MEETING OF THE NORTH OF ENGLAND SECTION HELD AT MANCHESTER, ON FRIDAY, NOVEMBER 10th, 1916.
The following paper was read and discussed:—
Low Alcoholic Beers.
By O. Overbeck, F.C.S., F.G.S.
Beers in this country may be brewed at any original gravity, the duty to be adjusted on a standard of 1055°. If brewed on unlicensed premises the original gravity must not exceed 1016°, the products being then descriptively termed “table water.” They pay a duty at the rate of 4d. per gallon or 12s. per barrel, and are required to contain not more than 0·98 per cent, of alcohol by weight or 1·14 per cent, by volume, ie. about 2 per cent, of proof spirit. In Denmark the temperance or so-called duty-free beers must not contain more than 2·4 per cent, of alcohol by weight or 4·87 per cent, of proof spirit, which is practically double the limit imposed in this country. In consequence they are better temperance drinks than ours can ever be, and their original gravity ranges from 1027° to 1030°.
It is useful to remember that 9° of attenuation correspond approximately to a production of 2 per cent, of proof spirit, and that an attenuation of 1° would produce in a closed vessel a pressure of 7 lb. per square inch of carbonic acid gas. Consequently, a beer of original gravity 1016° can produce a pressure of 56 lb. at half gravity.
The term “low alcoholic beers” may, I think, be held to include those containing less than 3 per cent, of alcohol (6·74 per cent, of proof spirit). Whether the limit of original gravity may or may not be stated depends entirely upon the process, i.e. whether the fermentation has been naturally or artificially limited, or even stopped by some subsequent process, or, lastly, the alcohol subsequently removed by some method. Excluding for a moment the last, the final percentage of alcohol will depend upon the number of degrees of gravity fermented away, the few last remaining degrees depending more or less on the constitution of the wort itself as well as the extent of the fermentation. After a comparatively short space of time the chemical reactions taking place in the wort of a malt mash arrive at a balancing point, after which the relative constitution of the wort appears to be but little altered: consequently we are led not to magnify unduly the chemical effect of any complicated processes of malt treatment utilised, but rather to favour simplicity, the choice of materials being a far more important question to the attainment of a satisfactory result, with its necessary concomitants. We brew with water, malt (plus or minus substitutes), and hops.
Brewing waters vary immensely, from such extremes as a soft Carboniferous Grit water with, perhaps, only 5 grains of solids per gallon, to a strongly salt Norwich water and the permanently hard gypsum water of Midland districts.
Brewers who possess a nearly pure water, provided it contains nothing really deleterious to brewing, can make it, at a certain expense, what they like. In the opinion of some brewers, however, a natural water containing similar bases, acids, and total solids acts somewhat differently from its artificial substitute. We know little of the manner in which the solids exist as salts in the water. In the calcareous waters of Grimsby we find that 12 grains of chloride of calcium per gallon favours brilliancy and checks rapidity of fermentation.
Our next material, the grist, lends itself to variation both in constitution and proportion. This must be left in any individual case to the discretion of the brewer who possesses knowledge and experience. It will depend much upon what he has already found to suit his own particular case best, and also what his yeast is accustomed to, since materials, systems, and yeasts vary so much in different localities. There are, however, broad lines from which it is unwise to deviate too far. In very weak “beers,” such as the “table waters,” original gravity 1016° maximum, the main difficulty is to keep them fresh to the finish of the barrel. They must, therefore, be used quickly, before the remaining fermentable degrees have vanished. Otherwise they will drink below their gravity, not to mention the fact that the limit of alcohol allowed by law will be exceeded. I would point out the great value we have found in a generous admixture of foreign malt in the grist—we use no substitutes. Foreign malt (long varieties) possesses a steadying effect on yeast, simultaneously with offering a strongly anti-wild-yeast character to the wort, besides giving to the beer the most important advantage of a firm, close, permanent head, generally only associated by the public with beers of a far heavier gravity. This latter property is exhibited strongly in the resultant beer, as compared with such in which foreign malt has not been employed.
There exists naturally a minimum quantity of hops which can produce the necessary bitterness to a given volume of water equal to one brew. This amount must constitute the least possible quantity we can use, and is quite independent of the weak original gravity of the wort. The same applies to the colouring used.
These beers are very sensitive to odours and flavours, and hence the use of a considerable amount of old hops must always be avoided. Again, all worts boiled with a free escape of steam lose their hop aroma during their long boil. We require urgently to retain these, hence the very great advantage which is derived from adding one quarter of the total amount of hops used in the copper only a quarter of an hour before turning out. The improvement in “fresh hop” aroma and real hop flavour (not merely bitterness) in the finished article is most marked, whilst also masking most effectually the low original gravity of the beers.
