12 [J. Inst. Brew.

HORACE BROWN MEMORIAL LECTUREA CONSPECTUS OF BREWING PROGRESS

By L. R. Bishop

Horace Brown, who started as a brewer just over a hundred years ago, was anoutstanding pioneer in the introduction of science to explain and guide brewing

practice. His own and Pasteur's work saved brewing from repeated crises due tospoilage infections and so made it safe to brew thoughout the year. Attempts to

control infection gave rise to Brown's great interest in the nitrogen compounds andled him to notable discoveries, apart from his outstanding work in many other fields.

The writer followed with researches on the nitrogen compounds of barley, malt,wort and beer. These are summarized here and the potentialities for further developments today in the stuJy of proteins are outlined. Against the background of

the changing scene in brewing, a summary is given of the writer's further work onthe agricultural aspects of barley growing, on barley germination and malting andon "sediment action" and yeast nutrition in fermentation. In addition a summary isgiven of his contributions in biological engineering, to continuous fermentation andto a scientifically-based conditioning process, using lupulin extracted from hops and

incoporating a greatly accelerated haze-prevention method, which is economical.While drastically shortening the process, this and the other stages have been beneficial rather than otherwise to beer flavour.

I should like to say how much I appreciatethe great honour which the Council has doneme in awarding me the Horace Brown Medal;such a commendation is deeply and indelibly

affecting.I realize at this timeas everyone in thissituation musthow much 1 owe to the manycolleagues who have taken part in all thedifferent aspects of my work. Consequently

1 should like to say how much I have appreciated working with them and how much I

wish to thank them.I would also like to pay tribute to thosewho have provided inspiration for my work.Among them, outstandingly, is HoraceBrown himself. His scientific work went farbeyond brewing and I first learnt of aspectsof his scientific findings before I knew of his

connection with brewing. I have sincebecome familiar with all his work and, as aresult, I wholeheartedly join other medallists

and many of his contemporaries in payingtribute to the outstanding nature of his work,to its wide range and to its deep insight. InBrown's day it was right and proper to pay a

tribute in Latin and his contemporaries mustsurely have said of himNihil tetigit quod nonornavitHe touched nothing without en

hancing it.

Brown succeeded so well in brewingscience because, for this, it is necessary tocross the dividing lines between the neat subdivisions made in the academic world. He

had had only a year's training as a chemist,but it was sufficient to enable him to teachhimself or discover for himself whatever wasgermane to His purpose. Further, in utilizing

this knowledge he showed brilliant perceptioncoupled with rigorous analytical thinking

both in biological and in chemical matters.To me it seems, however, that in all thetributes paid to him no great stress has beenlaid on one of the main focal points of hisideas and his workhis conviction of thegreat and special importance of the nitrogen

compounds of wort and beer.It appears from his remarks that this conviction was inspired by Liebig's dictum thatfermentation and putrefaction were producedby nitrogenous substances. This was a concept which spurred Brown into concentratedefforts over the last 20 years of his very active

working life. In that time he attainedremarkable success, bearing in mind the

almost complete absence of suitable methodswhen he started. To remedy this he inventedmethodsnot many people know, for instance, that he discovered the nitrous acid

Vol. 77, 1971]method for measuring free alpha aminonitrogen long before Van Slyke, who gets the

credit in the textbooks. Brown's interest andenthusiasm awakened echoes, and about a

year after his death, in February, 1925, theInstitute of Brewing published a smalladvertisement in Nature for a scientist tostudy the nitrogen compounds of barley. I

had the honour to be appointed to that postand the nitrogen compounds of barley, malt,wort and beer have been an outstandingconcern of mine ever since.

Brown himself commenced as a brewer inBurton in 1866, and, after the completion of50 years work (that is in 1916), he reviewed

the situation in his Reminiscences of50 Years'Experience of the Application of ScientificMethod to Brewing Practice.*0 Now it is some

50 years further on in time and it seems rightand proper to ask what the scientific methodhas done for brewing in the last hundredyears. This, I therefore feel, must be thescope of my Conspectus of Brewing Progressa review whichlike Brown'smust be of

a somewhat personal nature.Brown records that in 1866 there waslittle if any scientific knowledge which could

be of help to a brewer in avoiding or escapingfrom any difficulty in brewing. Existingbooks on the subject were devoid of clear or

helpful ideas and, as he said, "the explanationof any occult phenomenon was found in themysterious agency of electricity, just asphysiological phenomena were explained byrecourse to a supposed 'vital force'."

