By J. A. Burns, A.R.I.C.

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May-June, 1944] 119 II. THE FINING OF BEER By J. A. Burns, A.R.I.C. The use of finings to assist clarification has become an essential process in the brewing of English top-fermentation beers.

1 May-June, 1944] 119 II. THE FINING OF BEER By J. A. Burns, A.R.I.C. The use of finings to assist clarification has become an essential process in the brewing of English top-fermentation beers. We may look back regretfully to a golden age of brewing when beers of a generous gravity were vatted up to undergo secondary fermen tation and then drop bright without any adventitious aid. But as our beer is brewed and consumed to-day, artificial means of clarification must be employed and isinglass finings fulfil all the requirements'in a quite remarkable manner. Beer is a fluid of very mild acidity, and one, moreover, in which a change of half a unit on the pn scale would be almost inadmissable. Dispersed in the beer are colloids and soluble bodies of high molecular weight on which its character and taste are largely dependent. As racked from the fermenting vessel it holds in suspension yeast cells and particles of prctein-resin-tannin-mineral matter of variable composition. The requirement is to cause this suspended matter to coagulate without altering the pu, and without remov ing or adding substances which would affect the taste. It is doubtless true that the suspended matter in beer carries electric charges which are relatively small compared with the mass of the particles, but the colloids present carry much greater charges relative to their mass. If, therefore, an oppositely charged colloid be added it is more likely to precipitate the beer colloids than to neutralize the relatively weak charges on the suspended matter. Beyond this very general statement it is difficult to discuss the physical chemistry of the fining process. No scientific work has been done on the colloidal and micro-particle systems of beer and arguments by analogy with other colloidal systems are more likely to be misleading than helpful. The paper on finings by H. W. Harman, J. H. Oliver and P. Woodhouse (this Journ., 1928, 203) and that by R. H. Hopkins (ibid., 1931, 423) remain the outstanding publications on the subject. The elegance of the isinglass fining process is apparent when it is contrasted with other clarifying reactions. First there is the cookery method, adopted by the bacteriol ogist, of coagulating white of egg in the fluid to be clarified. While this may have some effect on the colloidal systems present, it does not alter the pa and does not precipitate soluble complex molecules such as protein and carbohydrate degradation products. The reaction, however, can only be secured by heating the fluid to a temperature well above the coagulating heat of albumen and on this ground alone is inadmissible in the case of beer. Then there are various applications of the clarifying power of aluminium hydroxide. Alumina cream is a useful and very effective laboratory reagent, and, as the reaction product of sodium aluminate, is now applied extensively on a large scale to water puri fication. However, alumina adsorbs colloids and even dissolved substances of high molecular weight and so drastically alters the taste of beer that its use must be ruled out. Tannic acid and tannins combine with many complex molecules to form insoluble substances. The reaction is generally re garded as a chemical one rather than as a physical adsorption, although the products may vary in composition according to the proportions of the reactants. In wort and beer the reaction is with complex nitrogenous and caramel substances which combine with small amounts of tannic add to produce a haze and with larger additions a flocculent precipitate. The latter reaction is of little value for practical clarification of beer as the flavour is radically altered and it is usually noticable that although there is an abundant flocculent precipitate with removal of all coarse particles yet the beer still holds in suspension an unfiltrable grey haze. The reaction with small amounts of tannic acid, of the order of 100 parts per million or 2 pints per barrel of a 1 per cent, solution, has, however, been applied in practice to precipi tate substances on the verge of solubility, so that subsequent fining will produce a brilliant beer proof against pasteurization, usually with appreciable reduction of colour. Certain Bentonite clays possess valuable flocculating and adsorbent properties which have been applied to the clarification of beer and wine. Rates proposed for wine by N. M. J. Brelaz (Brewer and Wine Merchant, Feb., 1937, p. 72) varied from 2\ to 15 Ib. per

120 burns: the fining of beer [May-June, 1944 1,000 gallons of wine, which corresponds to 14 to 86 oz. per barrel, which would be an excessive rate for beer.

