The Technical Evolution of the Belgian Brewery During and After the War


The following paper was read and discussed:—


By Professor J. de Clerck

In Belgium during the present century top fermentation beer has been steadily supplanted by lager and draught by bottled beer.  During the recent war gravities fell to 1,009-1,019 and beetroot up to 50 percent, was effectively employed when sugar and malt supplies ran low. Post-war conditions have brought high taxation, reduced consumption and intense competition.

In malting, the main development has been the careful restriction of respiration towards the end of the growing period, the Saladin system being still the vogue.  Other devices for reducing malting loss are being investigated.  The work of Govaert, which has led to possible economies in hops, is concerned with the artificial transformation of humulon into the more soluble and bitter  isohumulon, thus avoiding loss through the formation of non-bitter resins.  Pure culture top yeasts have often been found to acclimatize themselves to worts of a given gravity, even a very low one, and the occasional use of a stronger wort to nourish the yeast is of doubtful benefit.

Problems in conditioning and maturing of beer are discussed and a description is given of a new patent cask which can be filled without loss of gas or exposure to air.

It is intended to give a description of the technical evolution of the brewery in Belgium, but it will be useful to say, beforehand, a few words about the economic evolution of the Belgian brewery, which influenced greatly its technical development.

Before the first world war, there were many breweries in Belgium, more than 3,000.  Beer consumption was very heavy, more than 200 litres per inhabitant per year (44 gallons), Almost exclusively top fermentation beer was brewed and sold in barrels.  A few breweries started making lager beer; their products were more regular; they gained in the favour of the public and soon these breweries grew to become very large ones.  In between the two world wars, two-thirds of the breweries disappeared and it was chiefly the bottom fermentation breweries that extended.  The consumers lost their taste for the flat draught beer and the top fermentation brewers readjusted their methods by conditioning their ales; so doing they succeeded in competing successfully with the lager type.  The flat draught beers disappeared completely.  Beer prices going up steadily because of continuous rise in taxation, the consumption per capita fell to 175 litres (about a barrel).  The sale of bottled beer grew continuously.

During the last war beer became necessarily very weak as the shortage of malt was severe, gravities ranging from 2-4 to 4-7 per cent. extract (sp. gr. 1-009-1-019).  The small quantities of malt brewers had at their disposal were not sufficient to provide these gravities and it was necessary to look for other materials.  At first, sugar was used, but these supplies soon ran out and finally beetroot was the only material available.  The beet was cut in strips, dried on a kiln and then ground, so as to get grits or flour.  For those light beers, beetroot gave reasonable results.  A simple extraction was sufficient and very often beers were brewed with 60 per cent, malt and 50 per cent, beetroot.  Fermentations were good and the foam on the beer was firm and persistent.  Even today, certain breweries still use beetroots, because this material gives a good head, perhaps through the pectin it contains.  This pectin often produced a persistent turbidity in the tanks, but the flavour of the beetroot was not noticeable, because the beers were so light that they did not, in fact, contain much of this material.

In order to give a pleasant flavour to these war beers, the brewers used chiefly sweetening products, colour and hops, which were still plentiful, but the latter could easily produce an astringent taste in the light beers.  Vinegar was also used. In Belgium the sour beers, like Lambic, still meet with a certain favour and blendings were made of Lambic with ordinary beer.  As there was no Lambic left during the war, beer-vinegar was manufactured to take its place.  Notwithstanding all these efforts to keep one flavour, if nothing else, in the beer, the consumption dropped to one half of the pre-war figure.