The devastating inadequacy of the theorieswas endorsed for Brown by the occurrence ofa brewing disaster during his first year in the

Industry. He was later able to explain thevisitation as a severe attack of Lactobacilluspastorianus, but, as he says, "the rigid rules

laid down and sanctified by experience andtradition proved useless as a help to Brewers,who were, therefore, powerless in the face ofa catastrophe." As Brown records, it was

Pasteur's subsequent work and his ownwhich led to the recognition of the cause ofthe trouble; and it was Brown, with hisforcing tray and his acid treatment of

pitching yeast, who put the means of detection and of control in the hands of brewers,who, up to that time, had been forced tobrew only in the winter montlis, as the sole

means of avoiding unending serious trouble.It is perhaps not generally recognized nowhow overwhelmingly serious this trouble was

BISHOP: HORACE BROWN MEMORIAL LECTURE 13at that period and it was in consequence that

Brown devoted much of his "Reminiscences"to Pasteur's, Hansen's and his own studiesinto the microbiological causes of the brewing

troubles. Even before the appearance ofPasteur's Etudes stir la Biere, Brown hadlearnt to recognize under the microscope thechief brewery spoilage organisms, such as

Lactobacillus pastorianus, and he was quickto put the findings into practice.

It is important to realize that it was thistotal preoccupation with microbiologicaltroubles which directly inspired Brown'sinitial interest in the nitrogen compounds, forhe considered that excess of nitrogen compounds (especially in some seasons) mightpredispose beers to microbiological attack.

He argued that such predisposition must comefrom the nitrogen compounds which remainpermanently soluble in the wort, and hetherefore worked as Director of the Guinness

Research Laboratory from 1903 to 1906 andsubsequently on these compounds. He had

the idea that if he found significant ones theycould then be traced back to barley. Thescheme on which I started in 1926 was theopposite: that of studying first the nitrogencompounds of barley, then of malt, wort and

ultimately those of beer.Before mentioning some of the results, Ishould like to revert again to the last century.

It was then that botanists were fascinated bythe beauty and variety of the external formsof plants and they collected and classified on

this basis, but it was Brown, a self-taughtbotanist, who led the way in taking the

understanding inside the plant by his brilliantstudies with G. H. Morris of the physiology ofgermination in barley.

Since then others have carried the analysisdeeper still. We know that each individualplant or animal starts life as a single celland in that cell are transmitted all that is

necessary to make the mature plant oranimal exactly like its own kind and differentfrom all other kinds. The explanation, wenow know, lies in the chromosomes of thenucleus of each cell of the organism. The

units of inheritance are the genes which arestrung like beads along the chromosome, and

the recent developments in their study are afascinating story. Crudely, each gene is inits turn an individually constituted nucleicacid string which is responsible for buildingan individual sequence of amino acids to

form a specific protein. This can be an

14 BISHOP: HORACE BROWN MEMORIAL LECTUREenzyme controlling a particular function in

the cell and so ultimately affecting theexternal form of the particular plant or

animal.In order to function correctly, the aminoacid sequence in a particular protein has to beto an exact pattern. The classic illustrationis the adult-type human haemoglobin, whichin virtually all individuals has identical

amino acids in identical positions throughoutthe molecule. In a few exceptional individuals one molecule of valine is inserted

instead of glutamic acid at one position ineach of the two /3 chains: that is two aminoacid units have been changed out of a totalof 574the result is to upset the haemoglobin

functioning so that these individuals suffer aserious defect of metabolism called "sickle

cell disease."So the hereditary basis of the cell is amechanism of extreme regularity and extreme precision at the submicroscopic level.And, to come back to our 19th century bio

logists, it is this regularity which leads

0-30

S 0-20 -

tC 0-10 -s

O0-1 0-2 0-3 0-1 0-5 04 0-7Grams of total nitrogen per 1,000 cornsFig. 1.Proteins of Archer barley, as a function of

total nitrogen. Salt-soluble N:-n-; Glutelin-N: - A-: Hordein-N: -O -

ultimately to the external regularities in theform of the plant or animal. It follows thatthe stages in between must also be based onsimilar strict regularities; and some 40 years

ago I was able to demonstrate regularities inthe amounts of the proteins in barley and inwheat.4 >6'6 In the light of present-day findings this regularity now seems inevitable.The regularities are most evident when

quantities are calculated per corn (or perthousand corns) and in Figs. 1 and 2 the

[J. Inst. Brew.quantities of nitrogen compounds are calculated per 1000 corns. Corresponding analysesfor wheat proteins by Grewe*8 on a dry weightbasis when plotted as in Fig. 3 show similarregularities.

