STABILISATION stabilisation technology Clearly a matter of choice

It is said “people drink beer with their eyes”. An MAJOR important index of beer FEATURE stability is the visual Over the next appearance of the fourteen pages we product. With the address the issue of colloidal beer exception of a few well stability. known examples such as and weissbier, consumers from the raw materials will associate a star-bright inexorably product as a mark of polymerise over freshness. time and once the particles are big enough they will scatter light and By Chandra Gopal and cause a haze. The Mustafa Rehmanji challenge is for your International Specialty Products. beer to pass its best before date with a haze below 2°EBC. We have brought hilst a beer is likely to together experts in Wdeteriorate in terms of flavour the use of PVPP, before the appearance of haze, most silica gels, finings and gallotannins to consumers will probably notice the tell you how to latter first! The challenge is to achieve it. present a visually appealing product to the beer drinker, often some months after packaging. This long time frame is driven in many mature beer markets by a shift from draft beer consumption in bars to home- FIG. 1 below. Karl consumption from bottles and cans. Siebert has proposed A shelf life of six to twelve months that the two major is now common. proline, to which the polyphenols implicating the important role of constituents Ðhaze attach, as shown in Fig. 1. Another oxygen (either dissolved or as forming polyphenols Mechanism of non-biological model of chill and permanent haze oxidising agents) in colloidal and proteins - have haze formation development by O’Rourke proposed instability (Fig. 3). Many authors specific structures that When talking about haze, it is the driver in haze formation was the consider the oxidation of the dimers give them propensity to important to distinguish colloidal oxidation of flavanol oligomers to be the key factor in the attach and form haze from microbiological haze: the (sometimes also called flavanoids) development of chill haze. colloidal particles. latter being rare due to the during beer storage. As monomeric significant improvements in hygiene and dimeric flavanols such as control in breweries. Colloidal or catechin and prodelphinidin non-biological haze comprises polymerise, they have the capability mostly proteins, polyphenols, to bridge a number of proteins carbohydrates and rarely other forming a larger colloidal particle. minor constituents like starch, This is initially visible as a chill haze oxalate and hydrolysed heading due to the relatively weak hydrogen agent. The exact mechanism of haze bonds linking the two as shown in formation is still the subject of Fig. 2. With further polymerisation, academic investigation. Siebert larger molecules termed proposed that two major constituents tannoids are formed, which are more Ð haze-forming proteins and tightly bound to the haze proteins, polyphenols Ð have specific giving rise to permanent haze. structures that give them a Simple flavanols such as catechin propensity to interact and form per se, were not capable of haze colloidal particles. The haze proteins formation, but that same molecule have regions rich in the amino acid after oxidation, did produce haze,

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FIG. 4. As the lower molecular weight polyphenols increase in size through polymerisation, there is a significant increase in the rate of haze formation. A well stabilised beer is characterised by a long lag-phase, a slow rate of haze development and is still below 2¡EBC haze at the end of its shelf-life.

FIG. 2 top. O’Rourke et Achieving colloidal stability al proposed that simple Assuming that the freshly- flavanoids (flavanols) packaged beer has no detectable alone are incapable of tannoids present, during the initial causing haze; but storage of the beer there is only a following oxidation and slight increase in haze. As the polymerisation, the lower molecular weight -polyphenol polyphenols polymerise and complexes linked by increase in size there is a hydrogen bonds; significant increase in the rate of produce a chill haze at haze formation, as shown in Fig.4. 0¡C. If the hydrogen FIG.5. Options for beer stabilisation. The main stabilisation options are Hence effective colloidal bonds can be disrupted highlighted in terms of their mechanistic actions. Some of the advantages and stabilisation requires the removal by warming the haze re- drawbacks of each are summarised in Table 2 on page 17. dissolves. Tannoids are of the tannoids and a reduction in capable of forming the level of flavanols (particularly additional hydrophobic dimers and trimers) in conjunction into the fermentation vessel. A perhaps redissolve, so the beer and ionic interactions with haze active protein material. vigorous kettle boil and effective must be held around -1¡C into with acidic proteins, The extent of this reduction will hot and cold breaks will promote . The use of which are not disrupted depend on the shelf life early polyphenol-protein finings, green beer centrifugation by warming and result requirements of the beer, the raw precipitation. A rapid onset of and ‘tighter’ beer filtration are all in a permanent haze. materials used and the fermentation and early removal of options to improve beer clarity and procedures employed. Use of , preventing cell lysis are thus reduce the base complexes on FIG. 3 above. Simple stabilisers to achieve a target shelf important, as yeast mannans can which further haze material can flavanoids such as life should be optimised and not be contribute to the haze matrix. build. This ‘good brewing practice’ catechin are not capable excessive Ð as this is expensive and Oxygen exposure after initial wort will confer several months shelf of haze formation but may detract from beer quality. oxidation must be strictly life but with higher malt that same molecule after At each stage in the process, it is prevented and the beer at the end of contents and a shelf life in excess oxidation is an active important to pick out a few key fermentation chilled to -1¡C or of three months will demand some haze producer after strategies that can be adopted to lower for maturation. Maturation form of stabilisation treatment. interacting with protein. reduce the formation and passage time should be sufficient to allow of haze precursors to the next step the formation and precipitation of Options for beer stabilisation of the brewing process. In the protein-polyphenol flocs in the Since the two major components of brewhouse, avoiding the use of cold storage vessel. Having formed colloidal haze are the protein and weak worts can play an important these low temperature flocs, a polyphenol fractions, their role as these contain very high temperature increase above 0¡C reduction in beer prior to levels of polyphenols that can pass would cause them to separate and packaging is the obvious target.