2 120 burns: the fining of beer [May-June, ,000 gallons of wine, which corresponds to 14 to 86 oz. per barrel, which would be an excessive rate for beer. For a certain prepar ation used on the Continent rates of 1 to 5 oz. per barrel were recommended for beer. These Bentonites might repay further investi gation as adsorbents in the haze-proofing of pasteurized beer, or as possible substitutes in the event of isinglass being unprocurable. Solutions of sodium silicate, or rather colloidal silica, have been adapted for fining beer. They produce a good flocculation and, in some cases, bright beer, but generally their action is less effdctive than that of isinglass. Here again further study might yield an improved material if there was a demand for it. Solutions of Irish moss have long been used as copper finings and as a finings auxiliary to assist the action of isinglass. More recently, alginic acid, also extracted from seaweed, has been used as a finings auxiliary and even suggested as a fining agent. The molecular aggregation of alginic acid can be varied within wide limits so that it will precipitate in any form from a sandy floe to a gel. A suitable form of this acid when added to beer as the sodium salt will produce a flocculent precipitate which carries down suspended particles. Three to 6 pints per barrel of 1 per cent, solution of alginic acid must be added to produce a sufficiently abundant precipitate which is about double the weight of isinglass in the commonly used rates of findings, that is to say 2 to 3 pints per barrel of a 0-3 to 0*6 per cent, solution. The action of alginic add is not so effective as that of isinglass; it will clarify some beers to brilliant condition, but in other cases a fine haze remains in suspension. Alginic acid, if used as a finings auxiliary in conjunction with isinglass at the rate of about 2 pints per barrel of a 0*1 per cent. solution, will hasten fining and may be of practical use in the same way as Irish moss solution. None of these reagents clarifies beer so effectively and with so little alteration to flavour as does isinglass finings. When used as auxiliaries such reagents may be employed to remedy defects in a beer, but are of little value unless followed by good isinglass finings. Various proprietary brands of "Auxiliary Finings" are offered to brewers. They con sist for the most part of solutions of Irish moss and are doubtless of value in some cases, but are not a general remedy for all fining difficulties. Harman, Oliver and Woodhouse (loc. tit.) pointed out that the colloids of Irish moss and isinglass possess different electrical charges and induce mutual pre cipitation so that by. producing a more abundant flocculation their addition may assist the fining of beers which have been racked too clean and they may in some cases remove wild yeast if not present in excessive amount. Some North Country brewers re port that slow fermentation types of beers commonly show some beneficial effect from the use of Irish moss solution, but in the case of fast and attenuative types of yeast the addition of auxiliaries of this nature may lead to the production of haze after fining. Irish moss, alginic acid, tannic acid, malt extract, sugar priming and yeast (either as pitching yeast or as krausening) have been proposed as remedies for defective fining, but whether any one of these would be of use. in a particular case can only be decided by trial. Clarification and fining may also be assisted by the use of " Copper Finings." Irish moss, alginic acid and kieselguhr are substances commonly employed. Excess of Irish moss may affect yeast head formation and fer mentation. The resultant beer may rack too clean while reacting so rapidly with isinglass as to produce fining in layers. Kieselguhr acts by adsorbing colloids and by weighting the flocculent precipitate in the copper so that it settles more rapidly in the hop back. Here again, indiscriminate use is liable adversely to affect yeast behaviour during fermentation. Some brewers believe that wort clarification is influenced by skimming dirty heads from the fermenting. vessels. It is said that Yorkshire Stone Square types of yeast will benefit by the removal of dirty heads. In the case of fast attenuative yeasts, which are liable to remain in suspension in the beer, the presence of additional coarse amorphous matter assists clarification in the fermenting vessel and helps to secure an adjustment of the amount of yeast and amorphous matter in suspension at racking. Copper finings and mechanical aids to wort clarification are sometimes helpful, sometimes just the reverse, and the brewer must decide on their value according to conditions prevailing at the time in his brewery since

May-June, 1944] burns: the fining of beer 121 the need for auxiliaries may change from time to time according to the reaction of the yeast to the brewing materials available.

