IN PRACTICE
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GERMAN PURITY LAW
CONFORM STABILISATION
It needs to be admitted: Stabifix is a strong supporter of the German Purity Law idea. More than the – disputable – restriction of raw materials, there is a clear understanding of what is a raw material or a processing aid or an additive. It is admirable to see brewers using their complex brewing process as an organic purification, clarification and stabilisation process in its own. Stabifix is proud to be recognised as a competent supporter of brewers to maximise the processing benefits over minimized application of processing aids and omission of additives.
It needs to be admitted: Stabifix is a strong supporter of the German Purity Law idea. More than the – disputable – restriction of raw materials, there is a clear understanding of what is a raw material or a processing aid or an additive. It is admirable to see brewers using their complex brewing process as an organic purification, clarification and stabilisation process in its own. Stabifix is proud to be recognised as a competent supporter of brewers to maximise the processing benefits over minimized application of processing aids and omission of additives.
STABILISATION AT FILTRATION
The simplest and most common method is to use STABIFIX stabilisers at the final beer filtration. In this case it can be added directly via the kieselguhr dosing unit. The required rate depends on the desired shelf life. It normally varies between 30 and 100 g/hl, for Stabiclear there would be a limitation of 50g/hl.
Higher rates of STABIFIX silica gels are needed where beers with high hop rates are to be treated, whilst ordinary lager types need lower rates. As STABIFIX silica gel also acts as a clarifying filter aid, the kieselguhr dosing rate, mainly the portion of fine kieselguhr, can be reduced up to the amount of STABIFIX silica gel added.
The required contact time of STABIFX silica gels with beer is relatively short and usually exists in all common filtration equipments. A longer contact time is can be achieved by dosing the STABIFIX stabilisers from a second dosing unit – for example in the storage cellar – into the beer stream prior to a buffer tank. This would be to the benefit of the Stabiclear (PVPP) performance but is not really necessary for the silica gel products. An extra dosing unit is advisable in those cases where different beers are being filtered and stabilized, because the STABIFIX stabiliser dosage can then be adapted exactly to the beer type and stability requirements without affecting the kieselgur body feed.
STABILISATION AND PRECLARIFICATION AT BEER TRANSFER
It is possible to add STABIFIX stabilisers directly to the storage tank as practised with other stabilizers. In this case silica gel has to be added to the beer as an aqueous suspension when the beer is pumped from one storage tank to another. Most of the STABIFIX stabiliser portion is then eliminated by sedimentation.
For application in the transfer process a special type of STABIQUICK has been developed: STABIQUICK SEDI. This material consists of xerogel and high swelling sodium-bentonite. An important advantage of this product is easy mixing with water to form a suspension, which is free from lumps. This then allows a quick formation of a compact sediment.
The stabilisation process in the storage cellar can be applied likewise during transfer of the beer from fermenter to storage tank. Then the sedimentation of STABIQUICK SEDI occurs together with the yeast. In this case, however, a secondary stabilisation at final filtration will probably be necessary, in order to remove also the haze forming particles from the beer which had additionally been formed during chilling.
All STABIFIX stabilisers can be applied at fermentation or maturation stage, but there is a particular advantage in doing so for the tank stabiliser STABIFIX SEDI to pre-clarify the beer and for STABICLEAR PVPP, which benefits from increased contact times, delivering up to 20% more adsorption compared to filtration application.
It should be noted, that the effectiveness of STABIFIX stabilisers is increased, if all standard procedures, which enhance beer stability and which are known to the brewer, have been applied in order to achieve an optimum stability before the actual stabilisation. In this respect a long, cold storage period is usually advantageous. In those cases where no long and cold storage is possible, STABIFIX stabiliser have proven to be a useful means of compensation.
STABILISATION AND PRECLARIFICATION IN THE BREWHOUSE
Experiments with the STABISOL process during the past years have led to a large number of observations. However, it is still not possible to give exact advice on the use of STABISOL in an actual case of filtration difficulties in a brewery without preliminary tests. At 0° C, increasing quantities of STABISOL of 25, 50 and 100 ml should be added to the beer to be filtered; after subsequent precipitation and removal of the precipitate, the beer should be tested for filterability.
If STABISOL is not successful at maturation stage, it can also be applied in the brewhouse, especially if high haze lautering is observed. Wort treatment at laboratory scale can give good indication of the efficiency, that can be expected in the real brewing process. The obvious evaluation criteria is the appearance of the hot wort and the wort during cooling after the separation of the hot trub together with the STABISOL precipitate. In such a case, however, industrial scale tests are the only means of obtaining definitive results since this is the only way to properly record the other production conditions and their influence on the later filterability of a beer.