In carrying out the fermentation of such worts, too much stress cannot be laid on the value of clean surroundings, especially owing to the long time the wort remains exposed to the attacks of germs before it covers itself with the slightest protective head. It is preferable to employ a system of air filtration. So much has this been found to be true that all fermenting vessels in Grimsby containing such weak worts are covered in completely with cotton twill sheets, freshly washed, steeped in a very weak solution of sulphurous acid, and subsequently wrung out. These sheets are only removed after taking off the first dirty head or during the one skimming. They are then at once replaced. Although apparently still quite clean after each brew, they are really, of course, heavily germ laden.
We must bear in mind that, after fermentation has commenced, the rising carbonic acid gas from the fermenting wort acts as a protection against incoming air.
In the case of the Yorkshire stone square system, if the brew could be made to work out so exactly as to leave the back drink vessel dry, it would be so much the better, but this is not possible without a manhole deep enough to hold the head and its “froth-wort.” In such a case the top stone would act itself as a protection from germs, and, by keeping the valve there closed, with the addition of a small cover over the manhole, below the edge of which the yeast would only rise, such an arrangement would fulfil the requirements of the case. If not, as is usual in practice, it is better that the top vessel wort should be fairly deep, thus rendering the top shallow wort layer deeper than usual, in order to minimise the deterioration of this top drink from its having been over-yeasted at top and bottom, since we do not circulate or pump at all, and back drink vessels would hardly cover themselves properly after being skimmed clean. Moreover, the final beer would be unduly flat.
We find that a brew of original gravity 1015—1020°, pitched on Monday evening, will be ready to rack at half gravity on Thursday morning. From this period it steadily and naturally deteriorates in body in the fermenting vessels, until, after a week, it is nearly spoilt, as far as character is concerned. On the Saturday it may be racked at a gravity of 1008°, but only with the most rigorous attention to the brew, and by constantly guarding against any rise in temperature.
Pitched on Monday at 1015—1020°, with 3 to 4 oz. of yeast per barrel, say at 5 P.M., at 59° F., the wort will only have covered itself properly with a head by Tuesday evening, when it will have risen in temperature to 60° F., and have lost only 1° of gravity.
The water jackets (shells), where these are used, must be filled beforehand with water, to prevent any rapid cooling by accidental draught, or to guard against an undue rapid rise. By Wednesday morning the gravity will have sunk to 1016°, and the temperature should be between 60·5° F. and 61° F. At this stage we lower it gradually to 60° F. and keep it there.
In this way we can lengthen the process somewhat to fit in other rackings if necessary, but, above all, we minimise all risk of any undue multiplication of germs by limiting that rise of temperature favourable to them, let the food be what it may.
Upon the day of racking the manhole and back, or tun surface, as the case may be, is cleared absolutely of all trace of yeast-head (for by this time this has settled down to a close brown cap), the vessel covered again with its sheet, and the whole racked at a temperature of 60° F.—if working in summer, down to 57° F.
Each barrel, besides the usual cleansing, is allowed to stand all night, corked and loosely shived with the addition of a wineglassful of sulphurous acid solution of specific gravity about 1025°, so that before filling the open pores of the wood may be sterilised. One third the usual amount of finings having been added to each barrel previous to the period of racking, these are at once filled, shived tight, and rolled well, and in two hours are star bright, and ready to go out, possessing already thus considerable condition, as is abundantly exemplified by the froth of racking—due in its tenacity largely to the thin foreign malt used. For preservative we employ half the amount we used for our good old-fashioned beer of original gravity 1055°. From those who have never brewed this kind of beer, we often hear doubts expressed as to its keeping powers. With us, as brewed above, at an original gravity of 1016° during the months of July and August—the two hottest months of the year—we find that the barrels set aside for experimental purposes are still as good as ever, i.e., after four months’ storage.
When brewed at table water gravity (1016°) as above, and racked at 1008°, the beer is within the temperance limit of 1 per cent, alcohol or 2 per cent, proof spirit roughly, but in time it will exceed this limit.
To be and remain a temperance drink attenuation gravity of the beer must not exceed 1010°; but it is doubtful whether any sale could be effected, except during times of the year when low or moderate temperatures obtain. In any case the storage would have to be of short duration.