After these innumerable difficulties with which the brewers had to cope, all their hopes lay in the return of peace; but it turned out to be a deception.  When beer came back to its normal gravity in the beginning of 1946, consumption went up, but the beer was too expensive, because the State had naturally raised the taxes and cereals remained very dear. The total of brewing materials used dropped to 70 per cent, of the quantities of 1938.  Since, in Belgium, the excise duties are calculated on the weight of materials used, they are the only correct basis to appreciate the beer consumption.  The beers remained, however, slightly lighter than before the war, so that it must be said that the consumption fell by 25 per cent.  The reasons for this setback are naturally much discussed among brewers.  The opinion is often expressed that the habits of the population have changed.  In fact, more coffee, fruits and chocolate are imported into Belgium than before the war.  Nevertheless, the principal cause must be the price of the beer, which is too high; indeed, considering the purchasing value, in glasses of beer, of the workman’s salary, it will be found that it lost exactly one-quarter since before the war.

This fall in consumption is the cause of a grave economic crisis in the Belgian brewing industry. The means of production being so important, and competition so strong, each brewer tries to keep his customers, selling the best possible quality at the lowest price.  It is this crisis which stimulates the technical developments in the breweries; they are dominated by the necessity to manufacture at a lower cost without impairing the quality.  Some of the innovations designed to achieve this will now be examined.

The brewing methods of the Belgian breweries differ considerably from those used in Britain; the lager beers win more and more ground and breweries are characterized by the great number of different types of beer produced.  Every brewery manufactures six or seven different kinds and this diversity is necessary in a country where so much beer is consumed.  The innovations in the Belgian brewery will therefore, perhaps not apply to the British brewery, but the principles may come in useful in many cases.  Here it may be mentioned that some of these new ideas are still at the experimental stage, but the tendency remains always the same: to produce better at a lower cost.

Brewing Materials.—Great consumer of brewing barley as she was, Belgium did not produce any before the war.  She only grew six-rowed barley, the better varieties of which were used for top fermentation beers.  During the war, two-rowed barleys were sown, which gave a better yield and in this way the Kenia variety was introduced into Belgian agriculture. Today the brewer finds part of his two-rowed barleys at home.  This is not an innovation, far from it; Belgium has simply caught up with some other countries in this respect.

Malting.—Maltings have not undergone any alterations in Belgium.  Malting is chiefly done in Saladin boxes.  As the capacity of the existing plants is already too high, no new ones are being built.  Every effort is made to reduce manufacturing losses without spoiling the quality, and it is chiefly in the respiration of the grain and in the malt culms that economies are sought.  The Kropff system has been well known for many years; its principle is to reduce the air supply for the germinating malt at the end of the malting.  The enzymes formed at the start keep on modifying the malt at this stage, but the consumption of carbohydrates and the formation of rootlets are impaired through the lack of air.  To make this technique successful, it is necessary to control the respiration of the grain.  As mentioned above, the enzymes are formed at the beginning of the malting process, when the respiration grows in importance.  When the latter moderates, the enzymes have been formed and aeration can then be reduced.  In the larger maltings respiration is controlled, and thus, without any special machinery, losses are reduced by 1 per cent.

Another method giving an even higher economy has been patented by P. Fröschel (C.R. Congrés Internal. Ind. Ferm., Ghent. 1947, p. 195).  This author, a botanist, has studied the inhibiting substances present in barley.  All species of grains contain soluble principles in their hulls, and these exert an inhibiting or a retarding influence on germination.  These principles pass into the steep water, from which they can be extracted.  On sprinkling the malt on the floors with these substances, respiration is reduced and with it the growth of rootlets.  This procedure diminishes the malting losses by 2 per cent.  It must be said that this method has only been tried out on an industrial scale, but has not gone beyond the experimental stage.

The malt kilns existing in Belgium before the war were sufficient to cover all needs and therefore, no new ones have been built.  All are equipped with fans so as to allow deep layers and reduce the building costs.  Before the war there was a tendency to work in very deep layers (1 metre), with powerful aeration and no turning over so as to complete the process in 24 hr.  A hygrometer suspended above the layer indicates when the malt is dry.  These kilns are much cheaper to build and require much less labour to run them.  Quite good pale malts are produced on such kilns, but it is very difficult to get good dark malts in this way.