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STABILISATION

wort clarification and polyphenol reduction by combining PVPP with κ-carrageen, Fig.6. The product is added directly into the kettle, or on transfer to the whirlpool. In use, better solid- liquid phase separation in the whirlpool has been noted in trials, with increased cold wort collection (Fig.7). A more ideal cone is often observed in the whirlpool, after wort run-off. In some instances faster fermentation rates have also been observed (Fig.8). The key FIG. 6. Combining PVPP with κ- Ð Polyclar Brewbrite provides objective is to increase the shelf- wort clarification and beer stabilisation with a single addition to the copper about 10 minutes before the end of boiling. life of the beer and using this simple procedure, a shelf life of 6 months or more (Fig.9) can be “The brewer’s Figure 5 shows the most common under the German Reinheitsgebot. achieved without the need for responsibility for options available to the brewer. The They are sometimes referred to as capital investment in the brewery. beer clarity does not list is not exhaustive, as it excludes ‘clean label’ products, as their end with packaging, some older technologies such as insoluble nature and removal from After packaging as the formaldehyde, which were no beer prior to packaging means The brewer’s responsibility for transportation and doubt very effective, but may they are not required to be listed as beer clarity does not end with subsequent storage leave behind toxic residue in beer. ingredients. packaging, as the transportation of beer can have a Probably the most widely Classically these treatments and subsequent storage of beer can employed products today are silica occur at maturation or filtration. very significant have a very significant impact on gel for protein stabilisation and However there is much current visual clarity. Excessive shaking impact on visual Polyvinylpolypyrrolidone (PVPP) interest in upstream beer (during transportation) may result clarity. Excessive for polyphenol stabilisation. The stabilisation where treatments are in fobbing and the appearance of a shaking (during other major product categories are added directly to the boiling wort collapsed fob haze or even transportation) may tannic acid and to spare for specialised equipment ‘particulates’ before the beer result in fobbing preparations (papain). like as slurry tanks and dosing reaches the customer. High and the appearance Both silica gel and PVPP have units at the end of the process. temperatures will accelerate haze of a collapsed fob the advantages of being insoluble Kettle finings in the form of κ- development. The standard haze or even in water and beer and are carrageenan is typically added ten temperature for some heat forcing ‘particulates’ before classified as process aids: as such, minutes or so before the end of the tests is often lower than ambient the beer reaches their use is permitted on a global kettle boil. A novel stabilisation temperatures in many developing the customer.” basis and specifically allowed agent harnesses the synergies of beer markets!

FIG. 7 above. Increase in wort yield with Polyclar Brewbrite. A better solid-liquid phase separation in the whirlpool aids wort run-off and improve yields without the need for trub-recycling and its negative quality impact.

FIG. 8 above right. Reduction in fermentation time with Polyclar Brewbrite. The combination of carrageenan and PVPP may decrease the time to rack gravity, without impacting the overall attenuation or flavour profile of the beer.

FIG. 9 right. Shelf Life of beer with Polyclar Brewbrite. The use of Brewbrite improved initial clarity compared to control and the predicted shelf life of the beer to around 6 months. In this instance, performance could be further enhanced by tighter beer filtration to produce an initial haze in the beer of <0.5¡EBC.

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 16 Effective colloidal stabilisation requires the removal of the tannoids and a reduction in the level of flavanols (particularly dimmers and trimers) ‘ in conjunction with haze-active protein material. Seven steps to colloidal stability ’ 1. Avoid use of very weak wort (<1.5 P) 2. Minimise oxygen pickup throughout the brewing process (<100ppb dissolved O2 in beer into package) 3. Cold store, transfer & filter beer at 0¡C, or below 4.. Wort & beer clarity are important Ð optimise finings, centrifugation & filter aid use 5. Ensure that the tannoids are removed from fresh beer and polymerised flavanols reduced by using PVPP. Reduce the levels of haze active proteins with silica gel, tannic acid or proteolytic . 6. Balanced upstream stabilisation is efficient and cost effective 7.. Consider beer transport & storage conditions

“At each stage in Table 2. Good brewing practice strategies to optimise colloidal stability. the process, it is important to pick Process Polyphenol Protein Process out a few key Reduction Reduction Optimisation strategies that can Raw material selection Low proanthocyanidin malt Low protein (N) Avoid excess malt be adopted to Hop extract barley modification reduce the Coarse grind of malt formation and Brewhouse High adjunct ratio Mashing process, pH Vigorous kettle boil for passage of haze Avoid weak worts & temperature >60 min. Avoid excess precursors to the Good hot break mineral salts next step of the Cold wort filtration brewing process. In Fermentation/ Rapid onset to Early yeast removal Minimum the brewhouse Maturation fermentation maturation at -1°C to form avoiding the use and settle hazes Filtration Low solids count weak worts can play Filter at -1°C an important role as these contain very Avoid O2 pickup high levels of polyphenols that can pass into the Table 3. Summary of the most widely used stabilising agents for preventing chill and permanent haze development in beer. fermentation vessel.” Stabiliser Action Advantages Disadvantages Dosage range

Polyvinylpolypyrrolidone Strong bonding Selective for Possible flavour loss 5 – 40 g/hl (PVPP) to haze-active haze-active if used in excess polyphenols polyphenols Capital cost for via multiple Single use or regeneration plant bonding Regenerable mechanisms Silica hydrogel Adsorbs haze- Selective for Higher usage rate 30 – 100 g/hl active proteins haze-active via hydrogen proteins bonding Silica xerogel As hydrogel Selective for Difficult to disperse 20 – 50 g/hl haze-active Reduced head proteins retention if Lower usage rate used in excess than hydrogel Gallotannin Adsorbs haze- Selective for haze- Beer losses if 4 – 10 g/hl (Tannic acid) active proteins active proteins used in tank by hydrogen Low usage rate Flavour harshness bonding if used in excess Papain Proteolytic Low usage rate Negative impact 1 – 6 g/hl enzyme – on head retention degrades proteins Persists in product by hydrolysis