0-30

0-20 -

o-io -*3

IC

0 0-1 0-2 0-3 0-4 0-S 04 0-7

Grams of total nitrogen per 1.000 cornsFig. 2.Proteins of a six-row barley (F 112) as a

function of total nitrogen. Salt-soluble N:-D-; Glutelin-N:-A-; Hordcin-N:-O--

Since the time of that work, techniqueshave improved enormously, and what perforce had to be treated as an individual pro

tein we now know to be a class comprisingmany individuals. However, the general

principle still holds and it seems to be thatthis link between the submicroscopic and themacroscopic worlds of biology may beworthy of further study by the elegantmethods now available. Predominantly, recent studies by these methods have been

qualitative, but very recent developmentshave offered the possibility of quantitativeassessment also, so that it should be possible

to study protein regularity using quantitativemeasurements of truly homogeneous individual proteins.

I would not, however, belittle in any waythe qualitative search for individual proteins.Numerous techniquessuch as gel filtration,column chromatography and various types ofelectrophoresisare now available for theseparation and purification of individual pro

teins. The best technique for precise identification is by immuno-electrophoresis andconsequently I have pressed strongly for theformation of a Sub-committee of the E.B.C.Haze Group and for the prosecution of itsworkwhich has led to the issue of the

E.B.C. Reference Serum.3 In the form

B W R M

m^jaWtoHHMJy

Fig. 4.Disc clectro|)horesis of the basic proteins of different cereals. li = barley; \V wheat;K = rye; (1 oats; M = maize.

B

'-,:.-

Disc elcctropluircsis of the basic proteins of five barley varieties.(' ^ Kunia; D ^ Cambrinus; K - Pirkka.

A = Haider; 13 In^rid;

Vol. 77, 1971]shortly to be published this provides anextraordinarily sensitive means for the identi

fication, of 26 of the chief proteins of barley,which, therefore, serve as markers for the

recognition of other barley proteins.

BISHOP: HORACE BROWN MEMORIAL LECTURE 15

Glladln

Glutenln

Salt-soluble

9 10 II 12 13 14 15Total protein (n x5-7) as percentage on

dry matterFig. 3.Regularities in the protein proportions in

wheat." Salt-soluble-O-: Glutcnin -&-; Gli-adin -O-.

Science is essentially a building upwardson the firm accomplishments of one's predecessors, but in much recent plant proteinwork each researcher or group has assigned a

set of names, while the next has givenanother, unrelated set, so that the findingssink, in time, leaving little trace. With the

help of the reference serum, purity and identity between laboratories can now be safelysettled and the findings can be built upon.

The proteins are important because theyare the essence of the identity of the plant.

How far can one utilize this and identify theplant or animal from its proteins? The

answer to this is that widely different types(for instance the edible fish of commerce) canreadily be distinguished when their proteins

are separated in an electric field and stained.41The different cereals of commerce are all ofrelated genera, but Mikola44 has shown distinct differences in their pattern of proteins

(Fig. 4), while Ewart has shown differencesbetween the different species of wheats.48

Ultimately we may hope that proteinresolution by this method will be vastlyimproved, for it may be necessary to resolve

several thousand proteins. This, if it couldbe achieved, would give us fundamentalknowledge of what consitutes a variety at themolecular level and, at the same time, wouldgive us a badly needed means of quicklyidentifying varieties. Already, in the workof Mikola4* there are indications that thedifferentiation of at least some barley

varieties is possible and his results here areillustrated in Fig. 5.

Reverting to my old quantitative work, Ishowed that the quantities of the groups ofproteins varied with the variety and showed

too that the carbohydrates exhibit ananalogous regularity.*1 This can be summarized briefly in Fig. 6. which shows that, withincrease of total nitrogen or total carbo

hydrates the rate of increase of cell proteinsor carbohydrates falls off and that the storage

proteins or carbohydrates increase correspondingly and regularly the proportion varying with, and being characteristic of, thevariety.

Reserve proteinsor carbohydrates

///J.

*/ /Ifi /t // "/ ^ l-ro*

"Cell" proteinsor carbohydrates

' Total protein or carbohydrate per corn

Fig. 0.Generalized diagram of carbohydrate andprotein relations and inter-relations.

The importance of this is to negative theidea current in Brown's day that the protein

proportions might be violently changed byweather or other external conditions andinstead this regularity makes us look else

where for explanations of abnormalities ofbehaviour in brewing or fermentation. It is,therefore, outmoded to suggest that barleysmay differ in the "quality " of their nitrogen

compounds, since the "quality" is regular and

16 BISHOP: HORACE BROWN MEMORIAL LECTUREis fixed by the total quantity of nitrogen and

the variety.Then too the varietal regularity in carbohydrate proportions forms the basis for theprediction of extractwhich still seems to beserving a useful purpose after some 40years.1'8'8'10-83'32 Besides the prediction ofextract from nitrogen content and thousand

corn weight, I introduced a less popular prediction from nitrogen content and "insoluble

carbohydrate," which is independent ofvariety and has proved of use in barley

breeding.10 The two types of prediction areillustrated in Figs. 7 and 8.