3 May-June, 1944] burns: the fining of beer 121 the need for auxiliaries may change from time to time according to the reaction of the yeast to the brewing materials available. Isinglass consists of the swimming bladders of certain fish and is generally named from the country of its origin. In normal times the various qualities differ greatly in price, the more highly priced being paler in colour and generally of more pleasing appearance and less noticeable smell. These differences disappear in the course of preparing the finings and it is doubtful if price is a reliable index to fining capacity. On the other hand, in a single consignment of isinglass the brewer may have to grade the sounds so that in each batch of finings modification takes place evenly. This is unnecessary where mechan ical aids to disintegration are employed, but may result in more economical utilization of the isinglass in the slow process of making finings. On the same argument, when it is desired to use more than one kind of isinglass some brewers prefer to cut each grade separately and blend the finished finings so that full use may be made of the harder sounds without danger of overmodifying the softer varieties. J. S. Ford, in his Horace Brown Mem orial Lecture (ibid., 1941, 342), reviewed experiments on 26 different grades of isinglass ranging in price from Is. 5d. to 10s. 6d. per Ib. (in 1933). He describes the estimation of collagen by a colloidal gold method which showed that the various qualities did not differ by more than 10 per cent, in collagen content. The samples were made up into finings and used at 2, 1,, \, and \ pint per barrel to fine beers of one brewery. Only at the lowest rate was there any difference between the samples from which it was concluded that under the working conditions of that brewery, provided the isinglass was free from smell, any of the varieties tested was suitable for fining beer. All beers may not be as indifferent to variety of isinglass as those tested by J. S. Ford. Harman, Oliver and Woodhouse (loc. cit.) found that isinglass from Saigon, India or Russia was suitable for beers brewed with more alkaline waters, while Brazilian isin glass was only effective if the water had been acidified or thoroughly boiled. Penang had the widest pa range and was suitable for beer brewed with soft water. Long Saigon is reputed to be capable of re-fining more frequently than any other isinglass by which is meant that after a cask has fined down and is subsequently moved the finings will again settle leaving brilliant beer. It is claimed that this can be done more satis factorily with Long Saigon finings than with any other kind. Some varieties modify more quickly and evenly than others and these differences should be kept in mind when making finings by the slow process. It is generally recognized that when made under identical conditions the different varieties of isinglass give finings of widely varying viscosity. Harman, Oliver and Woodhouse (loc. cit.) give a list of viscosities varying from 1-2 units for Russian to 186 units for Brazilian. Dilution of all these to the same viscosity would give finings which might vary greatly in their effectiveness and conversely finings of different viscosity might be equally effective on a given beer. The viscosity of finings is not, however, without some practical significance. Thin finings tend to give a sandy break which settles compactly to the bottom of a cask. Viscous finings give larger floes, which are more liable to float up either before or at the moment of drawing the beer a condition which is accentuated if the beer has a very low yeast content. On the other hand, when the coagulum is required to purge itself out of the bung hole as in the London practice of "Fining Out" beers, it is desirable that finings should break in large light clots and accordingly more viscous findings give a better cleansing' of the beer. Concerning the preparation of finings, the rapid process described by A. C. Reavenall (ibid, 1936, 373) has been used with complete success and with many different varieties of isinglass. The coarser grades have been found to disperse as easily as the superior qualities available before the war. Since that paper was published experiments have been made on various ways of disintegrating the isinglass sounds prior to cutting with acid. Shredding too finely caused the shreads to swell so rapidly that a compact intractable mass formed during the cutting which could not be dispersed by the gentle stirring applied during dilution. Strips about l/10th in. thick, or even slightly larger, are excellent and can be cut from the sounds as received in the type of machine used for chopping tobacco. If this process is compared with one

