Beer processing Choices, choices Beer processing and filtration In this article, I will keep away from repackaging information readily available in manufacturer’s brochures and look at the practical choices and decisions that brewers are faced with when considering beer processing and filtration by Paul Buttrick Beer Dimensions I make no apologies for reminding readers of the basic physics behind filtration Whatever decisions are made and technologies used, Darcy’s Law from 1856 will always apply – the secret is to find ways of improving processes and look at innovative ways to approach the equation Developing his law and applying it to beer filtration: Flow rate = Permeability factor × Pressure drop × Area of filtration surface Filter bed thickness × Liquid viscosity Pressure Drop across a filter bed = Flow rate × Filter bed thickness × Liquid viscosity Permeability factor × Area of filtration surface Applying this equation, it is easy to see how filter design effects beerfiltration Maximum pressure drop allowed across a filter Modern filters using filter aids are designed to work up to bar inlet pressure, thereby increasing a filter run because they can operate at a high differential pressure Crossflow filters which not use filter aids have large surface areas and a very thin film which makes up the filter bed on a membrane surface Filter area Increasing a filter’s surface area is key to a well performing filter no matter what technology is used Experience has pointed to specified flow rates for different types of filter with plate and frame filters running typically at 3.5 hl/m2/h, vessel filters at 5-7hl/m2/h, and kieselguhr free crossflow filters are slower at 0.5 – 1.0 hl/m2/h Filter cake thickness This is dependent on the solids content of the beer and dosing rate of bodyfeed powder Breweries which install centrifuges reduce the solids presented to the filter, are able to make large increases in filtration performance and 10 Conical vessels and pipe fences at Früh in Cologne capacity Crossflow filtration works because the filter bed thickness is very thin when compared to a traditional kieselguhr filter Beer viscosity Better brewhouse procedures and malt specification to reduce beta glucans in the wort, sometimes with the aid of added beta glucanase, have reduced filtration problems due to high viscosity beer – however problems are not unknown, if they are, they are not widely distributed Permeability The pressure differential across a filter bed is determined by the permeability of the filter Brewer & Distiller International • February 2010 • www.ibd.org.uk bed, which is dictated by the size and porosity of the filter powder The amount of solids in an unfiltered beer will affect the bed thickness and permeability of the filter bed on all types of filter Ways of improving filtration Traditional cold conditioning involved many days storage at reducing temperatures down to below 0°C In the process, beer flavour develops, yeast drops out and complexes of proteins and tannins form and sediment to improve a beer’s shelf life and haze stability Modern large breweries have reduced cold storage times to single numbers of days at -1°C or lower with high gravity brewing and Beer processing Above: Two 400 hl/hr rated GEA Westfalia ‘green beer’ centrifuges at a large brewery in Germany Right: The new Alfa Laval Brew2001 direct drive centrifuge on test in a European brewery use aids such as PVPP and silica gels to give long shelf-life, thereby saving valuable time and capital for installing tanks With order of magnitude estimates for cold storage in a 500,000 hl/annum brewery for week costing £5–7 million, but rising to £30–40 million with eight weeks, it is easy to see why traditional methods of long, slow cold storage periods have disappeared from all but the most traditional breweries or those that have tanks and cellars to spare So unless you have large amounts of cash, or are wedded to tradition as a USP, or maybe truly believe long conditioning gives a better, more harmonious drinking beer, installing centrifuges is a viable option On the topic of ‘does traditionally conditioned beer taste better?’ I’ll sit on the fence, and even after 30 plus years I don’t know the answer, except there are some lovely beers out there from both sides of the argument If I had a brewery with excess tankage, I’d at least have a go with brewing a premium traditionally conditioned beer and taste and judge the results for myself times by installing centrifuges rather than increase tankage Does it go between Fermentation Vessel (FV) and Cold Storage Tank (CST) - so called ‘green beer’ centrifuges, or between Cold Storage Tank (CST) and filter? I did not think there was much debate on where to put a centrifuge until I faced the question in a previous employment with a global brewing company The standard was for installing centrifuges after CST, before filtration My knowledge in the UK suggested positioning the centrifuge between FV and CST Discussing the issue with the centrifuge suppliers was very helpful – we can either and the choice is yours! It seemed to me that positioning a centrifuge between FV and CST would give the following advantages: 1) Reduced solids in CST, hence much longer filter runs, reduced down-time, less filter aid usage and reduced losses Where should a centrifuge be positioned? With beer solids being fundamental to the efficiency of filtration, it is