GB2294944A

GB2294944A - Stabilising beer by removal of haze precursors

Info

Publication number: GB2294944A
Application number: GB9521911A
Authority: GB
Inventors: Robert Preston Besford; David John Lummis
Original assignee: Bass PLC
Current assignee: Bass PLC
Priority date: 1994-11-09
Filing date: 1995-10-26
Publication date: 1996-05-15
Anticipated expiration: 2015-10-26
Also published as: GB9521911D0; WO1997043400A1; GB2294944B

Abstract

Beer, particularly green beer, and like beverages are stabilised by the addition thereto of an agent or material which reacts with a haze precursor and causes it to precipitate out. The material may be a tannin or tannin-like material, a phenol or polyphenol, a silica hydrogel or an activated clay and may be added to beer which is flowing from a fermentation vessel to a filter. Apparatus 12 for the flash stabilisation of beer from such a vessel 11 may comprise a heat exchanger 16 to chill the beer, an agent-introducing system 18 and a centrifuge 20, a filter 14 being provided to remove remaining particulates.

Description

IMPROVEMENTS IN AND RELATING TO PRODUCTION OF BEVERAGES This invention relates to the production of beverages. It is particularly, but not exclusively, concerned with brewing. It may be applicable to the production of beer, ale, lager, stout, cider, wine or the like.

In brewing, beer is produced in a fermentation vessel. Such beer, termed green beer, has been fermented but contains particulates, yeast and other materials not desirable in the finished product. Green beer also contains proteins and polyphenols which are in solution. Unless it is prevented these chemicals may eventually precipitate out of solution and create a haze in the beer. Hazy or cloudy beer is not attractive to consumers of the product.

Once the step of fermentation is complete, the green beer is removed from the fermentation vessel and pumped into a maturation tank. During transfer, additions can be made to the green beer. Additions can include beer which has been recovered from other process steps (known as recovered beer) and materials (known as finings) that react with and precipitate particulates such as yeast and proteins.

A maturation or "conditioning" step is carried out in the maturation tank. The contents of the tank are kept for some time at a low temperature, for example 2-3 days at -1 to -20C. During this time, proteins and, arguably, polyphenols precipitate out and provide the resultant beer with better colloidal or haze stability. This means that the resultant beer will have long term clarity. The maturation step also allows other materials in the beer, for example yeast and particulates, to settle out of the beer.

Following maturation, the beer is passed through a filter to remove any particulates still in suspension, may be diluted to bring its alcohol content to the required level, and may be placed in a bright beer tank prior to packaging.

Maturation/stabilisation is a very traditional step which has been used in the production of beer for hundreds of years. Historically, in the UK, during maturation the beer was maintained at a warm temperature and this step was thought to serve the purpose of a flavour stabilising step, also as well as improving the brightness, or clarity, of the beer.

Later it became preferred to achieve the desired flavour in the fermenting vessel and to achieve colloidal stability at a lower temperature solely to precipitate haze promoting materials in the beer.

Maturation is a buffer stage in the production of beer between the relatively continuous steps of beer fermentation and beer packaging. It represents a bottleneck in the continuous production of beer. It is a batch process which is inefficient and slow. The apparatus associated with maturation adds further to the complexity and cost of apparatus of the brewing process. The costs of the maturation stage are large.

Furthermore, since maturation is a batch process each maturation tank has to be cleaned of the precipitate and settled materials therein and these materials, in large amounts, have to be disposed of. In an environmentally conscious world, the disposal of large, bulk, quantities of waste from a brewery is of concern.

However, a beer must be stabilised in order to prevent haze.

It is an aim of the present invention to alleviate at least some of the problems discussed above.

According to a first aspect of the invention we provide a method of stabilising green beer, in which the step of stabilising the beer is not the traditional step of leaving the green beer to stand in a maturation tank for a period of the order of days, but instead comprises treating the green beer with an agent which reacts with one or more of the haze precursor substances present in green beer (which would otherwise cause the formation of a haze in the beer during its shelf-life) so as to precipitate out said precursor substance.

Preferably the precipitate is separated from the stabilised beer.

Thus the green beer is matured by the operation of a precipitating or complexing agent. This enables the green beer to be stabilised very quickly indeed (in one embodiment, in a matter of minutes, and in another embodiment a matter of hours, rather than days). This reduces a bottleneck in the production of beer, and reduces the need to tie up maturation capacity.

Each maturation tank can cost ìm or so, and a large brewing may have 50 or so maturation tanks.