105 -

Nitrogen content (%)Fig. 7.Relation between nitrogen content and

extract for different varieties. All extractshave been corrected to that for 38 g 1000-corn

weight. Standwcll (A); Spratt-Archer (D) andPlumage-Archer (); B 244 (); F 112 (X);Atlas (O) Mariout (A).

What is perhaps less obvious about thevalue of prediction is that the extract yieldin this country has improved considerably

in the last 40 years and tliis may be partlythe result of having a predicted standard as aguide. The regular varietal differences in

carbohydrate composition have implicationsfor the breeding of malting barleys.

For this early work I was based at Rotham-sted Agricultural Experimental Station and

there the main work of the Station gave me

QJ. Inst. Brew.an acute interest in all agricultural problemsconnected with barley. Why was nitrogencontent high this year and low thatwhatcontrolled yields and how far could they beconsciously controlled?

The data for such studies were there atRothamstedfrom the hundred year oldclassical experiments on Hoosfield and from

the Woburn plots,7 while in addition therewas much further information from the thencurrent Institute of Brewing nationwideseries of barley manuring trials. These had

been inspired and organized by the perspicacious and energetic director of Rothamsted at that timeSir John Russell. In

addition to organizing the Institute trials, hehad arranged and held Symposia to convey thefindings back to farmers, since there was, atthat time, no other organization to do this.The findings were given more permanent formin a comprehensive 10-years Report which he

and I produced in 193346where there isstill much with relevance to present-day

agricultural problems. Previous advice hadforbidden nitrogenous fertilizer as inevitablybound to increase nitrogen content and

lower quality; but one of the essential findingsof this Report was that, correctly used, nitrogenous fertilizers could be of benefit to

yield, without damage to quality.Russell successfully promulgated the findings of the Institute experiments in the yearsbefore the war, and it is my strong convictionthat the resulting increased barley yieldswere of great benefit to this Industry and to

this country. Especially was this so whenthe country was plunged into war, and themassive barley imports suddenly stopped

leaving us to starve or survive on the homegrown supplies.

The higher yields from sound manuringwere one factor in helping our agriculturalsubsistence, and another of crucial importance was the economy of manpower effectedby the wartime change to combine harvestingand farm drying. This meant a great gain

to farmers but an agonizing break with allbrewing traditions, and there wereconsequently many doubts and misgivings. Among thedifficulties, the combined grain became avail

able for market immediately after harvest,instead of after several months in stack,

which gave germination problms and troublefrom high moisture content.13.,.,.,*.

To explain the baffling phenomena whichoccurred after harvest I introduced to malting

Vol. 77. 1971] BISHOP: HORACE BROWN MEMORIAL LECTURE 17

1

'Ia6 _,

1-4

Nitrogen

Fig. 8.'Extract prediction: 2-row plus 6-row results (giving alternate cases only in 2-row)E = 134-7 - 9-78 N - 204 I(E = Extract; N = nitrogen content; I = Insoluble fraction).

the concept of dormancy of the germ throughoxygen deprivation, and tlus has helped in

the proper management of these barleys.Damage to germination from storage at high

moisture content occurred frequently in theearly days of combining; while damage from

high drying temperatures (especially on verymoist barleys) also occurred. I showed that

both types of damage could be quicklydetected by staining methods17 -18>22 and

introduced a specially simple and rapid testusing iodo-nitro-tetrazolium.87

At this period of time, explaining thefarmers' viewpoint to the Industry or the

Industry's viewpoint to farmers was not easy,but I am happy with the degree of reconcilia

tion of views which has occurred since.As an outcome of this work, the degree of

dormancy found under any particular set ofconditions was shown to be a characteristicof each variety, and, up to an optimum, themalting quality of a variety improves as the

tendency to dormancy is lower. Indeed thismay well be the major factor which differentiates the malting value of barley varie-

ties.17-18-28 At one extreme the dormancycan be too low so that the variety oftengerminates in the Reid. Sometimes this

leads to overt sprouting which has long beenknown, but often only slight growth of therootlet has occurred which can only bedetected in longitudinal section. I drew

attention to this and called it "pregermina-tion."lfl It is important because, while thegrain may be alive at purchase, it is liable

to die in the early stages of storage. At the

18 BISHOP: HORACE BROWN MEMORIAL LECTUREother extreme of germination behaviour arevarieties which only germinate and malt wellafter very long storage and hence are of littleuse for malting. Comparative results forvarietal dormancy are illustrated in Fig. 9where the whole range of behaviour can beseenfrom Scotch Common, which readily

pregerminates in the field under English conditions, to Hordeum spontaneum, which is

unmaltable until after one to two yearsstorage.