easy to see how centrifuges have become popular So we’re short on tank and filtration capacity and the decision has been made to reduce process Valves, valves and more valves Far left: The ubiquitous valve array at Carlsberg in Denmark Left: Tuchenhagen valves at Quinn’s bottling facility in Cheshire Above: Sudmo valves at CUB, Yatala Brewer & Distiller International • February 2010 • www.ibd.org.uk 11 Beer processing Membrane filtration The GEA Pall ProFi system in operation at Carlsberg in Denmark .and at MillerCoors, Shenandoah USA A Puresep installation for cider filtration at UBL in Ledbury, UK The Alfa Laval membrane filters at Tucher in Nuremberg, Germany 2) Consistently reduced solid loads going to the filter and longer runs would allow better planning for filtration and packaging with less packaging down-time It ticked all the ‘supply the customer on time’ boxes 3) Any issues with oxygen pick up from centrifuges was much reduced since there was time to rectify any centrifuge issues Then I heard other arguments as to why the centrifuges should be positioned after CST just before filtration 1) There would be the advantages of longer filter runs, less downtime, as with the alternative option 2) Because yeast was still present in reasonable quantity in the Cold Storage tank, the maturation process and diacetyl reduction would continue throughout the cold storage period, possibly leading to consistently lower diacetyl levels in the finished beer 3) Modern centrifuges are more reliable than early versions, so worries about breakdowns and oxygen pick up are much reduced 4) Some breweries have had filtration problems with prematurely blocked filters due to high pressure differentials on relatively 12 clean beer with low yeast counts So what did we do? Well, as all brewers do, we carried out some trials which showed that filtration benefits were exceptional in both situations and there was no issue with early blocking of filters due to premature high pressure rises, so the decision was made to install centrifuges between FV and CST Incidentally, having to install only two centrifuges instead of three was another significant factor in this decision Everything was going well until six months after installation, when horrendously short filter runs were experienced – oh dear After much head scratching, sampling and analysis etc, focus swung on to two areas: timely tank bottoms removal and brewhouse practice in relation to wort clarity Going back to basics and reintroducing ‘best practice’ in both areas solved the problem and no more short filter runs were experienced So what would I advise if asked? Well, I think I would sit on the fence with the centrifuge manufacturers and a reasoned analysis of both options in relation to the particular brewery, brands and company philosophy, overall project cost and Brewer & Distiller International • February 2010 • www.ibd.org.uk work out a decision from there I am told that Bass in the late 1970s, obviously with plenty of money, used both a green beer centrifuge ex FV and a larger diameter, tighter plate pack and faster machine after the CST Isinglass finings are still sometimes used to aid sedimentation of tank bottoms before filtration It is a simple, low cost (that is little capital outlay) option but thought must be given to losses and handling tank bottoms sedimented with finings, which can be difficult to recover beer from The main suppliers of modern centrifuges are Alfa Laval, which manufactured the first centrifuge over 125 years ago and GEAWestfalia who celebrated 100 years of beer centrifugation in 2009 About 50% of machines installed are green beer centrifuges with this figure increasing over the last 5–8 years Both companies have continually increased the size and sophistication of their machines, with an emphasis placed on operational efficiency and reliability backed up by a drive to reduce energy and water costs For example Westfalia have introduced the GSE 550 centrifuge to the market with a Beer processing one-metre diameter bowl and is in the process of introducing a direct drive machine with optimised pumping and frequency inverters Alfa Laval presented their new Brew 2001 eDrive centrifuge platform incorporating a new direct drive mechanism at Drinktec 2009, which will reduce energy and maintenance costs considerably as well as give a modular design flexibility Alternatives to cold storage An alternative is to look at other stabilisation options I am an advocate of always processing beer at a lower temperature than it is served at, so for me cold storage and proper stabilisation with long periods of time, and/or silica gel and PVPP treatment is currently the best way of ensuring a good haze stability However, science moves things on and the use of a proline-specific endo-protease enzyme marketed as ‘Brewers Clarex’ by the Dutch company DSM has the potential to revolutionise brewer’s views on stabilisation DSM say that by adding Brewers Clarex to wort at the beginning of fermentation that subsequent cold storage times can be reduced or even eliminated and temperatures increased compared to current practice Brewers are very conservative when making changes that effect final beer quality, it will be interesting to see how things have developed if I write a similar review article in a couple of years’ time What are the options for filtration ? Again its down to choices, and since my last review in 