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 17 STABILISATION

The use of polyvinylpolypyrrolidone (PVPP)

he unit molecular structure of PVPP dosage further yields a diminishing T closely resembles that of the amino return. acid proline Ð in fact it can be considered This means that stabilisation must be as a chemical analog of polyproline Ð balanced to achieve the most cost cross-linked polyproline. This structure effective reduction of both the polyphenol facilitates its ability to adsorb those and protein haze precursors. polyphenols responsible for haze development Ð both tannoids and PVPP in composite stabilizers polymerised flavanols. The adsorption of Products that combine both polyphenol polyphenols by PVPP is through and protein stabilisation efficacy are also hydrogen bonding between the proton widely available and include mixtures of donor from the polyphenol and the PVPP and silica gel such as Polyclar Plus FIG. 1. The adsorption of polyphenols by PVPP is through H- 730. These have the advantage of bonding between the proton donor from the polyphenol and carbonyl group from PVPP, together with π π convenience and effectiveness Ð only one the carbonyl group from PVPP, together with -bond overlap -bond overlap (delocalised electrons) (delocalised electrons) polar and hydrophobic reactions (13). polar and hydrophobic reactions. If that slurry is made for use and effectiveness is sounds complicated, in fact it can be enhanced. The beer treated with the easily explained by inspecting Figure 1. combined stabiliser provided the same Polyphenol adsorption is preferentially shelf life at a lower overall powder directed to the larger oligomers first as addition to the beer stream (Fig.4). This they have the highest number of potential can result in longer filter run lengths. A bonding sites to PVPP. The advantage to full-scale filtration and stabilisation trial the brewer is that the dosage rate of PVPP confirmed that the PVPP-silica product, can be adjusted to reduce the polyphenols Polyclar Plus 730, gave lower filter most likely to cause haze. Moreover, differential pressure and a longer run PVPP does not have any adverse effects length than the constituent components on beer quality including flavour or foam (Table 1). An explanation for this lies in stability. the capacity of the PVPP particles to help PVPP can be used either as a single-use FIG. 2. Tannoid reduction in an American lager treated with disperse silica particles and form a more PVPP. An addition of 10 g/hl resulted in >50% reduction in the stabiliser, or on a regenerable basis. PVPP uniform and permeable bed on the DE tannoid content of the beer. At 30 g/hl, the tannoid level was regeneration will become economical filter. below the limit of detection of the assay. when large volumes of beer are being stabilised. The single-use grade is micronised during manufacture to give a particle with a large surface area over which the polyphenols can be rapidly adsorbed. This allows low, cost effective addition rates to be employed - typically 10 Ð 20 g/hl. PVPP (and indeed silica gel) may be added at one of a number of stages in the brewing process after the end of ISP fermentation. An addition of as little as 10 g/hl resulted in a >50% reduction in the To enquire further about PVPP and FIG 3. Increase in the predicted shelf life of PVPP-treated tannoid content of a US lager (Fig. 2). combined stabilisation products contact beer. An addition of 20 g/hl achieved a shelf life in excess of Further increases, reduced this to below ISP at: five months in a US lager. A longer shelf life can be achieved ISP Europe by the application of a protein stabiliser such as silica gel. the detection limit for the assay (10-12 Waterfield, Tadworth, Surrey, UK mg/l PVP K-90). The resulting increase KT20 5HQ in shelf life was also dramatic, with a 20 Phone +44(0) 207 519 5054 or go to the g/hl addition rate providing a predicted international web site to find your local office shelf life in excess of 5 months in this www.ispcorp.com beer shown in Fig 3. Increasing the

Table 1. Increase in filter run length with combined application of PVPP and silica gel as an admixture – Polyclar Plus 730. The mechanism of action is considered to be that the PVPP disperses the silica and enhances the permeability of the DE filter bed, leading to a lower filter differential pressure over time and a longer run.

Stabiliser Addition ∆p/hr Filter Run rate (g/hl) (hr) FIG 4. Stabiliser application and predicted shelf life. In Xerogel only 36 0.49 6.4 brewery trials, the admixture of PVPP and silica Ð Polyclar PVPP only 13 0.35 7.4 Plus 730 Ð gave cost-effective reductions of polyphenol and Polyclar Plus 730 33 0.25 12.0 protein by a single addition to the beer stream without the need for specialised equipment.

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 18 Silica-based colloidal stabilisation