Under practical conditions the degree ofdormancy of a sample at malting may not be

known, but the practical consequences will be

[J. Inst. Brew.evident from the malt analysesin the fine-coarse extract yield, in the cold waterextract figure and in the index of modifica

tion,9 which will improve with decrease indormancy, e.g., after storage of the barley.

In consequence of these considerations it isimportant to select new varieties of barley

at the early stages of breeding so as toobtain optimal dormancy for the region, aswell as also selecting at an early stage forother brewing requirementssuch as highextract yield. A programme and method fordoing this were proposed in 1954*8 and havebeen widely followed since.

100 -

70

sSi

8>S 50

30

Scotch common

7030 -to JO 60

Time of germination (hours)Fig. 9.Relative germination rates of varieties of barley.

80

Vol. 77, 1971]The various aspects of this work as theybear on the process and problems of maltingwere summarized in a paper entitled A

Scientific Approach to Malting.19 Most of thesuggestions in it, including analytical appraisal of barleys, now seem to have been

adopted.Contemporaneously with this work I hadcarried forward studies of the nitrogen compounds in brewing. In agreement with theprinciple of regularity, which I enunciated asa result of the early protein and carbohydratework,8 the permanently soluble nitrogen wasfound to be in a fairly regular relationship tothe total nitrogen content of the barley.9 Isuggested that such divergences as there were

provided a measure of the protein modification in malting and this has been generallyaccepted. In its turn, the assimilable nitrogen was measured and found to be fairlyregularly around 45% of the permanentlysoluble nitrogen.20

This meant that the work had reached astage when it could be linked with Brown'swork on the nitrogen compounds of wort and

beer. The joint findings agree to give adefinite preliminary picture of the nitrogencompounds of wort and beer.

Some 25 years ago I defined a true proteinas having a molecular weight over 17.00018

and this is closely in line with moderndefinition. Accepting this, we can say that

there is no true protein in boiled, hoppedwort or in beer, so one should carefully avoidreferring to the "proteins" of beer: this viewis not original for it was held by Brown in

1907.38 There is a slight modification in thatI introduced a sharply specific method formeasuring true protein and tlu's methodshowed traces in some beers." Substantially,

however, there is none. Therefore, althoughit can be shown by immunology that theyhave originated from known true proteins,the nitrogen compounds in beers are belowthe protein size level. There may appear tobe a contradiction here with molecularweights derived solely on a physical basis,

but it must be remembered that such molecular weights are, at least in many cases, thevalues for a protein-polyphenohc or othersimilar complex, not the molecular weight of

the uncomplexed nitrogen component.To measure the complexity of the nitrogencompounds themselves, Brown introduced achemical measurement of the ratio of free

amino nitrogen to total nitrogen, as a measure

BISHOP: HORACE BROWN MEMORIAL LECTURE

exactly analogous to the reducing power ofcarbohydrates. I consider this to be a mostvaluable ratio, wlu'ch has unfortunately notbeen taken up in recent work. I, therefore,fall back on Brown's work and my own togive a semi-quantitative picture of wort and

beer nitrogen compounds. My ownmethod*4^ was to add phosphotungstic acid

to a sample of wort in numerous, regularlyincreasing doses, starting with very small

additions and ending with a very high finalconcentration. The initial small doses precipitated the most complex nitrogen compounds and then compounds successivelylower in complexity were precipitated until

the final precipitates contained compoundsof around tripeptide size. Tested on a seriesof worts, all snowed a similar pattern butquantitative differences. In other words

this method had provided a sensitive andscientifically-based means for fractionating

the nitrogen compounds of worts and beers;and this method had shown that order and

regularity persist into these stages of theprocess. The type of pattern found in sixworts is illustrated in Fig. 10.

Phosphotungstic acidfractional additions in grams per 100ml of wort

0-15 0-45 0-75 145 1-35 1-45 1-95 2-25 2-55 2-8530 [

20 H \ Callfornian malt 1936 A; vVw \f

Callfornian malt 1939

o-o-o-o-o-o-o

(-15 0-90 2-25 4-40 *75 9 90 1365 18-0 U 95 28 50

Fig. 10.Fractionation of wort nitrogen compounds with phosphotungstic acid.

20 BISHOP: HORACE BROWN MEMORIAL LECTUREThe pattern allows an approximate estimate to be made of the amounts in the differ

ent classes of compounds and this estimatewas in good general agreement with findingsfrom his 1903-06 work published by Brown

as the Nitrogen Question in Brewing, Part J.38This is shown in Table I giving comparativeresults.