Brewing.—Brewing has hardly changed, but more and more attention is paid to liquor treatment. Certain breweries de-mineralize their water by means of ion exchangers.  This constitutes an important factor in the improvement of the quality of the beer and counter-balances the effect of other economies which might have a less favourable effect.

Hopping.—If brewing has not been altered to any extent, the question of the hopping has attracted considerable attention.  Study was made before the war of the practical use of the analysis of hops.  In Great Britain the analytical valuation of hops is generally the determination of antiseptic power, according to the formula a+ß/3.  This antiseptic power is of less significance for Belgian beers and it is the bitter value which is most important. From his experiments on the bittering power of the hop resins, Wöllmer concluded that the bitter value could find its expression in the formula a+ß/g.  Thorough tests, industrially, on the application of this formula have established with certainty that it has a great practical value.  Calculating the hop rate according to its bitter value, much more regularity can be obtained in the bitterness of the beer and many Belgian brewers now calculate their hopping according to the bitter value given by the analysis.  Buying hops, other qualities being equal, they choose those which have the strongest bitter value.  It is obvious that the same bitterness is not produced in all beers with the same bitter value in the hops, because a number of factors may influence the bitterness and amongst these, chiefly the composition of the liquor.  But once the right bitterness is fixed, the bitter value of the different hops is established and when another hop is used it is not exactly the same weight that is taken, but a proportion giving the same bitter value.

Another great novelty took shape in Belgium with reference to the hop extraction.  Govaert (M. Verzele and F. Govaert, ibid., p. 292; cf. this Journ., 1949, 175) and his co-workers made a careful study on the chromatographic separation of the hop resins.  This method made it possible, not only to measure more exactly the hop resins, but also to separate those present in the beer.  From his investigations Govaert concludes that the bitterness of the beer is given by an isomeric transformation product of the humulon, which he calls isohumulon.  The other transformation products of the resins would be without any value. The following are the formulae for humulon and isohumulon:

Isohumulon is much more soluble than humulon itself and is therefore the essential factor in the bitterness of beer. 

When hops are boiled in the copper, only part of the humulon changes into isohumulon, the remainder becoming resins without any value.  Govaert has thus elaborated a procedure, which is patented, and which has for its object the transformation of the humulon into isohumulon in the hop itself before it is added in the copper.  This is done by means of treatment in an alkaline medium.  In this way there are no more losses of humulon and the author claims a saving of 50 per cent, in the hopping.  This method, which is quite new, has already been tried in several Belgian breweries.  The hop saving is certain, but does not reach the 50 per cent, claimed.  The experiments have not yet been taken far enough to know all the effects this procedure may exert on the other qualities of beer.

Cooling.—Here the Belgian breweries have turned their eyes to Britain.  The new refrigerators are all plate-coolers, which British breweries were first to adopt.  In comparison with the Baudelot (vertical) refrigerators they allow a great economy in space and in labour and give a much greater bacteriological security.  Up to now, only a few experiments have been conducted on the clarification of wort by means of centrifugal treatment or by filtration through diatomaceous earth (kieselguhr), such as is done in America.  Centrifugal treatment seems able to replace the settling of the wort on the surface cooler, and avoids considerable spoilage.  However, existing plants will not soon be worn out, and therefore a long time will pass before centrifuges will take their place.  Filtration through kieselguhr has been tried, principally to accelerate the maturing of the beer in the lager cellars.  Further reference to this subject will be made below.

Fermentation.—Unlike British breweries, nearly all Belgian breweries now work with pure yeast cultures, both in top and in bottom fermentation.  This certainly gives more regularity in the brewings and makes possible the choice and maintenance of those yeasts which are most favourable in each brewery.  Evidently, when starting to ferment with pure yeast, the best results are not obtained right away.  Several strains must be tried before finding a good one and it often takes quite a long time.  The composition of the brewing materials may sometimes necessitate the choice of another yeast, because the attenuation goes too far or not far enough.  But when there is available a series of pure yeasts of good quality as regards the flavor of the beer, the attenuation, etc., it is always possible to propagate the one which suits best, and this is a great asset.  The strain of yeast does not mean everything; the acclimatization also plays a definite part.  In this respect some astonishing happenings were witnessed during the war.