2007, more informed choices are available, but they are not necessarily any easier to make! Kieselguhr-free cross-flow filtration The major players Norit (BMF – Beer Membrane Filter, currently in 25 breweries) and Pall (Profi) are still very much promoting the ‘green’ and quality benefits of kieselguhrfree crossflow filtration and have an increasing number of installations around the world mainly in collaboration with large brewing companies Alfa Laval with Sartorius equipment are still involved, but to a lesser degree and have three plants in China, Sweden and Germany Swiss company Filtrox on the other hand are not yet promoting crossflow for beer filtration, although they use ceramic membranes on their Cerinox filters to recover beer from tank bottoms Listening to various sources, I get the feeling that the financial justification for installing a cross-flow filter are not yet fully proven and justifications produced to show total lifetime costs rely on figures that tend to prove or disprove whatever system the presenter is championing Norit introduced their new BMF-18 filter at Drinktec in 2009 This filter works on the same principle as their original filter, but with less hardware and components, allowing the Capex to be significantly reduced Less complexity also results in lower beer losses, and less water usage A large Norit crossflow filter showing modules each of 10m2 and hl/hr flowrate There have also been significant improvements to CIP, resulting in a reduced need for chemical cleaning which is replaced by less demanding water back-flushes The BMF-18 is so called because is is made up of skid mounted units of up to 18 modules, giving 150 hl/hr filtration flowrate This offers a very flexible approach which can be easily uprated by adding modules and/or skids Whatever the financial situation, there is no doubting that kieselguhr-free filtration using crossflow will feature more in beerfiltration in the future To this, the costs must demonstrably reduce to win the argument The cost and reliability of membranes is still under scrutiny and there is a view that a ceramic or more robust membrane needs to be used to increase reliability, with a guaranteed membrane life of ten years compared to the current two Norit’s approach to this issue is to have a fixed financial guarantee for membrane cost, as opposed to a fixed time guarantee Another way to reduce costs on cross-flow filters is to reduce the number of modules used, thus making them smaller and cheaper to make and renew Back to Darcy again, increasing the filtration area of a module by reducing the diameter of the capillaries will achieve this Norit has reported improvements in flavour stability on beer filtered on their BMF (EBC Venice); this is attributed to lower iron (due to the absence of kieselguhr) and dissolved oxygen levels in the beer The debate over the need for a centrifuge before a crossflow membrane filter continues as before with Norit continuing to work without a centrifuge, relying on a retentate tank to recover beer solids and Pall using GEA-Wesfalia centrifuges to remove as much solid material as possible before final filtration and polishing on the membrane filter The debate is highly technical, on the one hand, installing a centrifuge must incur significant extra cost, but the beer presented to the filter will always be much cleaner and should mean that a small filter can be used Norit say that companies already using ‘green beer’ centrifuges not need an extra centrifuge before the membrane filter Both companies are constantly improving their equipment with an emphasis on lower water and beer losses Traditional bed filtration The advent of crossflow was thought to signal the end for installing traditional filters using powder regimes This is not happening and high investment costs plus the other current uncertainties of crossflow means that many brewers still opt for more conventional systems Plate and frame filters are still being installed in remote situations where simplicity rather than technical sophistication is still prudent Candle filters, once thought to be outdated are the predominant filter type used for both primary beer and PVPP stabilisation Screen filters are still popular in Asia, but the simplicity of candle filters with no moving parts and improvements to the candle design has been very popular The leading candle manufacturers are Filtrox with their Synox filter and Krones with their TFS (Twin Flow System) Filtrox had their best sales ever in 2007/8 whilst Krones have sold nearly 100 TFS filters since 2002 The candle diameter of the Filtrox Synox is about one third less than previous designs This has enabled more candles to be installed within the filter vessel, thus significantly reducing the earlier disadvantage of a high filter volume compared to filtration area Krones reports an improvement in beer filterability of beer brewed from plant which includes internal dimple heating elements on their ShakesBeer conversion vessel The improvement is thought to be due to differences in particle size distribution in the mash Brewer & Distiller International • February 2010 • www.ibd.org.uk 13 Beer processing A view above a 400hl/hr Pall CFS sterilising filter at Cölner Früh in Cologne, Germany A Krones TFS kieselguhr filter running at 400hl per hour in the Vietnam Brewery , Ho Chi Minh city, China The future for Kieselguhr The future for kieselguhr is not as grim as