This Table gives a crude picture, but themeans exist today to make it much more

exact. Indeed it would be possible now toisolate and to work out the amino acidsequence of each constituent. My own view

would be, however, that the exact structureof the complex nitrogen compounds is not ofthe first importance and what matters forbehaviour in beer is the type of acidic sub-tance attached to the nitrogen compounds

that is polyphenols, isohumulones, melan-oidins and so on.12

Astoundingly it was Brown as long ago as1913s9 who demonstrated that the organicmaterial which deposited from worts andwhich formed haze in beers, was a unique

combination of two-thirds protein and one-third tannin. During this century the needfor freedom from non-biological haze hasgradually grown in intensity as the intensity

and frequency of biological haze has diminished, but it was not until the formation of

the E.B.C. Haze Group in 1956 that Brown'sfinding was fully confirmed and furtherstudied. Since then, of course, the extension

of this work has given us the means of controlof the haze problem, and I have recentlydescribed one method of effectively accomplishing this.32 Head formation and persistence are related phenomena, and we can

look to further developments here.

[J. Inst. Brew.Brown formed the opinion that the complexnitrogen compounds are involved in yeastnutrition, but my work and that of othersshowed that yeast feeds only on the simplenitrogen compounds. He also feared thatexcess assimilable nitrogen might promoteinfection, but Mr. Whitley and I in unpublished work found that infection in fermenta

tions developed much more readily in conditions of nitrogen deficiency. Furthermore,Whitley and I showed that in an all-maltwort the assimilable nitrogen was aboutoptimal for attenuation.37

Therefore, while the nitrogen compoundshave been demonstrated to be of much value,

they could not explain some malevolentaberrations which were still being found in

brewing, even after the consequences ofmicrobiological infection had been understood. Among these other difficulties, for

the first part of the present century, thereiterated complaint was that of "yeastweakness,"47 which was often attributed tonitrogen deficiency. Yeast weakness I found

usually meant a sticking, incomplete fermentation, although it could, in some breweries,mean the opposite. An explanation camewhen I cooled hopped wort and allowed it tostand (under sterile conditions) so that thewort sediment settled to the bottom. The

top bright half was then compared in onefermentation in a glass cell with the turbidbottom half in another. From the bubbling,

the turbid wort appeared to ferment muchfaster, but in fact it was the clear half whichattenuated faster and further. So thematter was studied to resolve the paradox.This led to an interesting exercise in physical

chemistry, and so to the elucidation of a

TABLE IIndicated Nitrogen Compounds in Worts and Beers from the Results op

Brown" and Bishop"

Designationofnitrogencompounds

ProteinsProteoscs (Albumoses)Peptones ..PolypcptidesSimple peptides and free a amino-

acids

Worts

Proportion oftotal nitrogen

Brown

02030

42

Bishop

020-26

16-2016-25

^36

% of freeamino nitrogen

Brown

4-611-20

Bishop

2-45-1515-30

30-100

Beers

Proportion oftotal wort

nitrogenBishop

020-26

15-2010-16

0

Vol. 77, 1971]phenomenon which 1 called "sediment ac

tion." A full exposition here would take toolong, but, if they have not come across thework, I would recommend a study of sediment

action to brewers who still wish to fermentbatchwise.11'36 The effects disappear instirred fermentations.

There is, however, another importantsource of yeast weakness which affects both

batch and continuous fermentation, and thiscame to light in my studies of the nutritive

properties of wort.As I have said, I had already studied nitrogen nutrition of yeast and considered it

neither too high nor too low in normalworts. I had investigated, with Dr. Rainbow,

possible "bios" (that is yeast vitamin)deficiencies39 and had found again that

supplies were adequate in normal worts.However, before I went to Watneys in 1946I had already obtained evidence of a definitemineral deficiency in worts. At Watneys Iwas somewhat nonplussed when I found that

tests had to be made in 700 barrel (1000hectolitre) vessels. Fortunately these testswere remarkably successful and by 1951 Mr.Cory and I were fully convinced that breweryworts can be deficient in minerals for yeastnutrition. Furthermore, we were convinced

that my original observations had beencorrect and this deficiency was overwhelmingly that of one element, required only in frac

tions of a part per millionzinc.These traces of zinc are undoubtedlyrequired in the prosthetic group of important

yeast enzymes such as alcohol dehydrogenaseand for a similar reason zinc is essential to

human beings also. Subsequently to thiswork, the greater part of the yeast-zincstory in brewing has been elucidated andpublished by other workers; but none, Ithink, has had a more dramatic result thanour first large-scale test in 1951 in two 700-barrel vessels, where the stimulated fermentation gave a yeast head some eight feet higherthan that of the control, and this as theresult of the addition of only three quartersof a part per million of zinc. Incidentally,

yeast is so avid for zinc that, at the end ofthe primary fermentation all traces areremoved from the beer.