In the first period of the war, Belgian breweries received important quotas of sugar as brewing material.  Certain breweries, which were running out of malt, added more and more sugar, fearing all the time that the fermentations would get weaker; but nothing abnormal happened.  At one brewery the amount of sugar reached nearly 70 per cent, of the materials, for a wort of 5*4 per cent. extract (sp. gr. 1021), and the yeast kept on fermenting nearly normally.  It may be mentioned that it was a pure ale yeast, isolated from an English yeast.  Suddenly the sugar allocations stopped and it was necessary to come back to malt alone.  Right away, the yeast did not rise to the surface anymore and remained in suspension in the beer, the attenuation remaining normal.  It took some time before it again became acclimatized to the malt and behaved normally.

Another acclimatization phenomenon: The gravity of the beer was strictly limited to 4*7 per cent, extract maximum, but with the idea that yeast could not maintain its vitality in such weak worts the brewers were allowed to ferment heavier worts, the beer having to be diluted afterwards.  For lager beer, it was generally necessary to adopt this procedure, but for the top fermentation it was realized that the fermentations were satisfactory not withstanding the weak wort, and it was sufficient to regenerate the yeast from time to time in a stronger brew.  After a certain period it was noticed, however, that this regeneration did more harm than good to the fermentation and that it was preferable to let the yeast get acclimatized to the low gravity.  In this respect a certain yeast may be mentioned, that since the war has been fermenting exclusively worts of a gravity never superior to 2-6 per cent. (sp. gr. 1010) extract without renewal, and the fermentation is still perfect.  It seems therefore preferable for a yeast to ferment always worts of the same gravity.

A third acclimatization phenomenon has been noticed during the war, but here it concerns bacteria.  At first, when the gravity of the beers dropped suddenly, rods and sarcina were no longer found, and the phenomenon got such that it was necessary to fetch old cultures of these organisms to show to students.  When the war had lasted two years, these micro-organisms appeared again and progressively their number grew till the end of the war.  As soon as the beers were brought back to their normal strength, they immediately became more virulent.

Storage (Lagering).—The war beers, being very weak, were much more sensitive to oxidation because of their deficiency in reductones.  The flavour of these beers was easily affected by oxidation.  For this reason, the brewers soon learned, especially during that period, how to preserve their beer from the influence of the air and to minimize oxidation.  Reductones were manufactured with sugar and added to the beer.  By so doing it was possible to avoid the astringent taste, which results from the oxidation of the tannin.  When a sufficient amount of reductones is added to beer, the oxygen is fixed before it can oxidize the tannin, and the flavour of the beer remains purer.

Certain Belgian brewers find themselves under the necessity of shortening the storage of their beer; some because they keep on growing in importance notwithstanding the general crisis, others because in the pre-war days they had specialized in conditioned top fermentation beers, which required a short period of storage only, whilst now they are asked to brew lager beer which normally has to be stored for a longer period.  That is why studies are now being made of certain methods to shorten the lagering.  Some of these are based on a slight oxidation of the beer after fermentation, with the object of destroying the “young” flavours and of precipitating the turbidity.  This oxidation is followed by a carbonic acid saturation.  Filtration of the wort through kieselguhr is another means to hasten ripening, adopted in the United States.  This method certainly accelerates the maturation. One objection to this procedure is that it makes the beer thin, but experiments show that the beer becomes bright and tastes mature sooner, and does not become thin unless it is left for too long a period in the lager tank.  In any case, there is always the choice of filtering only part of the wort through kieselguhr.

Up to now, this procedure has not been sufficiently studied in Belgium and it is not certain yet that it will give beers as good as those matured normally.  It is possible that the beers with a short maturation period require another yeast or a different kind of fermentation.