The chemical proteins haze-active, but this also characteristics that make enables the selective removal of proteins and polyphenols sensitive protein from beer by silica haze-active are the same gel, Figure 1. Tannoids as defined by Chapon features that enable their are those polyphenols that selective adsorption from precipitate with PVP beer by silica-based (polyvinylpyrrolidone). These are stabilisers. This article flavanoids formed from the describes the structural monomeric flavonols catechin, features of these so- epicatechin, gallocatechin and called sensitive proteins epigallocatechin. Their structure is likely similar to the polymeric and tannoids and brings proanthocyanidins, prodelphinidin this together with the B3 and procyanidin B3. These features that make silica- polyphenols have vicinal hydroxyl based stabilisers (OH) groups on their aromatic rings, effective in assuring the which makes them haze-active but shelf life of beer. also enables their selective removal from beer either by PVP-coated silica gel, or PVPP. By Sonya Broderick Ineos Silicas Silica gel and protein adsorption heinheitsgebot and FDA Silicas are broadly classified R approved silica-based according to their water content as stabilisers are, through the selective ‘xerogels’, ‘semi-hydrogels’ or adsorption of haze-forming ‘hydrogels’. Generally the term (sensitive) proteins and polyphenols ‘xerogels’ refers to silica gels having within the silica pores where the Figure 1 top. Amino (tannoids) used to assure the shelf a loss on drying of about 25% or concentration of hydroxyl groups is acid composition of haze and foam protein life of beer. Their amorphous less, while hydrogels have a loss of highest. The molecular size of and the proline structure structure makes them safe to handle 60% or more. Semi-hydrogels lie sensitive proteins requires that silica (Asano, 1982). while control of density and particle between these. The different has pores of sufficient size to allow moisture contents of silica gels gives the protein to enter and adsorb to the size distribution, enables Figure 2 above. Silica stabilisation to be made either at rise to differences in the density of surface through hydrogen bonding the powders so that low-density with the hydroxyl groups. Figure 3 gel structure maturation or at the filter. Using (Matsuzawa and xerogels are dusty powders, while shows that optimum protein these products, cost savings in Nagashima, 1990). respect to brewing capacity may be higher density semi-hydrogels and adsorption is attained with silicas realised either through reduced hydrogels are generally free from having maximum surface area in maturation times, extended filter run dust. pores in the range 3Ð12 nm (30-120 lengths or partial replacement of Amorphous silica gels used in the Angstroms). Adsorption follows a kieselguhr filter powder. brewing process have small particle Type I adsorption isotherm, size (ca. 10 to 30 microns) and are indicating monolayer coverage. Interactions in beer between The author sensitive proteins and tannoid highly porous having surface areas The solids content of the silica, from about 300 m2/g to more than the particle size and number of Sonya Broderick was polyphenols can form a visible 2 recently appointed colloidal haze that limits a product’s 700 m /g. These are hydrophilic accessible hydroxyl groups Applications Leader for shelf life. Reducing the powders due to coverage of their determine adsorption capacity. Thus INEOS Silica’s global beverages business, her concentration of either one or both surface by hydroxyl (silanol) groups, on a gram for gram basis, for a given (Figure 2). It is the interactions of pore structure silica xerogels provide responsibilities include of these haze precursors serves to management of technical prevent haze formation and assure a proline with these groups that enable greater protein adsorption than service to brewing product’s shelf life. the selective adsorption of sensitive either semi-hydrogels or hydrogels. customers and the design protein from beer. Another important property of and implementation of Effective protein binding occurs silica gels is their permeability, or projects to optimise Sensitive proteins and tannoids customer’s stabilisation Sensitive proteins range in size from requirements. 10 kD to 30 kD, are heavily Table 1. Permeability controlled silica gels To learn more about the use glycosylated with glucose and of silica based stabilisation agents call John Leake on represent 3Ð7% of total beer protein. Hydrogel Xerogel 1 Xerogel 2 Xerogel 3 +44 (0) 1925 416000 or In contrast to foam proteins, [email protected] Average particle 18 12 12 12 sensitive proteins are rich in the www.ineossilicas.com size (microns) amino acids proline and glutamic Permeability 0.15 0.12 0.04 0.002 acid. It is the presence of proline, (D’Arcy) with its ring structure and prominent carbonyl group, that makes these

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 19 STABILISATION

Figure 3 above. Protein filterability. Proper control of adsorption versus silica particle size distribution can give surface area in the 40- rise to a range of permeable xerogels 120 Angstrom pore size and hydrogels that can be used either range at maturation or filtration, Table 1. hydroxyl adsorption sites than PVPP can be reduced. Thus brewing Figure 4 above right. PVP-coated silica gel and and is thus effective in adsorbing capacity is effectively increased Schematic of PVP- tannoids adsorption only the most haze-active without capital expenditure. coated silica showing Polyvinylpyrrolidone (PVP) is a polyphenols. Because both PVPP Typical dosing rates for silica carbonyl adsorption water soluble polymer that is made and PVP-coated silica use the same hydrogels to assure stability lie in sites as yellow markers. insoluble in beer either by type of polymer, they essentially the range from about 50g/hl to attachment to an amorphous silica adsorb the same haze-active 150g/hl, dependent upon the carrier, Figure 4, or through cross- polyphenols. required shelf life requirements, linking to form polyvinyl (poly) beer quality and the use or pyrrolidone (PVPP). Application to the brewing otherwise of other stabilising aids. process The low density of xerogels does PVP interacts with tannoids through To assure colloidal stability, it is not not however exclude their formation between necessary to remove all of the application at maturation. These can the vinyl carbonyl group and the sensitive proteins or tannoids. provide more rapid, and greater, polyphenol hydroxyl groups. The Identification of a tolerable level of protein adsorption than hydrogels number of accessible carbonyl these can be used to define a beer and might serve to further reduce adsorption sites on the PVP dictates composition at packaging delivers maturation time. Xerogel does polyphenol adsorption capacity, satisfactory haze stability. however have a lower settling rate Figure 5 below. while selectivity for haze-active Concentration of either of the haze than hydrogel so that a proportion Colloidal stability polyphenols is determined by precursors can therefore be high in may carryover during transfer to diagram. competitive adsorption. Thus beer as long as the other is low, filtration where it would be removed polyphenols having high numbers of Figure 5. Consequently stabilisation together with other beer solids. Figure 6 bottom. Protein hydroxyls adsorb most readily and costs per hectolitre can be balanced Stabilising beer at the filtration adsorption during most strongly. by using appropriate combinations stage can increase process maturation. PVP-coated silica has fewer of stabilisers to remove sensitive flexibility. The decision concerning proteins or tannoids. stabilisation of a particular brand All of the products discussed can can be taken at this last stage of the be used either in maturation or at the process to coincide with packaging filter. The selection of product and and sales demand. application point is influenced by Engineering narrow particle size the brewery’s powder handling distributions produces controlled systems and process set-up. permeability silica xerogels and The difference in density between hydrogels. Maintaining a small silica xerogels, semi-hydrogels and particle size provides for fast hydrogels in turn affects the rate of protein adsorption and substitution settlement of the powders in liquid. of lower permeability silica gels can Thus, when added to the maturation extend filter run length and reduce vessel hydrogels will settle, in filter aid demand, Figure 7 (page accordance with Stoke’s law, more 22). rapidly and cleanly than xerogels When applied at the filter, silica despite the latter becoming hydrated gel retains adsorption capacity for a when added to beer or water. prolonged period so that it actively Hydrogels added to the maturation removes protein across the filter run. vessel settle rapidly to form Thus to maximise flexibility the compact sediment. Protein dosing of silica can be reduced as adsorption rate is quite high and filtration proceeds. This reduces the adsorption capacity is reached in silica demand and the solids loading less than 24 hours (Figure 6) so that on the filter and makes the when maturation is employed to stabilisation process more cost remove chill haze, maturation times effective.