We must also not lose sight of the fact that that variety of acidity in beer which increases generally most rapidly is that due to the oxidation of the alcohol present into acetic acid through ferment action. Now these beers do not possess enough original alcohol to be even able to become very sour by these means alone. Again the percentage of other acidifying matters (decomposed albuminoids, &c.) is also, in a like proportion, low. The same may be said with regard to inherent liability to cloudiness. Given the best aseptic conditions of production and storage in barrel, not much need be feared on this score. The truth is the beers are too weak to be able to become seriously sick at all. Little endeavour seems to have been made towards the production of a really good strong beer, of low alcoholic content, fully fermented and therefore possessing the completed and perfected beer character, and so as usual we must still look abroad for such a product, turning our attention especially towards our Allies the Belgians. In Belgium especially many curious drinks of a beer nature command a good sale. In order to be the better able to appreciate the wider expansion of this question here, I will refer to a few of these, which may be new to some of you and prove interesting, for the Belgians have been working practically now in this direction, upon a commercial scale, for a long time.
Liège Saison Beer.
This Belgian product had an original gravity of 1020—1025°, the proportion of hops being very high, viz., 7 to 10 lb. per quarter, and at least half of these were Bavarians or Alsatians. This beer was attenuated to half gravity. Being a spirit-drinking district this harsh drink only just held its own. (The top-fermentation drinks of Cologne and Dresden ore similar, those of the former city varying near an original gravity of 1040°.)
The workmen preferred these top to bottom yeast beers as having more flavour, yet being less intoxicating.
In Liege the beers were wastefully fermented in casks to preserve aroma, the dirty overflow being caught in tubs. They were sometimes also cleansed into barrels, or dropped and skimmed and then racked from settling tanks. In consequence such beers proved comparatively tasteless, and did not, moreover, recover themselves in barrel. This cask fermentation was always carried out by means of a special yeast, which was obtainable in the North of France, Belgium, and Holland. Such yeasts, attenuating to half gravity, could be obtained from Dutch villages, and in frontier towns, especially in Maestricht. This yeast comprised two types, one rapid and fermenting only free maltose and low malto-dextrins. The fermentation was complete in from 24 to 48 hours after pitching and required a temperature from 62° to 65° F. The gravity would have fallen about 45—48 per cent, of the original. The beer was fined out after 24 hours, the finings working out through the bungholes, and skate skins being generally used for finings.
Having being topped with bright beer, the barrels were then poroused, when the activity of the second type of yeast commenced, plenty of this latter adhering to the sides of the barrels. In six to eight days it was in full condition and ready for consumption. Such beers carried a good yellowish head, the colour being probably due to hop resins. Drinkers who once became acclimatised to such harsh beer preferred it to all others. It bottled well and was fairly stable, but its deposit was naturally very thick.
Belgian brewers long ago found out what we are now experiencing, viz., that a beer of original gravity 1015° to 1025° keeps better than one between 1030° and 1040°, on account of its being a comparatively inferior pabulum for bacteria.
Ten to 15 per cent, of spelt was also sometimes used with the grist, and it was valuable both for mash-tun drainage, and also for contributing body to the beer. The alcoholic content of these beers varied from 1 to 2 per cent, by weight.
Louvain White Beer.
This beer had an original gravity between 1025° and 1030°. Part unboiled wort was sometimes added from the mash-tun to that from the coppers on the cooler, thus introducing lactic, butyric, and other ferments, and also, notably, at times, “packet” sarcina of various species. All those latter contributed specific flavours. The bulk of the malt used was air dried, and 65—75 per cent, was employed, with the addition of 25—35 per cent, of raw or malted oats.
In this beer raw wheat replaced the oats. Louvain beers were generally only very lightly hopped, and generally only with old hops—yearlings and older.
This beer was fermented in the barrel, with the addition of a special “white beer yeast,” bunged and stood on end, a wooden funnel 10 inches in diameter being placed over the bunghole to prevent loss on to the floor—a dirty process. This funnel retained the yeast and acted like a top vessel, more or less as in the stone square system. The beer possessed a milky, yellowish colour, like our ginger beer. Microscopically speaking, it was very impure. It smelt strongly of butyric ether (ethyl butyrate), i.e., like pineapples. So strong was this fermentation that the hydrogen gas would even sometimes flash with a bluelight if a match were brought into contact with the gas escaping from it. (The Berlin “Weissbier” is somewhat analogous, being, however, of a somewhat higher gravity, and brewed from raw wheat and air-dried malt. The See Strasse Brewing School distributed the variety of pitching yeast-mixture, or the brewers interchanges theirs. It smells more strongly of pineapple than Louvain, to obtain the advantage of the aroma of which it is drunk from wide deep glasses, which buries the nose in the aroma. It possesses the well known “close” wheat head, is eub-acid, and most refreshing, but mawkish if too sweet, with little hop aroma, and often served with a floating slice of lemon. Its turbidity consists of precipitates (raw grain albuminoids) and ferments. When bright it tastes thin, and is condemned for its brilliancy. Unfortunately we never suffer from this complaint from our publicans! Therefore, to retain the milkiness, some brewers add starchy wort; but if they then even do not possess the “right style” of turbidity, they are similarly condemned for it. These glutinous substances add viscosity, retain the carbonic acid, giving “sting,” and, moreover, hide weakness.)