had been predicted by some, mainly among those who promote kieselguhr free processes Speaking to Matt Jordan of World Minerals (Celite brands) there is still plenty of good quality kieselguhr in deposits around the world His main defence was that kieselguhr still gives the best most consistent beer clarity results Due to the production processes used, it is can be made in any number of different grades which makes it very flexible and able to be used in response to brewing problems such changes in malt quality The emphasis is now on customer service where suppliers work with brewers to optimise their use of filter powder to bring down overall filtration costs This involves selecting the right grade for the job as well as reducing usage, by matching dosing rates to beer solids Spent kieselguhr disposal is still a potential issue, with soil injection still the main option, although using it in composting and incorporation into building materials is being looked into Kieselguhr-free filter powders There appears to be two approaches to the kieselguhr-free world in the brewery, one being crossflow filtration, the other being development of kieselguhr-free filter aids It seems to have gone quiet on this latter idea and I’m sure we would have seen more in the brewing press if major breakthroughs had been achieved However A-BInbev has been working on a kieselguhr-free filter aid for some time and many of their breweries either use it, are doing trials or are set up for its use 14 Although it is an ‘in-house’ development at the moment, it remains to be seen whether it will be used solely for internal commercial advantage or will eventually be sold to others BASF, the German chemical conglomerate, have developed a filter aid called ‘Crosspure’ for filtration of beer and other beverages A paper on Crosspure was presented at the IBD Africa Symposium in March 2009 by Filtrox AG It is a safe, easy to handle and regenerable material, produced by compounding polystyrene (70%) with PVPP (30%) to form a filter aid with high chemical and mechanical stability Polystyrene is extensively used in food packaging whilst PVPP is well known for its beer stabilisation properties, so at first sight looks to be a ‘brewer’s utopia’ material At present it comes in two grades, mid range finer Crosspure F (permeability >170 mDarcy) and Crosspure XF (permeability >100 mDarcy) Crosspure can be used in a similar way to kieselguhr with similar dosing rates, but because it has different flow properties, adjustments have to be made to filters to handle the material The changes are in relation to particle distribution in order to get an even filter bed Both the Filtrox Synox and Krones TFS filters can be adapted to change from kieselguhr to Crosspure use The flow characteristics of the TFS – using external circulation and Synox using internal circulation can be optimised for use with Crosspure Other equipment required is plant for filter aid regeneration The filter aid regeneration process involves a number of steps including: rinsing with 85°C hot water; cleaning with 2% caustic solution; rinsing with water Brewer & Distiller International • February 2010 • www.ibd.org.uk followed by an enzyme treatment (40–50°C at pH 4–5); a further treatment and pH adjustment process It is a lengthy process taking 4–5 hours and is similar to PVPP regeneration, with the 2% caustic and post rinse taking place on the filter elements prior to the enzyme treatment in a separate vessel As in all production processes, down time is wasted production time, so I am sure reductions in regeneration time will be forthcoming Losses during regeneration are said to be similar to PVPP regeneration at about 2% In 2007 I reported on a new development by KHS called Kometronic, incorporating a regenerable precoat filter replacing kieselguhr with cellulose fibres Despite enquiries, it seems things have gone quiet on this method as well, so I assume that developments continue but at a slower pace What about smaller/micro brewers? With more microbrewers investing in bottling lines, there is a proliferation of bottled beers on supermarket shelves – those of you in the north of England will be amazed at the range available at Booths supermarkets The micro brewer has a number of choices; go to a recognised processing and packaging company (like Robinsons, Camerons or Daniel Thwaites in the UK); go to one of the new smaller bottling lines or some simply fill their own beer directly into bottle and sell it as bottle conditioned The larger contract breweries are tending to set minimum packaging lengths – say 75 hl, which is more than many microbrewers wish to deal in Bottling beer yourself as a bottled conditioned beer is very artisan, but many beers become infected and turn sour and it becomes very labour intensive when sales go well So what options does the small brewer have? The key for them is to have a process that is straight- Brewers Clarex™ COMPLEXITY IS A CHOICE ™ BREWERS CLAREX FOR SAVINGS THAT CLEARLY MATTER Are you looking to reduce energy bills, increase production capacity and minimise environmental impact? Do you want to achieve this while making your brewing process less complex? Then look no further than Brewers Clarex™ A natural, proven, sustainable concept, Brewers Clarex™ offers an easy way to prevent chill haze formation in beer With its unique properties, Brewers Clarex™ responds to the key brewing challenges – profitability, consistent DSM Food Specialties info.beer-ingredients@dsm.com www.dsm-foodspecialties.com www.brewersclarex.com quality and sustainability – by removing the cold stabilisation process What’s more, no extra equipment is necessary so cost savings are immediate Choose Brewers Clarex™ to efficiently stabilise your beer, improve profitability, increase production capacity and reduce CO2 footprint – with no additional financial investment Discover the unlimited capabilities of Brewers Clarex™ Beer processing Diagram of the new unfiltered beer distribution in Filtrox’s latest SYNOX candle filter forward to apply, is cost effective and, most importantly, gives the right quality results A major problem is that beer may be bright and clear at room temperature, but as soon as it gets near a fridge, a chill haze emerges which becomes permanent after a few weeks The artisans might say ‘so what’ but in my (and most of the beer drinking public’s) mind, only beer which is supposed to be cloudy such as a Hefeweizen should be cloudy, other beer should be bright So rule number one for small breweries is to chill stabilise beer correctly, which means ensuring the beer is held at or below zero for a number of days, and don’t forget that beer is densest at 3°C, so cooling jackets and temperature probes at the top of a tank may show a -1°C, but the beer will still be warm at the bottom Another opportunity may be to use Brewers Clarex Filtration options are difficult because equipment used in larger breweries is expensive and oversized The attention and technical input to filtering beer commercially on a small scale can be too easily underestimated As with large filter plants the laws of physics still apply and must be A new kieselguhr and PVPP Filtrox SYNOX filters rated at 400 hl/hr installed in a modern Chinese brewery considered when selecting a process and equipment There are two main options for primary filtration, whilst cartridge filtration is most commonly used for final polishing and ‘sterilisation’/biological stability As with all filtration the amount of solids being presented to the filter will define filter run length As a general rule if the solids are not to be reduced before filtration, a traditional powder/filter aid process should be used This could involve a simple plate and frame filter using a number of smaller frames where flow rates are about 3.5 hl/m2/hr A polishing/’sterilising grade’ sheet filter can be incorporated in the same frame with flow rates of 1.5hl/m2 An alternative to open style plate and frame filters are vessel filters, which could include screen filters, cartridge filters and perhaps consideration of ‘Nellie’ filters, which were used to clarify beer recovered from tank bottoms when I worked with Whitbread These from British Filters Ltd, Plymouth Devon are prepacked filters rated at 100 hl/hr, smaller Nellie minors are 30 hl/hr, and consideration is being given to producing a ‘Micro Nellie’ for use in microbreweries rated at 7–10 hl/hr These would seem ideal for small breweries, with no messy kieselguhr handling, with regeneration/backwashing taking place after 250 hl and A roughing filter rated at 30 hl/hr suitable for use in a microbrewery repacking at the factory 16 Brewer & Distiller International • February 2010 • www.ibd.org.uk at longer intervals Filters can be supplied from normal rough beer clarification to beer ‘sterilisation’ duties Vessel filters offer an alternative to plate and frames with Velo from Italy manufacturing a full range of horizontal and vertical screen filters ranging from 2–100m2 Smaller filters, ideally sized for small breweries up to 5m2 (25 hl/h), are horizontal screen design, whilst the bigger units up to 100m2 (500hl/h) are vertical screen filters Pall filtration is offering fully enclosed systems for use by smaller breweries Filtration takes place on a fully housed modular lenticular depth filter system called SUPRAdisk II The SUPRAdisk elements come in a variety of grades suitable for dealing with differing quality beers Housings can be adapted to suit a variety of throughputs and the number elements can be altered to give increased flexibility The option of using finings to clear beer before filtration is an attractive one for small brewers The clarified beer is then filtered using a standard sheet or membrane cartridge filter This method is quite successful if well managed, but finings and filters are not happy bedfellows if settling time is not enough or if any sediment is allowed near the filter, because not enough tank bottoms have been removed; losses can also be high ■ ■ Acknowledgements I would like to thank those companies who have supplied information for this article; always a difficult ask when the deadline comes at Christmas You can contact the author at: Paul.Buttrick@Beerdimensions.com ... volume compared to filtration area Krones reports an improvement in beer filterability of beer brewed from plant which includes internal dimple heating elements on their ShakesBeer conversion vessel... www.ibd.org.uk 11 Beer processing Membrane filtration The GEA Pall ProFi system in operation at Carlsberg in Denmark .and at MillerCoors, Shenandoah USA A Puresep installation for cider filtration. .. but they are not necessarily any easier to make! Kieselguhr-free cross-flow filtration The major players Norit (BMF – Beer Membrane Filter, currently in 25 breweries) and Pall (Profi) are still