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STABILISATION

more expensive than silica gel and Slurry make up time is typically in are generally used to extend the the order of 20 minutes, although it stability of beer for export. In this may be necessary to extend this way the brewing process can be time to break any lumps that might made more flexible to fit with have formed in the product during changing packaging demands as transport and storage. orders are updated. The products Silica xerogels and PVP-coated are sometimes applied in silica are prepared as a 10-15% w/v maturation when particularly suspension, typically requiring no ‘difficult to stabilise’ beers are more than 10 minutes to disperse. encountered. Used in combination Both slurries have low (water) with silica gel the extended contact viscosity over a wide range of shear time can serve to increase the rates. For stabilisation at the filter Figure 7. Benefit of Typically xerogels are used from product’s effectiveness. Typical any of the products can be prepared permeability controlled about 15g/hl to about 40g/hl, usage rates for these products are in in the same tank as the body-feed (PC) silica gel on filter although there are examples of the range 5g/hl to 20g/hl. filter aid. If not required for run length. using these at more than 60g/hl. As immediate use, a flow of carbon with hydrogels the precise loading Dosing of the stabilisers to dioxide or nitrogen may be bubbled depends upon a number of beer through the suspension to prevent influences. The stabilisers are dispersed in cold oxygen ingress. After use, the Most often PVP-coated silica and de-aerated water using a low speed mixing vessel, pipework and the PVPP are applied at the filtration impeller to minimise aeration injection system should be stage, where they can be applied before dosing to the beer. Silica thoroughly flushed to avoid together with silica gel if required. hydrogels and semi-hydrogels are blockages with any residual This is because these products are prepared as a 20% w/v suspension. stabiliser or filter aid. The use of clarification aids

“Carrageenan is the At the end of primary Carrageenan clarification aid of fermentation beer Stoke’s Law: Carrageenan is the clarification aid choice for clarifying contains large quantities v = 2(ρs-ρl).r2.g of choice for clarifying wort. It is wort. It is used of yeast and suspended 9µ used throughout the brewing world and also extensively in the food throughout the protein/polyphenol brewing world and Where, industry as a thickening, stabilising particles. The techniques also extensively in v = rate of sedimentation of a and gelling agent. the food industry as used to remove these are particle Carrageenan is a high molecular a thickening, filtration, centrifugation ρs = density of the particle weight polysaccharide made from stabilising and and, for traditional cask ρl = the density of the liquid repeating units of galactose and gelling agent.” ale, sedimentation under r = the particle radius anhydro-galactose, either sulphated gravity. g = acceleration due to gravity or unsulphated (fig.1). About 25,000 µ = viscosity of the liquid of these units are linked in a linear form to produce a biopolymer. By Brian Evans Three isomers are present, A B Vickers lambda, iota and kappa Ð the latter gravitational force, low liquid being active in the role of larification aids are used to viscosity and low relative density. clarification. Key to its performance Cassist in the removal of these The point to note is that only two in both the brewing and broader food suspended solids by the process of factors are of practical significance application, is the ability of this flocculation. As a result the brewer in the brewing process Ð particle size isomer to form gels. benefits from improvements in and gravitational force. Carrageenan is produced from red filtration or centrifugation, or in the Clarification, in the context of the seaweeds, Rhodophyceae. This is case of cask ale, sedimentation article, means increasing the rate of collected and dried, and then speed. sedimentation. Stoke’s Law undergoes a sequence of alkali Stoke’s Law is helpful in demonstrates that this can be washing and rinsing which both understanding the action of achieved by the use of agents that cleans the weed and also increases clarification aids. It defines the rate increase particle size Ð clarification at which a sphere (yeast or protein aids, or gravitational force Ð the particle) falls through a liquid (beer centrifuge. or wort). The clarification aids in common use Simplified, the factors that result can be divided into carrageenan, for in the fastest rate of sedimentation wort, and isinglass and auxiliary are large particle size and finings, for beer. Fig.1 Structure of kappa carrageenan.

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 22 Fig.2 far left Performance comparison of carrageenan from Chondrus crispus and Euchema Cottonii.

Fig.3. Particle size analysis showing the effect of carrageenan on the removal of proteinaceous particles The benefits of this clear wort are seen in easier beer filtration and improved cask ale the ability to form gels. The use of carrageenan to form strong gels clarity. Brewers originally used When added to boiling wort, kappa when cold, aided by the presence of unprocessed seaweed of the species carrageenan reacts strongly with K+ and Ca2+ , that underpins the Chondrus crispus (Irish Moss) to soluble proteins, notably the proline- clarification action. good effect. However, the rich haze precursor fraction. Direct The result of using carrageenan is a developing interest in products for reaction between soluble proteins clear wort, with reduced use in the food industry resulted in and carrageenan, particulate proteins concentration of proteinaceous the establishment of species high in and carrageenan, and perhaps both, particles (fig. 3) the kappa isomer. Euchema Cottonii occurs. However, only when the Carrageeenan is added to the is now the main species. It is farmed treated wort is cooled does the kettle, preferably just before the end commercially, mostly in the shallow, carrageenanÐprotein complex of the boiling stage. Sufficient time warm waters of Indonesia. Its role as precipitate out of solution. This is needed for dispersal and the most cost effective method of feature is important when trying to dissolving, and a ‘10 minutes rule’ wort clarification is undisputed understand the action of has been adopted as the norm. (fig.2) carrageenan. It is the tendency of Carrageenan is supplied in three

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 23 STABILISATION

Fig. 4 right. Effect of wort pH on carrageenan activity.