Indeed, looked at in one way the essence of this invention is the realisation that the long stage of maturing beer in maturation tanks is not essential after all, and that we can flash-stabilise the beer in a very short time. The place in the process at which the agent is added in one embodiment is also worth noting - after fermentation , but not in a conditioning tank in the old way.

Preferably the agent reacts with protein haze precursor substances in the green beer produced by fermentation.

Preferably the agent is a tannin, tannin acid, tannin salt, or tannin-like material.

Preferably the green beer is chilled during the stabilising step. The green beer may be chilled before, during, or after the addition of the agent.

Preferably the green beer is, after the agent has been added, coarse filtered so as to remove at least a substantial part of the precipitated material. The coarse filtering may be achieved by a centrifugal process or by a through-flow filter. The beer is preferably fine filtered after it has been coarse filtered.

According to a second aspect of the invention we provide a method of stabilising beer comprising the step of adding an agent or material to the beer which reacts with a haze precursor in the beer.

Preferably the agent or material is added in sufficient amount to flash-stabilise the beer.

Preferably the beer is green beer.

The agent may react with more than one haze precursor. More than one agent may be used.

The agent may be a phenol or a polyphenol.

Preferably the agent is a tannin-like material.

The tannin-like material may be a gallotannin.

Preferably the agent is a tannic acid. Most preferably the agent is Brewtan (trademark). The Brewtan may be Brewtan C or Tanal SC. Brewtan is a tannin-like polyphenol.

Alternatively the agent may be a silica hydrogel or an activated clay, for example bentonite.

Preferably the method is applied to beer which is flowing. Preferably the beer is flowing through a conduit. Preferably the beer is flowing from a fermentation vessel to a filter.

Alternatively we believe that we could conceivably flash-mature/stabilise the beer at other locations in the production process, for example in the fermenting vessel (for example by adding an agent to the fermentation vessel).

The method may comprise a cooling step to be performed on the beer. Cooling means may act upon the beer. Preferably the cooling means is an in-line heat exchanger.

The cooling step may occur before the tannin-like agent is added to the beer.

The beer may be cooled to a temperature in the range of -60C to 250C, and most preferably in the range of OOC + 50C. Preferably the beer is cooled to a temperature within the range -20C to 20C. Most preferably the beer is cooled to a temperature substantially in the range -20C to OOC, and most preferably to about -10C.

Preferably flash-stabilising means is provided which includes material removal means. The material removal means may be a centrifuge.

Preferably the beer is cooled for a period of time substantially in the range 30 to 300 seconds.

Preferably the period of time is substantially in the range 30 to 100 seconds. Most preferably the period of time is approximately 1 minute.

If we chose to flash-stabilise directly in the fermentation vessel we may not cool at all, and if we did cool we might cool for much longer (for example something of the order of 1 to 12 hours).

The method may comprise a solids or particulates materials removal step. Material removal means may be provided for example centrifuge means and/or filter means. The materials removal step preferably occurs after the tannin-like agent (or other agent) is added to the beer.

The beer is preferably clarified a short time after the agent or material has been added. (For example 10 seconds, or 30 seconds, or 60 seconds, or 90 seconds, or 120 seconds, or 180 seconds or 240 seconds or 300 seconds or 1000 seconds or longer, after addition of the agent or material.) The beer may be filtered at any time within ranges of time defined by any combination of the aforementioned times.

Alternatively, if the beer is matured in the fermentation vessel it may not be filtered for some time after the agent has been added - for example not for 1 hour, or 2 hours, or even up to 12 hours or so.

In the beer, the tannin-like agent (or other agent) may encourage the formation of chemical complexes incorporating haze precursors or haze forming agents to precipitate them out of solution. Addition of further tannin-like agent may shift the equilibrium of the reaction from haze precursors or haze forming agents to complexes incorporating these materials such that more complexes are produced.

Beer has tannins (polyphenols) in it naturally.

Adding substances such as exogenous tannins, shifts the balance of the equilibrium reaction of haze formation and accelerates the process, allowing the precipitated material to be removed, and reducing the capacity of the filtered beer to haze in the future.

We prefer to remove protein haze precursors from the beer in preference to polyphenolic materials.

Polyphenolic materials are believed to contribute to the taste of beer. However, in some circumstances we may choose to remove polyphenolic haze precursors from the beer.

According to a third aspect of the invention we provide maturation means adapted to flash-stabilising beer comprising means adapted to add an agent to the beer to react with haze precursors or haze forming agents in the beer.