The deficiency must mean that zincphosphate or phytate has an extremely lowsolubility in worts and this in turn explainswhy, in some circumstances, wort sediment

may have a beneficial effect apart from

BISHOP: HORACE BROWN MEMORIAL LECTURE 21"sediment action." The results of oneearly experiment are shown in Fig. 11.

So it was in the end, not nitrogen compounds, but two entirely different causes"sediment action" and the stimulatory effectof minute traces of zinc which I had found to

be the scientific explanations giving practicalcontrol over the apparently irrational diffi

culties formerly occurring in brewing.I went on from this point to other studiesin brewing unconnected with nitrogen compounds. Brown had studied the diastaticaction of dry hops but not other aspects ofthis interesting flower. I found hops anexhilarating study.

As I have pointed out previously30 lupulingrains contain all that is of benefit to brewers

and offer great advantages in the separatedstate. However, the conjunction of the

resins and the essential oils in the grainsmakes them exceedingly sticky and so makesseparation extremely difficult. This was

clearly a chemical engineering problem and Iwas fortunate both to have had some trainingin this field and to have had experience indesigning other plants of original types for

liquor treatment, pure yeast production andso on. Therefore, the lupulin problem when

it came was another challenge and I was ableto design a plant which worked effectively

(British Patent 961, 506). This has enabledus to shorten drastically and to improve thedry hopping of beers. The possibilities ofextracting and using lupulin for the bittering

of beers are under development.Perhaps, however, my greatest satisfactionin this field came when I was given theopportunity to design and bring into opera

tion plants for continuous fermentation suchas those described in a recent paper.31

The comparison of fermenting rooms asthey were in 1868 with the continuous fermen-tors shown in that paper may perhaps epitomize the contrast between the end and thebeginning of this Conspectus. At the beginning, the external appearance of brewerieswas solid and impressive, and it is natural tovenerate them and the plant in them, for theyrepresent the outcome of a long tradition.

However, this tradition knew nothing of thescience of microbiology, so the construction

was such as to provide unsterilizcd and oftenunsterilizable pockets of infection. For instance, mash tuns were so designed as to lead

to development of wort bacteria in thetroughs and underbacks, and, although this

22 BISHOP! HORACE BROWN MEMORIAL LECTUREinfection would be killed by boiling, some of

the metabolic products would probablyremain. In addition, reinfection after boiling

was likely, if not inevitable. This couldoccur on the open coolers, most probably

[J. Inst. Brew.from wort residues left in the unevennesses of

the cooler floors. Again, for similar reasons,refrigerators of both the vertical and horizontal types were probable sources of infection. Although we may view coolers and

3

4-5

Control

100 120 140

Yeast cropControl 471bStimulated 5-5lb

.Aerated/ . Eased and aerated

SkimmedEasedSkimmed-

Liquor onLiquor on full

Liquor on

20 40 80Hours

100 120 140

Control

StimulatedSafe pH

20 40 a 80Hours

100 120 140

Fig. 11.Effect of 0-70 ppm of zinc on a top yeast fermentation.

Vol. 77, 1971]refrigerators with nostalgia, they are for themicrobiologist a problem that sometimesbecomes a nightmare.48 Moreover, even if

microbiological hazes are avoided, the traditional metals of constructioniron andcopperare precisely the two which promote

non-biological haze.For the microbiologist, even more than thetraditional designs in copper, wood is asource of worse nightmares, for infection in

the grain of the wood is virtually unsteriliz-able, and in 1866 wood was the traditionalmaterial for fermenting vessels and for thesubsequent lengthy storage of beers, so it

constituted a major but unrecognized hazard.Now, we have suitable metals and suitablesterilizable designs for brewing plant whicheliminate much of the danger oT infection andsome of the danger of non-biological haze.

Meanwhile, scientific studies in other directions have given us means of eliminatingmany of the other brewing difficulties of thelast hundred yearsdifficulties such as yeastweakness and other remaining causes of non-biological haze.

In breweries that have been built recentlywe are already becoming accustomed todrastically revised appearances and I envisage

further changes to implement present capabilities, especially in the fermenting and laterstages.

Therefore, with new plant and revised, butsound processes which realize the potenti

alities we have today, it may well be thatfuture brewers will know of the difficulties of

the last hundred years only through textbooks.

If 1 have in any way contributed towardsthis possibility, the work has been to me agreat pleasure, while it has been a great

privilege to follow in the work which Brownso magnificently started.