Fig. 5 far right. Effect of isinglass on the removal of wort proteins, compared with carrageenan.

forms Ð powder, dust free granules, dissolved and added to beer the and tablets. Each form has its collagen molecule attains both advantages and adherents. Powders The first positively and negatively charged can be suspended as a slurry in cold processing aid sites. The overall charge is positive, water and automatically dosed via Collagen from Russian and because of this it becomes metering devices. Granules can be sturgeon had been the attached to negatively charged yeast added manually, or via pneumatic traditional source of isinglass cells. Reaction with proteins is systems. The tabletted form of for brewing. An eight fold thought to be as a result of co- carrageenan has the benefit of increase in price in the late precipitation with this yeast- containing a dispersant. It can 18th century encouraged collagen complex. The deficiencies “The interaction therefore be added later in the chemist and inventor William of this simple explanation are Murdoch to develop local between process, directly into the wort exposed by the observation that receiver or whirlpool. sources. For 15 years these isinglass is a powerful clarifier of suspended beer were used by British brewers solids and cold wort. (Fig 5) Clearly there are Carrageenan treatment rates until, in 1809, their no yeast cells present to initiate isinglass is authenticity as a beer The correct treatment rate varies clarification, and the pH is complex and not ingredient was challenged in from wort to wort, but is typically in significantly different to that found fully understood. court by Customs and Excise. the range 1Ð 3g/hl. Certain factors of beer. The accepted Murdoch won the case. impact on the function of Recent work has shown that the theory is that Amongst his arguments were carrageenan, for example grist that although it was added to helical structure is more important in when it is make-up, malt quality, brewing the action of isinglass than is its dissolved and beer, his isinglass was liquor treatment, and wort pH removed during clarification overall positive charge. added to beer the (fig.4).It is good practice to identify and was, therefore, not an Whatever the mechanism, collagen molecule the ideal addition rate using a simple ingredient. isinglass can flocculate and sediment attains both optimisation test, and repeating this yeast cells, protein particles, or both, positively and after any major raw material or to an extraordinary degree. When negatively process change. added at a typical rate of 15 mg/l charged sites.” imino acid initiates hydrogen (dry weight) it is able to remove Isinglass finings bonding within the molecule, which greater than 95% of suspended yeast Isinglass is arguably the processing is important in maintaining the cells and greater than 90 % of aid with the longest history of use in helical structure. More importantly protein particles of haze forming brewing. Of the clarification aids it for the brewer, it is these bonds that size.(Fig 6) It has been calculated is most probably the most studied, endow the molecule with its that this equates to removing around and in terms of understanding how it clarification properties. 30 times its own dry weight of works, perhaps the least understood. The interaction between suspended suspended solids. It has been used for cask ale beer solids and isinglass is complex clarification in the UK for at least and not fully understood. The Using isinglass 300 years. Its ability to remove not accepted theory is that when it is Traditionally used as a clarification only yeast but proteinaceous Fig. 6 right.. Particle particles has meant that it also finds size analysis of beer application as a pre-filter treatment, with and without the and is regularly used in conjunction addition of isinglass. with centrifugation. Isinglass is obtained from the swim bladders of tropical and sub-tropical fish. This provides the industry with an extremely pure source of collagen. Isinglass collagen is a fibrous protein which occurs in a rigid, rod- like triple helical structure Ð a biopolymer. It has a characteristically high proportion of hydroxyproline in its makeup. This

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 24 Auxiliary finings and isinglass are antagonistic and must not be mixed prior to addition to beer. The actual reaction time between auxiliary finings and protein particles is small and only a minimal ‘ time need be allowed before isinglass is added.

aid for cask ales, isinglass is now Fig. 7. The effect of increasingly used as a pre-treatment auxiliary finings on beer for filtered beers. In either ’clarity and sediment application it is added at the end of volume when added fermentation. It is regularly added to prior to isinglass the beer stream after centrifugation. finings. Here, its ability to remove small protein particles that may have passed through the centrifuge is utilised. Isinglass must be added via an acidified solution. In this form it is viscous and needs thorough and immediate mixing after addition to beer. Maximum effect can be gained if it is added continuously in-line to the beer stream. Addition rates vary from one beer to another, and are best determined empirically. Typical rates for cask ales are in the range which carry a strong net negative The action of silicate based finings “Attention should 3Ð6 g/hl, and for filtered beers 1Ð3 charge. As with isinglass, the can be thought of as being based on be given to g/hl. mechanism is little understood. It is electrostatic attractions, enhanced establishing a Isinglass is available in three main undoubtedly an over-simplification by the tendency for the silicilic acid balance between forms. The choice of which to use is to state their action is based solely unit to form gels in beer. a rate that is dictated by the fact that the collagen on the attraction to positively The overall net negative charge sufficient to molecule needs to be dissolved in charged proteins. Clues can be renders the silicate-protein complex achieve the acidic solution before use, and in this gained, however, from observations attractive to isinglass. These excess desired clarity, state is unstable at temperatures made when silicate auxiliaries are charges may, however, at high above 15¡C. Ready to use liquids are added to beer: addition rates cause repulsive forces but not so great ideal where there is a local supply ¥ At low addition rates they show to come into play, resulting in as to cause and where usage dictates short stock limited flocculation and poorly formed sediments. Whatever unduly bulky holding, or where there is availability sedimentation. Beer haze is the mechanism behind their action sediment of cold storage. In all other situations often increased. Any solids they certainly give extra clarity to volumes.” finely milled powders or pre- removed are predominantly beer when used in conjunction with hydrated, temperature stable pastes proteinaceous. isinglass, along with much faster are more suited. ¥ At increased rates the degree of rates of sedimentation. flocculation and sedimentation Auxiliary finings and isinglass are Auxiliary Finings increases, some improvement in antagonistic and must not be mixed As the name suggests, auxiliary haze is observed. prior to addition to beer. The actual finings are used in conjunction with, ¥ At these higher rates the reaction time between auxiliary and in support of, another sediment becomes bulky. finings and protein particles is small clarification agent Ð isinglass. They ¥ At very high rates excellent and only a minimal time need be were developed to help produce cask clarity can be achieved as a allowed before isinglass is added. In ale that had fast settlement times and result of the removal of yeast as practice this interval is anything a high degree of clarity. well as protein particles. between minutes and many hours. As with carrageenan and isinglass ¥ At these rates the flocculated Because of the great variety of their action relies on their polymer solids hardly settle, forming a auxiliary products on the market it structure. They are supplied as loose and very voluminous is not possible to give a typical To learn more about the acidified solutions of silicate, matrix. addition rate. These have to be use of finings agents call Brent Jordan on +44 (0) 1283 polysaccharide, or combinations of ¥ Isinglass works better in beers ascertained empirically. Attention 563268 or both. The silicate based products treated with low rates of should be given to establishing a [email protected] make up the majority of a wide auxiliary finings. balance between a rate that is www.lallamand.com range of products and the remaining ¥ The speed of flocculation, and sufficient to achieve the desired section will concentrate on them. settlement speed in beers treated clarity, but not so great as to cause The silicate auxiliaries are a with this combination of finings unduly bulky sediment family of dilute silicic acid solutions is significantly enhanced. volumes.(fig. 7)