It is often observed that beer cannot be filtered brilliantly, even with the finest kieselguhrs. Without any pressure increase the filtrate does not become clearer than 1 – 2, often 3 – 4 EBC units. In these cases, an application of 5 – 10 ml/hl STABISOL to the body feed enhances the clarity. The fine haze of the so formed silica gel accomplishes a tighter kieselguhr filter bed. Consequently, the clarity amounts to 0,3 – 0,5 EBC and pressure increases with 0,2 – 0,4 bar/h. Some brewers have adopted filtration regimes using coarse particle size DE or filtration aids with reduced surface area, and manage the sharpness and differential pressure of the filter through the controlled inline addition of STABISOL.
CLASSICAL COMBINED STABILISATION WITH PVPP
It is known that the adsorption effect of STABIFIX silica gels towards protein-polyphenol compounds of the beer aims mainly at the protein side. STABICLEAR PVPP on the other hand is effective on the polyphenol side. The combination of STABIFIX silica gel and STABICLEAR PVPP is therefore ideal. With this combination a high stability can be achieved according to purity law regulation, without excessive eliminating of either, the higher molecular protein compounds or valuable polyphenol fraction. Such careful and balanced process is ideal to achieve high stabilities while maintaining the character of the beer. STABICLEAR PVPP is tailor made for a combined application with most STABIFIX silica gels. It is easy to suspend, relatively low in dust and has superior filtration characteristics. The products can be suspended together but a suspension in separate dosing vessels gives most flexibility and can result in long term cost savings. Pre-clarified beers will boost the performance of both stabiliser types at filtration stage. Often brewers decide to apply STABICLEAR PVPP at maturation stage to make full use of the adsorptive capacity and combine STABIFIX silica gel at the same stage or later at filtration stage.
STABIFIX SILICA GEL AND PVPP IN THE RECYCLING PROCESS
In order to obtain optimum operating conditions at the recycling filter it is necessary to have a bright filtered beer, as the recycling filter is not really used for filtration, but for bringing the beer in contact with the PVPP and to regenerate the PVPP. With this process a primary protein stabilisation with STABIFIX silica gel has proven to be very effective. Reduced dosing rates of 20 to 50 g/hl of STABIFIX silica gels have to be taken into account.
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OTHER STABILISATION TECHNIQUES
Brewers have developed many effective technologies for clarification and stabilisation of beer. Stabifix is supporting brewers all over the world to operate even more efficient with all available technologies. Often there is a good reason to combine technologies to achieve highest shelf-life targets. But it is of importance to optimize each technology to minimize their quality impact on the beer. This good practice challenge is valid for all applied products, purity law or not.
Brewers have developed many effective technologies for clarification and stabilisation of beer. Stabifix is supporting brewers all over the world to operate even more efficient with all available technologies. Often there is a good reason to combine technologies to achieve highest shelf-life targets. But it is of importance to optimize each technology to minimize their quality impact on the beer. This good practice challenge is valid for all applied products, purity law or not.
USE OF PROTEOLYTIC ENZYMES
The combination of proteolytic enzymes and silica gels has proven to be very successful. It allows a significant reduction of all other stabilisers applied. This can have a positive effect on costs and allows at the same time a reduction of the enzymes dosing rate (to about 1 g/hl) which is favourable for beer taste and head retention. Certain STABIFIX silica gels are a particular good fit to proteolytic enzymes and help to boost the enzyme performance. In many such cases high shelf-life can be achieved without the need for STABICLEAR PVPP.
There are two options of application: 1. The beer is pre-stabilized at the filter with 25 to 50 g/hl of STABIFIX silica gel. The enzyme is added to the filtered beer in an aqueous solution; it could also be added together with the ascorbic acid, provided the enzyme can be dissolved in water to a clear solution. 2. We recommend the addition of the proteolytic enzyme in the storage cellar, for example during the transfer process or later and a final filtration with 25 to 50 g/hl of STABIFIX silica gel. Experience shows the advantage of this process due to a longer enzyme contact time. Also a major part of the enzyme protein is eliminated from the beer already in the maturation cellar. The remaining enzyme is then adsorbed by STABIFIX silica gel at the beer filtration step. It is possible to design the process and dosage rates in a way, so that the enzyme is nearly completely removed from the final product.