Much stress is laid upon the aroma of weak beers, but when we appreciate the fact that this is mostly a secondary production except the furfural and hop aroma, all theories of pressure fermentations in a thousand different forms fall to the ground more or less. This is well shown up in bottled beers, and the proof of absence of aroma in all pure wort cultures assists it.
Even fermentations in closed syphons do not produce this aroma where there is no loss or escape of gas due to frothing, which we appreciate in our tun rooms to the full. A wort of original gravity 1030° will produce a gas pressure of 135 lb. per square inch, and most syphons can stand this.
A 1016° original gravity beer would produce at half gravity, a pressure of some 70 lb. per square inch.
Many patent pressure processes exist, but do not seem to make much headway. Fermentation proceeds farther in varnished or pitched vessels or in metallic ones, i.e., on polished surfaces—generally ascribed to increased motion of the yeast to new “unexhausted” surroundings, in comparison with the fixity of a nidus with stationary wort around it.
“S. Thermantitonum Beer”
Thermantitonum yeast, as its name implies, ferments at a high temperature; and fermentation ceases at 60° F. A very dextrinous wort is necessary. This yeast settles densely and quickly, thus assisting clarification; the gas pressure may be preserved to a certain extent in the beer. Such beers drink, however, very thin.
The Danish yeasts which rise or sink, according if high or low, at a 1—2 per cent, of alcohol content in the beer are very valuable, since they can then be cleansed on the surface or decanted. One Danish yeast should be of great value to us in England, since it is said not to be able to produce more than 1 per cent, of alcohol under any circumstances!
Of course, we can always check fermentation by fall of temperature. This, however, must be gradual, or we may have to reckon with “yeast bite.” In some cases even double filtration is resorted to, firstly rough, secondly fine.
Restriction of Diastatic Action.
Processes for the limitation of diastatic action are legion. “What we have to avoid in these are set mashes, sticky goods, and cloudy worts, and especially soluble starch, not to speak of any loss of extract at the present price of malt. Just as soluble diastase has been used to counteract this drawback, so have also papain and pepsin been employed to clarify beer in barrel or bottle, clouded from insoluble albuminoids. The best preparations convert 6,000 times their weight of albuminoids. This is especially of value in raw grain worts.
Pasteurisation, or the crippling of ferments in the bottle, is generally carried out at 135—140° F. the lower the better. This is not, however, universally true. The increased pasteurisation deposits thus produced at the higher temperatures are the reason for this. If the heat be too high the flavour may also be affected or even ruined.
Later improvements mark great advances, however, on this process, the great secret being that the maximum temperature permitted should also be the highest temperature available. Beers treated by these processes appear to be, however, somewhat sensitive to light. In Denmark all bottled beer is pasteurised.
Long cold storage, of course, acts beneficially so far as clarification is concerned, but is too costly. In America these difficulties appeal to them far more strongly than they do to us. Many Danes, like the Belgians, are dram drinkers; here again, to such the stronger beers appeal most strongly. Stopped at “temperance stage” these, however, often taste “worty.” To assist clarification again, agar-agar is, after having been soaked, thrown into the copper some few minutes before turning out. It, however, spoils the pitching yeast and deteriorates the sludge character for draining-off purposes.
Beers of original gravity 1020°, arrested at 1010°, primed, chilled, filtered, and pasteurised, “sound” all right. They, however, lack all character.
A beer of original gravity 1016° fermented with special yeast, bottled and matured slowly, gives an aromatic good beer, but unfortunately also much sediment. It can easily be made to remain at 1007° and be a real temperance’ beer, in contradistinction to the Liquor Control’s beer. If brewed at 1014° the 2° can be made up by priming. If this be added to the “up” beer, it has been proposed to cool it and saturate it with CO2 first to prevent subsequent flatness due to absorption of the gas.
A composite process employs two tuns and two pressure vessels. In one is a hopped wort of specific gravity 1016°, in the other a hopped pure cane-sugar solution of specific gravity 1040°. This latter, after having been skimmed above 1031°, is run into one pressure vessel (filled), where it develops an aroma during its secondary fermentation. It is blended finally, chilled, filtered, and bottled.
An interesting discussion followed the reading of Mr. Overbeck’s paper, but an account of this cannot be published as, unfortunately, the notes were lost in the post.