Filtration.—Since the war, beer filtration has been the object of many experiments.  The pulp filter, which was generally used, demands too much labour, produces too much beer loss and is a cause of numerous infections.  To take its place, there is choice of the plate-filter, the kieselguhr filter, and the centrifugal separator.  All three offer the advantage of requiring less labour and producing less spoilage.  However, the plate-filter gets easily clogged up, the kieselguhr filter lets yeast through, and the centrifuge gives less brilliant beer.  Individual choice must be made in every special case.  The kieselguhr filter is perfect for very turbid beers, but has to be followed by a plate-filter to avoid yeast-turbidity.  The plate-filter is too quickly clogged when the beer is not sufficiently settled down.  The centrifuge followed by a plate-filter is the easiest to handle and gives the least spoilage. This apparatus also offers the advantage that very clear beers or dark beers can be clarified satisfactorily by means of only a separator; but the output of a centrifuge is rather small. Generally, the choice today would be a kieselguhr-filter with a plate-filter for large outputs, and a centrifuge followed by a plate-filter for small outputs.

Racking.—As was said at the start of this paper, bottled beer is on the increase in Belgium. The bottling machinery does not differ from that in use in other countries.  A start has been made in installing pasteurizers.  Previously, beer was sold quickly, but now the turnover is slower; at the same time the customer has become more particular and it is necessary to aim at a longer stability.  The pasteurizers have only been ordered and it is not yet known how the public will accept pasteurized beers.  Anyway, the breweries are studying carefully the means to preserve their beers from the flavours and turbidities that may accompany pasteurization, and this before they adopt this innovation in practice.

Barrels also constitute an important problem. The lack of oak wood and the high cost of wooden barrels were the cause of many experiments with metallic kegs.  Trial has been made of coated steel, aluminium alloys, and stainless steel, but the perfect metallic barrel has not yet been discovered.

A novelty in the way of barrels has been patented in Belgium during the war.  It is a barrel with a pouch, but its use has not left the experimental stage so far.  As the drawing shows, it is a barrel in which one of the ends has been replaced by a metallic plate (3) in which is inserted, around a big oval flange, easily removable, a rubber pouch (4) of the same capacity as the barrel.  In the centre of this metallic piece is located the filling bung (1), which is opened by lowering the valve (2).  To fill the barrel the pouch is first flattened against the plate, blowing air under pressure in between the sides of the barrel and the pouch. The beer pipe is then fixed to the bung and, letting the pressure escape from the barrel, the beer runs into the pouch without loss of carbonic acid, without foam, and without coming in contact with any air.  In order to empty the barrel, a beer faucet is attached and the pressure is again admitted around the pouch.  The wood of the barrel is made impervious by means of a rubber coating so as not to lose any pressure.  It would also be possible to draw the beer off by using water pressure around the pouch.

The advantages of this system are numerous.  There is no need to use an isobarometric filler; no pitching of the barrels is required; the staves can be made of beech instead of oak; the beer is easily cooled by putting ice on the metallic face; the beer does not lose its gas, when the barrel is not hermetically sealed; it does not get infected through the organisms which thrive in between the pieces of wood and which it is impossible to eliminate; the beer does not get spoiled even if it takes several weeks to empty the barrel.  The great difficulty in this apparatus has been to find a kind of rubber perfectly neutral to the taste; it now seems that this difficulty has been overcome.

This barrel is still in the experimental stage; it would appear that the results are such as to indicate that this barrel would be capable of stemming the very expensive sale of bottled beer.

These, then, are some of the different technical problems which the Belgian brewery has to solve.  They are at the origin of numerous theoretical problems still to be studied.  The heads of the Belgian brewing industry have understood the unavoidable necessity of scientific and technical research to keep their industry in pace with progress.  With this object, they have just established an important research centre, subsidized by the whole of the brewing and malting industries, thus following the example of the Institute of Brewing.

Université de Louvain, Belgium.

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