The visual appeal of what we eat and drink has a major effect on the mind of the consumer. For most consumers a bright clear liquid is preferable to a cloudy one. In recent years there has been a movement among some craft brewers to promote cloudy, or less bright, beers with arguments that the flavour, for whatever reason is somehow better. However since many of these brewers do not understand the practical application of finings or do not possess the technology for filtration their disdain for beer clarity would appear to be very convenient.
The vast majority of beer sold is bright and clear and its clarity is considered an extremely important attribute.
To produce a bright cask conditioned beer the brewer is totally dependent on the use of finings for clarification. The production of brewery conditioned beer is less dependent on finings. However many brewers choose to use both kettle finings and isinglass finings, and sometimes auxiliary finings, for pre-filtration clarification. Even where brewers have turned their back on the use of isinglass finings in favour of centrifugation etc. as pre-filtration treatments, most continue with the use of kettle finings.
To achieve the best fining results it is important to consider the whole system from the choice of raw materials to the design and operation of brewing equipment along with the choice of finings, as well as the dose rate and dose method. Furthermore it has been shown that optimising clarity at each stage in the process will help considerably to produce the most consistent and best clarity at least cost.
The exact mechanisms of wort and beer clarification are still not fully understood. This is undoubtedly due to the complex nature of wort and beer chemistry. However, sufficient of the critical factors are well enough understood to allow a better use of finings than was the case even as recently as thirty years ago.
The pre-history of finings is inevitably pure conjecture but it is possibly easier to see how Irish moss found its way into beer or wort than it is to imagine how acidified fish swim bladder found its way into beer. The monks who constituted most of the scientific community of medieval times reputedly used Irish moss to clarify wine, beer and honey. At some point fish swim bladders must have been subjected to the right set of circumstances which revealed its clarification potential.
Historically kettle finings were flakes of a particular seaweed, Irish Moss, Chondrus crispus. However most kettle finings in use today are produced from Eucheuma Cottonii – mostly grown in warmer countries such as the Philippines. The active compound is the polysaccharide kappa carageenan. It is manufactured in granular, powder or tablet form, the tablets having about 40% active ingredient with the rest binding and effervescing agents.
As recently as the 1920s kettle finings were described as removing “protein bodies” and were thought of as an auxiliary finings for beer (Harman et al. 1927:203). More recently by the 1980s it was suggested “that carrageenans stimulate the precipitation of solids both in the hot wort and the cold wort” (Mathews 1986: 384). Kettle finings were reported to be responsible for the coagulation of fine particles into larger particles or flocs which then readily sediment as well as the reduction in the level of wort proteins (ibid). The reaction between kettle finings and soluble proteins alongside the reaction between kettle finings and non microbiological particles to create flocs were reported by (Vernon 1984:25),(Montgomery 1986). With (McMurrough 1985:93) indicating that kettle finings react with the proteins most likely to be involved with chill haze formation. Two papers examining firstly the molecular basis of wort clarification (Dale 1995:285) and looking at the mechanism of action of kettle finings (Dale 1996: 285) confirmed that kettle finings reacted with soluble polypeptides and with non microbiological particles to create flocs. They also put forward the importance of the change in carrageenan to a helical structure on cooling to enable reaction with these particles.
The importance of kettle finings as part of a complete fining pre-filtration system was now beginning to make better sense and there was confirmation that removing hot break and cold break at the relevant stage of the process was important to the later successful filtration and even beer stability. Producing a well-coordinated finings system requires the optimisation of each stage. Currently the practical way of predicting the optimal choice and addition rate of kettle finings is to carry out a series of tests on samples of wort, with the brightest supernatant and the lowest level of sediment indicating the optimal result (Thompson 1994). However there is hope for a more general predictive test with some work carried out by (South 1996).
Many of the early published papers on isinglass focus on the manufacture of isinglass from fish swim bladders. The importance of the choice and quality of the swim bladders is discussed (Berry 1907) along with the choice of cutting acid or acids, the time to cut, temperature control and the mechanical mixing (Burns 1944). This was obviously a process fraught with problems and pitfalls for the unwary brewer who would easily end up with substandard isinglass which would inevitably lead to poor beer clarity. The advent of isinglass floc and shred considerably improved the brewers chances of successful isinglass manufacture with a more rapid and even cutting process. The different fining ability of isinglass made from swim bladders from different sources was correlated with differences in the molecular size of some of the constituent collagen molecules (Leach 1967) and that longer molecules produced better fining results (Leach and Barrett 1967). The positive charge on isinglass attracted to the negative charge on the cell wall of yeast is set forward as the principal reaction of isinglass in beer as reported by (Wiles 1951: 84) which also explains the inability of isinglass to fine wild yeast. This same principal reaction is confirmed by (Vickers 1974: 19) and by (Taylor1993: 202). However there is a more recent hypothesis that the “soluble collagen reacting with a soluble beer component to form loose, fluffy flocs which as they form, first enmesh and then interact with yeast and non-biological particles to form tighter dense flocs which sediment to leave bright beer” (Leather 1994:432). This would help to explain why the same isinglass addition rate for a certain beer remains the same despite the yeast count varying from 0.5 to 2.0 million cells per ml. The levels of fine particles in beer have been shown to have a considerable effect on sediment volume and beer clarity. When these non-biological particles have been categorised into three fractions namely below 2 micron, 2 to 10 micron and above 10 micron it has been shown that the optimum fining performance is obtained when all three categories contain about one million particles per ml. If the beer contains too few particles while good initial clarity is obtained the sediment is loose and if disturbed the resettlement clarity is not as good. If the beer contains too many of these fine particles a greater volume of sediment is produced and initial clarity is poorer and any improvement is only possible with the addition of auxiliary finings (ibid). The only way to identify which particular isinglass blend to use and which auxiliary to use, if an auxiliary is required, and what the optimum dose rates are, is by empirical trials. This involves a series of tests on the beer and a visual determination of the clarity and sediment (Thompson 1994:474). The method of addition of isinglass to beer is of considerable importance to achieving the optimum result. However a compromise in favour of a simple system rather than a better much more complicated addition system is usually the practical solution. Adding finings to chill and filter beer should be done proportionately to the flow of beer during transfer. The finings should be diluted to as low a viscosity as is practicable and the point of addition should be at a point of turbulent flow. The same procedure is preferable for addition to cask by adding isinglass proportionately to the beer passing to the cask. However the normal compromise is to fill the cask, leaving enough space for the isinglass and then to squirt the isinglass into the beer filled cask. This improvement of performance due to the rapid and complete dispersal of isinglass in beer to achieve the best possible result is further confirmation that the initial reaction of isinglass in beer is more likely to be with a rapid reacting soluble component than with the yeast cell wall (ibid).