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 25 STABILISATION Gallotannins in the brewery

Gallotannins are natural polyphenols, they were one of the gallotannins. The most difficult the first agents used in beer stabilisation. They were part of gallotannin production is the introduced to the scientific and practical brewing fractionation to yield the correct molecular weight for match the world by Prof. Jean de Clerck just after the Second point of addition in the brewery. World War. Tannic acid, the day-to-day name for The crude extract is a mixture of gallotannins, is used in most brewery laboratories to molecular weights from 180 to over determine sensitive proteins in Lundin fraction assays. 2500 daltons (near the solubility In the 1960s tannic acid was introduced by a large limits). In general the molecular brewery in the States and another in the Netherlands weight should increase as the for protein stabilisation. gallotannin is used later in the brewing process. addition to a protein-floculation aid “Gallotannins, pre- By Roger A. Mussche dissolved in water, Belgian Fine Technology International and thus a colloidal stabiliser on the At mashing-in may be added in the protein-side. Specific molecular weight brewing water or gallotannins, (SMW.TA) such as proportionally oday, gallotannins are selected Gallotannins Beerotan Q (as supplied by BFTI) injected at the T on a tighter molecular weight Gallotannins are extracted from can be used up-stream in the mixing point of the basis and so different grades of gallnuts (Chinese or Aleppo), sumac brewing process. Gallotannins, pre- water and the grist. tannic acid can be applied at several leaves, tara (Caesalpinia spinosa) dissolved in water, may be added in Further addition stages of the brewing process, up- and teri pods (Caesalpinia digyna) the brewing water or proportionally stream at mashing, in the kettle as or even from cell culture. They all injected at the mixing point of the may be made to the well as down-stream. Their have a polygalloylstructure on a water and the grist. Further addition sparge water.” functionality is unique and multi- central molecule like glucose. may be made to the sparge water. functional including metal- The extraction of the ground and Figure 1 describes the advantages chelating, aldehyde-binding, LOX- pelletised raw material is done with for the flavour stability and colloidal management, they have a reducing solvents including ethyl acetate stability. The -protein and radical scavenging effect in which is particularly selective for interaction is given in the

Figure 1.

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 26 A word about proteases Various peptidases have long presented a cheap opportunity to prevent chill haze in beer. Enzymatic degradation by papain acts by a different mechanism altogether to the options described elsewhere in this feature in that it actually breaks down haze proteins, preventing any Figure 5a. Figure 5b. polyphenol-protein complexes from becoming sufficiently large to scatter mechanism figure 2. Gallotannins at wort boiling can also result in longer filter runs. light and thus form visible The impact of an early and in the whirlpool Similar results are obtained by haze. Papain is a mix of gallotannin addition on beer ageing Tannic acid at specific molecular addition of SMW.TA at transfer to peptidase enzymes and more specifically, on iso-α- weight (SMW.TA) added at a rate of the whirlpool. Table 1 (below) extracted from the papaya acids degradation, is unequivocally 2 to 6 g / hl during wort boiling, is an shows that the use of SMW.TA in the fruit; this enzyme ‘cocktail’ positive as seen in Figures 3 and 4 easy tool to produce a pre-stabilised copper gives approximately 50 % of has the significant which shows the decay of total beer (Figure 6). The gallotannins the stabilisation using HMW.TA in disadvantage of being bitterness and the degradation of are reacting with sensitive proteins maturation. non-specific, that is it will various iso-α-acid isomers. and metals to form a more solid cone break-down all proteins, In the figures, beer C in the whirlpool. Furthermore, its Gallotannins at filtration including the foam- corresponds to the control beer addition is a very useful aid to The most economical and easy way positive ones. As the without gallotannin dosage, shorten maturation time and to to apply gallotannins is the addition enzyme is not de-activated whereas beer D was prepared with reduce the precipitate formed during of HMW.TA to the beer into the by usual pasteurisation addition of gallotannins to the maturation. When added at the end filter where it gives good temperatures (in fact it brewing and sparging liquor (10g/hl of wort boiling in the right dosage, it performance for precipitate capacity increases in activity during and 5g/hl, respectively). Both the process) foam stability brewing trials were performed will deteriorate over time. Hence, it should be used under comparable conditions with care. (mashing-in at 62¡ C and pH 5.7). We have seen that the Furthermore, it is remarkable that haze sensitive proteins the addition of gallotannins results contain significant levels of in a significantly lower amount of the amino acid proline in phenylacetaldehyde, furfural and their molecular benzaldehyde. Apparently, composition, these gallotannins can inhibit the de novo originate from the proline formation of these aldehydes during rich hordein (alpha gliadin) wort production (see Fig. 5a and fraction of malted barley. 5b). The pyrrolidine ring makes In support of the analytical the protein chain more results, flavour assessment of the rigid and adjacent peptide gallotannin treated beers was bonds lack a hydrogen on pronounced better after forcing the amide nitrogen thus storage at 40¡C the carbonyl group preceding the ring is a strong hydrogen bond acceptor and will readily form a bond with the hydroxyl groups on the condensed polyphenols. DSM Food Specialities have launched Brewers Clarex which incorporates a proline specific protease derived from Aspergillus niger. Trials over 13 months storage at IFBM in France indicated superior performance against a ABOVE: Figure 6. control brew treated only with PVPP. Flavour and RIGHT: Figure 7. foam were unaffected.