References1. Anon., Journal of the Institute ofBrewing, 1958,

64, 469.2. Anon., Journal of the Institute ofBrewing, 1905,

71, 470.3. Anon., Journal of the Institute of Brewing, 1967,

73, 381.4. Bishop, L. R., Journal of the Institute of

Brewing, 1928. 34, 101.5. Bishop, L. R., Journal of the Institute of

Brewing, 1929. 35, 310.6. Bishop, L. R., Journal of the Institute of

Brewing, 1930, 36, 330.7. Bishop, L. R., Journal of the Institute of

Brewing. 1930. 36. 352.

BISHOP: HORACE BROWN MEMORIAL LECTURE 238. Bishop, L. R., Journal of the Institute of

Brewing, 1930, 36, 421.9. Bishop. L. R., Journal of the Institute of

Brewing, 1931. 37. 345.10. Bishop. L. K., Journal of the Institute of

Brewing, 1934. 40. 75.11. Bishop, L. R.. journal of the Institute of

Brewing, 1938, 44. 00.12. Bishop, L. R.. journal of the Institute of

Brewing. 1943. 49. 16S.13. Bishop. L. R., Journal of the Institute of

Brewing. 1944. 50. 100.14. Bishop, L. R.. Journal of the Institute of

Brewing, 1944, 50. 224.15. Bishop, L. R., journal of the Institute of

Brewing. 1945,51. 127.16. Bishop, L. K.. journal of the Institute of

Brewing, 1945. 51. 166.17. Bishop, L. R.. Journal of the Institute of

Brewing, 1945, 51, 215.18. Bishop, L. R.. Journal of the Institute of

Brewing, 1940, 52, 273.19. Bishop, L. R.. Journal of the Institute of

Brewing, 1947. 53, 80.20. Bishop, L. R.. Journal of the Institute of

Brewing. 1947. 53. 129.21. Bishop. L. R., Chemistry and Industry, 1947.

779.22. Bishop, L. R.. Proceedings of the European

Brewery Convention, 1947, 8.23. Bishop. "L. R.. Journal of the Institute of

Brewing. 1948, 54. 330.24. Bishop, L. R.. Journal of the Institute of

Brewing, 1949, 55, 147.25. Bishop, L. R., Proceedings of the European

Brewery Convention, 1949, 244.20. Bishop, L. R., Journal of the Institute of

Brewing, 1954, 60, 130.27. Bishop, L. R.. Journal of the Institute of

Brewing, 1957, 63. 516.28. Bishop, L. R.. Journal of the Institute of

Brewing. 1958. 64. 484.29. Bishop, L. R., Revue International de Brasserie

et Malterie. 1962-63. 55.30. Bishop, L. R., Proceedings of the American

Society of Brewing Chemists, I960. 64.31. Bishop, L. R., Journal of the Institute of

Brewing, 1070, 76. 172.32. Bishop, L. R., Proceedings of the American

Society of Brewing Chemists, 1970.33. Bishop, L. R., & Day, F. E.. Journal of the

Institute of Brewing. 1933, 39, 545.34. Bishop. L. R.. & Mane, D., Journal of the

Institute of Brewing, 1934.40, 62.35. Bishop, L. R., & Rainbow. C, Journal of the

Institute of Brewing, 1939, 45.'33.30. Bishop, L. R.. & Whitley, W. A., Journal of the

Institute of Brewing, 1938. 44, 73.37. Bishop. L. R.. & Whitley. W. A., Journal of

the Institute of Brewing. 1940, 46. 391.38. Brown, H. T., Journal of the Institute of

Brewing. 1907, 13, 169.39. Brown, H. T., Journal of the Institute of

Brewing. 1913. 19, 84.40. Brown, H. T., Journal of the Institute of

Brewing. 1910. 22. 267.41. Cowie, W. P.. Journal of the Science of Food

and Agriculture, 1908. 19, 220.42. Ewart, J. A. D., Journal of the Science of Food

and Agriculture, 1969.20, 221.

24 THOMPSON AND CAMERON: DIFFERENTIATION OF UUEWING YEASTS [J. Inst. Brew.43. Grcwc. E.. & Bailey. C. H.. Certal Chemistry, Institute, of Brewing. 11)33. 39. 287.

1027, 4, 230. 40. Siau, R. L..' Journal of the Institute of Brewing.44. Mikola. j.. Annalcs Academiae Scicnliarum 1900. 12. 118.Fennicot, Ser A. II Chctnica lflO5. 130, 1. 47. Siau, R. L.. & Hodson. A. K.. Journal of the45. Russell, E. J., & Bishop, I.. R.. journal of the Institute of limiting, 1009, IS, sec p. 80.