4 122 BURKS: THE FINING OF BEER [May-June, 1944 patented by A. H. Gillman and Gillman & Spencer, Ltd. (Eng. Pat. 521,142, 14th May, 1940, this Journ., 1940, 384), in which the isinglass is shredded in a beater mill to fluffy, fibrous condition, it is observed that the Gillman process calls for stirring at high speed throughout cutting and dilution so that the isinglass is never allowed to settle to a dense mass. The claim is made that finings can be prepared in one hour. Com parison of these two rapid processes with the slow process working on whole sounds would indicate that the duration of the cut and dilution is conditioned only by the degree of mechanical disintegration employed to assist the penetration of the acids. The use of a rapid process permits a heavy reduction in the quantity of finings in process of manufacture, which in turn represents a considerable economy of space and capital outlay and, in the summer, of refrigeration as finings deteriorate rapidly if their temperature is allowed to rise over 70 F. Old beer was formerly used for cutting isinglass, but for many years now the use of tartaric and sulphurous acids has been almost universal. It may be of interest, however, to consider the use of other acids. R. Johnson and G. E. Dodds (/. Inc. Brew. Guild, 1939, 25, 56-64; this Journ., 1939, 271) state that finings made with sulphurous acid alone require more time to prepare, but remain in good condition much longer than those made with the usual mixture. Finings made with sulphurous acid alone are less rapid in action. A patent by the Enzymic Malt Co., Ltd. (Eng. Pat. 531,529, 6th Jan., 1941; this Journ., 1941, 158), proposes the use of a cutting acid produced by souring sweet wort with lactic bacteria to an acid content of 1 per cent., followed by sterilization and concentration to half volume. When the shortage of tartaric acid became acute experiments were made with sul phurous acid alone and with citric and lactic acid together with the usual sulphurous acid. Sulphurous acid alone gives very thin finings with a rather poor fining power; lactic acid and citric acid gave thicker finings of good fining power as in the case of tartaric acid.. Brewery preparations were also made by the rapid process using weight for weight citric acid in place of tartaric acid, but the finings though of normal viscosity, would not bring beer to such brilliant con dition as finings made with tartaric acid. If, possibly, the amounts of citric and sul phurous acid were suitably adjusted better results might be obtained. Since then, however, the position in regard to supplies of tartaric acid has eased and the matter has not been pursued further. Beers may be " fined out" or " fined down." The difference in action depends solely on whether or not gas is allowed to escape freely from the cask during the fining. The former process is generally used for mild ales and the latter for bitters. In "fining out" the coagulation must be fairly rapid, that is to say it should be complete overnight; but in "fining down" a slower coagulation is permissible, in fact, as pointed out above, fining in large floes may give trouble during the drawing of the beer. Although "fining down" does not require active evolution of carbon dioxide during the process, yet beers will not fine satisfactorily if they are in very low condition and, in this connection, the surface of the vessel is said to exert some influence. This is a matter on which it is very difficult to obtain direct evidence. Some public houses have metal or stoneware tanks as containers for beer, but these are generally used only for bright beer so that experience of the action of finings in these is not common. On the other hand fining in large glass-lined tanks in breweries is effective and yet here surface effect must be almost negligable. It is possible, however, that some beers fine more readily in a cask with a bare wood surface than they do in pitch or enamel lined casks. In normal beers yeast and amorphous matter in suspension provide ample surface to break carbon dioxide from supersaturated solution and so give that necessary life and movement to a beer which secures brilliant fining. War-time restrictions have denied to brewers the use of Russian and Saigon isinglass, yet beers have fined very well with mixtures of the less favoured varieties. This may in part be due to the fact that war time beers have been brewed with lower hop rates and with more nitrogenous materials, or rather with a lower proportion of " nitro gen diluents," both of which changes in brewing practice would make for easier fining, although the extra nitrogen might, on occasion, give a greater tendency to chill haze. It is open to doubt if the more highly