Auxiliary finings appear to react with and remove positively charged soluble material which would otherwise compete with isinglass, or indeed to react directly with isinglass itself to initiate the formation of flocs necessary for fining action. Polysaccharide and silicate auxiliaries react differently in beer and so it is likely that both mechanisms apply (Leather 1994:432) and as observed this would vary from beer to beer.
There is general agreement that a coordinated approach to fining is required to obtain the optimum result both for cask beer and for pre-filtration treatment of chilled and filtered beer. This approach is well presented in both (Leather 1998) in the 1996 Cambridge prize lecture and in the Brewers Supply Group (BSG) “Wort and Beer Clarification Manual” written by Ian L Ward. While there has been some further progress towards understanding the mechanism of kettle finings (Dale 1995), (Dale 1996), the BSG manual and the aforementioned 1996 Cambridge Prize Lecture together contain the most comprehensive presentation of how finings work and how they should be applied. It should be noted that the BSG manual relies heavily on previous research carried out and methodology employed by Savilles Clarification. This is embodied in the statement:
It has been demonstrated empirically, and has generally been accepted as best practice,
to remove particulates at as many stages of the brewing process as practical, since this
gives a more efficient and consistent process. In the case of cask beer, considerably
brighter beer is obtained using this principle than if all the clarification is left to the
post-fermentation stage. For filtered beer, both longer filter runs and lower post
filtration hazes are obtained (Ward, 2014)
Moreover, it is borne out by several observations including for example, the inclusion of Leather’s observation of the mechanism of kettle finings whereby the carrageenan in kettle finings can react with both soluble proteins and insoluble proteins in separate reactions, in the latter case leading directly to flocculation and in the former leading to first a soluble carrageenan-protein complex and then an insoluble carrageenan-protein complex. Furthermore, Ward makes an explicit recognition of the derivation of these ideas from Leather’s Cambridge Prize Lecture.
The whole concept of finings is under serious attack after many hundreds of years of service to the brewing industry. Concern has been raised at the possible allergic reaction to any remaining traces of fish collagen in beer treated by isinglass. Vegan vegetarians who have a very loud voice for such a small group have managed to persuade Diageo, the owners of the Guinness brand to stop using isinglass and instead use centrifugation. There is no mention of how much more expensive this treatment will be in both monetary and energy terms. Once brewers stop using products like isinglass the likelihood is that they will never restart and yet another part of the tradition of British and Irish brewing will have been lost. It will be interesting to see if the use of isinglass persists elsewhere in the world. In a recent paper on filtration choices (Boulton and Quain 2008) there was no mention of any finings as a pre-filtration treatment and the only pre-filtration treatment recommended for consideration was tannic acid.
After many hundreds of years of successful use of seaweed extract as kettle finings and isinglass as beer finings the mechanisms of these agents and how beer chemistry interacts with them are more clearly understood. There are still many aspects which need further investigation but for now the level of knowledge available in support of finings means that brewers using them can be confident of a reliably successful and low cost clarification system.
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Berry AE (1907) The Manufacture of Brewers’ Finings. J. Inst. Brew. 13: 44-65
Boulton C, Quain D (2008) Making Choices. Brewers Guardian, May: 24-28
Burns JA (1944) II The fining of beer. J. Inst. Brew. 50: 119-123
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Taylor R (1993) The Fining of Cask Beer. The Brewer. May: 202-205
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Vernon PS (1985) Wort Clarification. The Brewers’ Guardian. 3:25-28
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Ward IL https://bsgcraftbrewing.com/Resources%5CCraftBrewi… [Last Modified 11 Feb. 2014]
Wiles A (1951) The Action of Finings and its Relation to the Electrokenetic Properties of the Yeast Cell. European Brewery Convention Proceedings of the 3rd Congress, Brighton. 84-97
Written by our head brewer Alistair Thompson (Hillstown Brewery)