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 27 STABILISATION

Table 2 right. Fig. 8 far right.

and clarity. Guidelines for filtration fractionation of beer proteins on the treatment) was also added 5 minutes conditions are given by the basis of their iso electric points, before the end of the boil. manufacturer. The benefits of whereas Table 4 demonstrates the The effect of both products is HMW.TA addition before end effect of HMW.TA on the sensitive remarkable on the sensitive proteins filtration are summarised in Figure 7. proteins, but this is only an example and the proanthocyanogens. A Table 2 summarises the filter of one study; a combined application patented combined product will conditions, but tailor-made advice of HMW.TA Ð PVPP is also soon be on the market. can make the solution even more included. The increase of the total polyphenols economical. Gallotannins can also block the with ± 20 ppm is mainly associated chain of aldehydes formation by with the analytical method, in fact How gallotannins react and chelating metals like Fe3+ and Cu2+. the increase is between 3 and 7 ppm. implications for beer stability The formation of aldehydes in aging The haze sensitive proteins are beer is measured with the thio Some special cases generally recognised as the proteins barbituric acid (TBA) agent over precipitated by gallotannins. intervals of 20 days. The results Combinations of gallotannins If we can remove the most sensitive presented in figure 8 clearly To demonstrate the influence of raw group of cationic proteins with an demonstrate the effectiveness of materials and stabilisation methods isoelectric point (Ip) of 5.3, we will gallotannins with regard to beer on different beer parameters a lot of obtain a “protein-side” stable beer flavour stability. In conclusion, combined work was done. (with a slight increase of the final gallotannins are, as a bio-product, Table 6 shows some representative beer pH by only 0.1 is based on the again in the centre of interest for data obtained by measuring total same principle of cation- brewers (specific action, no solid polyphenols or polyphenolic stabilisation). Table 3 shows the waste, high resistance to staling fractions in two different beers, (RVS), shelf-life supporting, etc). stabilised with gallotannins, gallotannins + PVPP (combined Combination of products stabilisation) and PVPP respectively. A novel approach is the use of It’s nice to see that the control SMW.TA and PVPP at the end of brew with the polyphenol free hop boiling. extract has half the level of The advantage of such a polyphenols as the control brew procedure includes the removal of bittered with hop cones. The hop sensitive proteins, the removal of extract control brew has lower levels sensitive polyphenols of total polyphenols, flavanoids and (proanthocyanogens). Both are anthocyanogens than the hop cone easily removed at the whirlpool brew after any of the treatments in leading to a very clear wort and a the test faster start to fermentation. There is less sediment during maturation and Comparison of different methods more effective end filtration. A study was carried out to obtain a The addition is carried out at the calculated comparison between most end of the boiling: of the stabilisation methods, based ¥ 5 minutes before the end Ð on results with Tannometer Ð PPT SMW.TA (Beerotan Q) is added analyser as described by Schneider from a 5 % water solution. & Raske. ¥ 3 minutes before the end Ð Fig. 9 shows the comparison (based PVPP (Polyclar 10) is added on PPT-analysis) between the from a 5 % water slurry. different ways of beer stabilisation. Table 5 (over the page) Table 7 is the legend to fig. 6. demonstrates the effect of both It is important to note the by-pass products. As reference 10 g / hl operation for CSS and PVPP filter Daraclar 7500 (Grace Davison SHG plate systems: the level of stability is

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 28 Table 5

Total Flavanoids Proantho- Sensitive Cold haze Polyphenols as catechine cyanogens Proteins 5 days 40 °C To find out more about (mg/l) e.g. (mg / l) mg / l EBC 1 day 0 °C EBC the use of gallotannins in the brewing process, Control 221 45 44 9.5 6.0 contact PVPP (15 g / hl) 170 38 38 9.0 5.0 Roger Mussche at SMW.TA (5 g / hl) 240 46 39 4.0 4.0 Belgian Fine Technology PVPP(15)/ SMW.TA (5) 200 37 36 3.5 2.0 International Leenstraat 8, 9070 Daraclar 7500 (10 g/hl) 220 43 42 9.0 5.0 Heusden Belgium Tel: +32 (0)9230 3533 Fax: +32 (0)9231 8941 e-mail: [email protected] controlled by gradually reducing the developed to produce a stable haze with 25 %, increases the reducing volume of beer going through the in white beers, at a range of 10 Ð 20 power for a better flavour stability by-pass thus stabilising a higher ppm. and gives an improved mouthfeel to percentage of the throughputs, as the the beer. The dosage rate is 180 mg adsorption sites are occupied. New Ð a special case per kg of grist and is added with the However, such systems are ActiBREWTM is a natural brewing water. This new product is controlled from preset calibrations; condensed tannin extracted from available from BFTI. the problem is how to perform real- carefully selected cocoa beans. It time measurement of stabilisation. leads to a faster brewing process and In conclusion has a positive effect on the colour Gallotannins are used through the Haze-makers and taste of the beer, without whole process of brewing. As a Separate gallotannins, (like leaving any residues. It also natural processing aid, gallotannins Beerotan H) has been specially improves the lauter-tun performance are used for colloidal stability, shelf-life improvement, better lauter-tun performance, improved end-filtration with trub removal in the up-stream process The latest generations as super- gallotannins can be applied in the down stream process of brewing without residue. Special analytical methods are developed with enzymes, as tannase and HPLC to evaluate the processing aid residues.

Beerotan is here Calling all brewers interested in a sophisticated range of gallotannins There are four different formulations to suit your addition point

The Beerotan, H,Q,R and S range comprise super gallotannins made from four different gallnuts to obtain the ideal blend of molecular weights for effective protein removal at varying points of addition in the brewing process from mashing in to filtration.

Call Roger Mussche at Note: Belgian Fine Technology International on -Polyclar 730 is a blend of 70 parts of Xerogel and 30 parts of PVPP ++32 (0) 9230 3533 for details -Brewbrite is a mix of carrageenan and PVPP [email protected]

The BREWER & DISTILLER ¥ Volume 2 ¥ Issue 6 ¥ June 2006 ¥ www.ibd.org.uk 29