5 May-June, 1944] burns: the fining of beer 123 hopped pre-war bitters would have fined so brightly with the mixtures of isinglass now available. Fining difficulties have been attributed to the following causes: (1) Presence of wild yeast: bitter beer containing over 0-r> million cells of wild yeast per cc. will be hazy and will remain hazy after fining. No isinglass, nor any auxiliary material will fine a beer containing a heavy infection of wild yeast. In fact, from the practical point of view, a wild yeast can be defined as one which will not take finings. (2) Excess of primary yeast. If a beer is working actively it will not fine because clots are broken up before they can settle. When this activity has subsided it will often fine quite satisfactorily. In one case a cask of bitter beer with a yeast content of 30 million cells per cc. would not take finings, but when cask fermentation had subsided it fined tolerably bright. (3) Beer racked too clean. If finings are added to a beer containing very little suspended matter the resulting co agulation is so meagre that floating pieces arc apt to remain in suspension. Another form of this trouble is des cribed as "fining in layers," which is directly attributable to lack of con dition in the beer, but as this is usually due to a lack of yeast in suspension it can be referred to exceptional clarity at racking and can often be traced to indiscriminate use of copper finings. These faults, due to lack of yeast in suspension, may also occur when casks are allowed to stand for a few days imfined, then finings added and allowed to act without rousing up the yeast at the bottom of the cask. (4) Fining under pressure. If a cask is not vented during fining the beer may become heavily supersaturated with gas and when drawn the sudden rush of gas from the bottom of the cask disturbs the deposit and after at first running bright the beer becomes very piecy, or even thick. (5) Chill haze. This is due to cooling a beer below the temperature at which it was fined. Usually a drop of 5 to 10 F. will produce a haze which may persist after the beer is warmed again to the fining temperature. (6) Stubborn fining. Some beers, though free from wild yeast, and satisfactory as regards condition and content of primary yeast, will refuse to fine bright when newly racked. Some times the finings give a break, but the beer remains hazy. More usually there is no break and addition of finings seems only to increase the haziness of the beer. In these cases Irish moss auxiliaries may be helpful, but usually the best remedy is to keep the beer in cellar for a few days, rolling the casks daily and adding a little sugar priming. After some time the beer will take finings quite satis factorily. (7) Defective finings. Finings with a nor mal content of sulphurous acid are not liable to growth of bacteria or wild yeast, although these may survive in finings. A simple microscopic examin ation would show if finings were so grossly contaminated that they would be likely to affect the beer to which they were added. Mould may grow on finings left lying about in halfempty containers, thereby giving a bad flavour to beer. The defect which is most likely to arise in summer is that finings may become warm, in which case they thin perceptibly and lose much of their fining power. Clarification of beer by fining is a feature of present brewing practice and no substance " acts so effectively as isinglass. Although the process is not subject to any simple scientific explanation it works with great regularity and precision in all normal beers. All grades of isinglass work tolerably well, but there are small differences between isinglass from different sources which may be used to advantage to obtain the best results. The variations in brewing materials and in gravities necessitated by war-time restric tions have had little effect on the process of fining and have only served to confirm the established practice. In conclusion I desire to acknowledge the generous assistance I have received from Mr. Bernard Dixon in the preparation of this paper. Anchor Brewery, Mile End Road.London, E.I. An interesting discussion followed the reading of the papers.

2.8 Bentonite fining. Chapter: Clarification page 19 of 38

2.8 Bentonite fining. Chapter: Clarification page 19 of 38 page 19 of 38 2.8 Bentonite fining Bentonite fining is chiefly carried out to stabilize beverages against protein hazes. Grapes have a relatively high content of natural protein compared to other fruits.