It is, however, not advisable to mix STABIFIX silica gel and enzyme in one vessel as the large fractions of the enzyme will be adsorbed, resulting in reduced enzyme and silica effectiveness on the beer.
USE OF ANTIOXYDANTS
The addition of ascorbic acid or KMS to the finished beer improves the colloidal stability and contributes considerably to flavour stability. One should note, however, that the effect of antioxidants cannot compensate for an incorrect bottling technique and that, above all, they cannot be used to compensate for an excessive oxygen pick-up. In fact, ascorbic acid prolongs shelf life even if the air content is high. However, in this case ascorbic acid creates an intensive flavour deterioration after a certain period of time.
The dosing rates generally used range between 2 and 5 g/hl. This dosage improves the effectiveness of STABIFIX stabilisers considerably. A 2 to 3 fold increase of shelf life can be achieved in relation to a stabilisations with STABIFIX silica gel alone. In some cases, STABICLEAR PVPP can be reduced.
Dissolved in water the ascorbic acid has to be added to the beer after filtration. By no means should ascorbic acid be put into the kieselguhr dosing vessel. It would dissolve iron from the kieselguhr and then transfer it into the beer. Furthermore, the reductive capacity of the ascorbic acid would be partially used up by the iron of the kieselguhr.
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NO PREMIXES SUPPLIED
Why Stabifix does not supply premixes, blends and multifunctional products?
There are three desired main functions when it comes to the task of achieving long term clarity in beer:
1. Clarification, Removal of particles
2. Protein stabilisation, Removal of haze sensitive proteins
3. Polyphenol stabilisation, Removal of haze reactive polyphenols
The Stabifix product range addresses all such functions with a focus on the stabilisation of proteins and polyphenols, leaving the final clarification to membranes or DE filters. All Stabifix stabilisers and pre-clarifiers can be used in combination with each other. Sometimes a sequential application will be beneficial.
Several suppliers to the industry offer fixed blends or modified multi-purpose products, often combining two of the three before-mentioned functions. It needs to be recognised though, that removing haze particles with filtration aids for clarification is a different technical task, than removing haze sensitive proteins, which again is a different task, than removing polyphenolic haze precursors.
Certainly most processing aids have more than one isolated effect during its application: Silica gel can contribute to a sharper filtration performance, PVPP can co-adsorb some proteins, deatomaceous earth will remove some haze precursors. But none of the products will do a complete job on all required functions. One product – a blend, premix or modified adsorber – may have dual effects, but it is impossible that both such effects will be applied at an optimised rate. One of the two will either be insufficient – with a need to be supported by an additional product – or it is overdosed, so part of the product is wasted and beer quality sacrificed by excessive adsorption of beer components.
In an ideal scenario, each of the three tasks are evaluated (measured) and addressed individually on as-needed basis. This does not mean it cannot be done in one step. But not with one product. It also needs to be considered, that raw materials and processes do change and the ratio of applied product functionality needs to be shifted.
If an assessment of a multiple function product is required, the performance of each function needs to be evaluated and – ideally – compared to the cost performance of the corresponding mono functional products.
Stabifix will offer recommendations and solutions for each individual task the brewer is faced, when it comes to clarifying and stabilising beer: removal of haze particles, removal of haze sensitive proteins, removal of haze reactive polyphenols. Each at a perfectly well set dosage rate. No insufficient nor excessive treatment. No waste of capacity or money. Follow that good principle and let Stabifix support you in finding your best mix for each beer.
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SERVICE
We, the Stabifix team, comprise of professional brewers, who are experienced in stabilisation and filtration matters. We live in the brewing industry and we are enthusiastic about what we do. We like to work closely with our customers to achieve optimum results. Brewery stabilisation audits are a part of our regular work, such as detailed laboratory investigations, process recommendations and brewery staff training. Call our team and challenge us.
GET IN TOUCH
HEADOFFICE
Stabifix Brauerei-Technik GmbH & Co. KG
Fraunhoferstraße 8
82152 Planegg / Munich
Germany
PHONE
+49 (0)89 898 999-0
FAX
+49 (0)89 898 999-79
brauereitechnik@stabifix.com
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GET IN CONTACT
HEADOFFICE
Stabifix Brauerei-Technik
GmbH & Co. KG
Fraunhoferstraße 8
82152 Planegg
Munich
Germany
PHONE +49 (0)89 898 999-0
FAX+49 (0)89 898 999-79
MAILbrauereitechnik@stabifix.com