of tho

activity of the yeast."

In the above quotations tho question of temperature is not referred

to, and in no published work upon tho subject of boiling has the

question of temperaturo and its bearing upon stability been referred

to. As we consider temperaturo, or more accurately the surface

temperature to which the wort constituents are exposed, to bo the

real determining factor, we feel that we may, without unduly

extending our paper, record a few analyses showing tho differences

in the nitrogenous matter of worts when boiled under different

conditions.

Coaguiablo

AJbumius

Peptone

Amide

Totnl

Mash-tun

wort.

0*063

0*249

0*245

0*187

0*74*

Steam boiled,

161b.

0 026

0-165

0*189

0*256

0*626

Fire.

0-009

0*146

0-192

0-254

0-601

Steam,

0-081

0-105

0-109

6-368

0*663

Fire.

0-035

0-092

0*123

0'365

0*615

In another experiment we attempted to follow tho mash-tun worts

throughout tho boiling operation, but there are great difficulties in

securing samples which will enable close comparison to bo made. In

tho following table the results calculated to 1055 gravity are given for

each copper:—

Albumins

Peptones

Amides

Total

1st wort

before boiling.

0*200

0*185

0-467

0*852

1st wort

after boiling

by steam.

0-156

0-170

0*431

0 807

2nd wort

beforo boiling,

0*247

0 *197

0*464

0-908

2nd wort

after boiling

by etcum.

0-J71

0*149

0*412

0*732

54 GANNON AKD FYFFE: WORT BO1LJNG.

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

under:—

Albumins

£optoncsAmides

Total

Wort.

0-1370'133

0*440

0-710

Steam.

Beer.

0 -0760 160

0*192

0*428

Wort.

0-126

0-130

0-446

0-700

Fire.

. Beer.

0-067

0*103

0-247

0-422

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 tho whole of the differences exhibited

when worts are boiled by steam and by fire respectively, nor do wo

wish to bo 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 tho sole determining

cause of disease in beer is erroneous and unjustified in tho light of

man}* 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 tho growth

DISCUSSION. 55

of disease organisms rather than the continued isolation of innumer

able 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 tho same infection remained perfectly stable,,

owing to certain subtle changes which had taken place during the

boiling of the wort by fire.

Discussion.

The Chairman, in opening tho 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 bo wrongly attributed to a "good

rousing boil" and be productive of evaporation rather than true

boiling and cooking of worts. Ho (tho 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 bo loss satisfactory than when boiled with fire or

with steam of sufficiently high pressure.

Mr. Fokd 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 replj' 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,

5G DISCUSSION.

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 tho

control of all the practical work. In most cases the yeast was taken

off a previous brow 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 tho work. Tho haze in

the majority of c«isc3 was, without doubt, duo 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 appear

ance which was not appreciated. His point entirely was that if the

cooking of the wort and the precipitation of the albuminoids was

•complete tho beers were proof against thoanfection. 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 experi

ments, he pointed out, were mostly carried out in tho summer time,

and the haze was not due cither to gluten or resin, but almost entirely

JLo 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 bo 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 apprecia

tion of Me3srs. Cannon and Fyffe's valuable paper on wort boiling, I

DISCUSSION. 57

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 whicli wo got at 16 lb., the worfc 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 tho 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 lire 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 wo

vrill hear more from them on this interesting and important subject."