Preferably the maturation means comprises injection means. The injection means may be adapted to add the agent to the beer. Preferably the injection means continuously, or substantially continuously, adds the agent to the beer. Instead of injecting the agent we may add it to the beer in the fermentation vessel.

We may spray it onto the top of the beer in the fermentation vessel.

Mixing means may be provided to mix the beer following addition of the agent. The agent may be added to the beer in a conduit or pipe.

Preferably the maturation means comprises cooling means. The cooling means may be a heat exchanger. The cooling means may cool the beer.

The invention may be considered to be rapidly stabilising beer without using a maturation tank.

Stabilisation may occur as the beer is being transferred from the fermentation vessel to the filtration means prior to being held in a bright beer tank.

According to a fourth aspect of the invention we provide a method of stabilising beer which is carried out on beer flowing substantially continuously from a first process step to a second process step.

Preferably the first process step is fermentation. Preferably the second process step is filtration. The second process step may be placing the beer in a bright beer tank.

Preferably maturation comprises the addition of an agent or material which may react with haze precursors and/or haze forming agents in the beer. Preferably the process also comprises chilling the beer. The process may comprise removing material, for example particulates, from the beer.

We may stabilise at a temperature between - 60C and + 250C Preferably conditioning occurs at a temperature around OOC. It may be substantially at -2, -1, 0, 1, or 20C. Preferably the beer is chilled for less than 5 minutes. It may be chilled for a stabilisation time of substantially 1 minute. If the beer is flowing from the fermentation vessel to filtration means, the distance between the fermentation vessel and the filtration means is arranged to be such that at the particular flow rate of the beer, the beer takes the necessary stabilising time to travel the distance. For example if the beer is travelling along a conduit, the path length of the conduit may be increased. The conduit path may be made tortuous or so as to wind back upon itself in order to provide a suitable distance in a relatively small volume. Preferably the system mixes the beer/agent well.The flow is preferably turbulent, at least at some point in the flow path following addition of the agent. We would aim to avoid stratification of the flow of beer.

According to a fifth aspect of the invention we provide a method of treatment of beer from a fermentation vessel such that the beer is substantially stable a short time after fermentation.

Preferably the beer is stable with respect to maintaining clarity.

Preferably the treatment of beer may comprise the addition of an agent or material which reacts with haze precursors or haze forming agents in the beer.

Preferably the treatment of beer comprises a cooling step. Preferably the treatment of beer may comprise a material removal step.

Preferably the treatment of beer comprises a mixing step.

Preferably the beer is stable substantially within 1, 2, 3, 4 or 5 minutes of the release of the beer from the fermentation tank (or the introduction of the beer to flash-stabilising means).

Alternatively, if we chose to apply an agent directly in the fermentation vessel we may need to wait up to 12 hours or so before the beer is stable.

According to a sixth aspect of the invention we provide a method of reducing the process time for stabilising beer comprising the step of adding an agent or material to the beer which is adapted to react with haze precursors or haze forming agents in the beer.

According to a seventh aspect the invention comprises the use of tannin or tannin-like material added to green beer for stabilising the beer.

Stabilising the beer is with respect to maintaining beer clarity.

According to an eighth aspect of the invention we provide apparatus for producing beer comprising a fermentation vessel; stabilising means; and filtration means; the stabilising means comprising flash stabilising means adapted to cause green beer to be brought into contact with a precipitating agent which in use precipitates out from the green beer a haze precursor so as to produce beer which substantially lacks, in solution, the haze precursor, the treated beer being filtered by the filtration means so as to separate the precipitate from the beer, thereby producing a beer which has acceptable haze stability.

According to a ninth aspect of the invention we provide a method of stabilising beer comprising stabilising the beer in the fermentation vessel in which it is brewed.

According to a tenth aspect of the invention we provide beer produced by a method which uses any of the foregoing aspects of the invention, or by apparatus in accordance with any previous aspect of the invention.

The amount of material added to the beer to stabilise it, be that material tannin-like, silica hydrogel or activated clay, for example bentonite, can be altered to produce a tailored shelf life. The amount can be such as to provide a six week life which would be suitable for keg beer, and slightly more material would be added to the beer for small pack beers or more material for export beers (which have a longer shelf-like and can effectively stabilise to a degree whilst they are waiting to be used). The amount of material added will also affect the speed of the flash-stabilisation reaction. As an example of a concentration which may be used 5g of tannin added to 100 litres of green beer with a contact time of 1 minute at a temperature of OOC will achieve good colloidal stability.

It will be appreciated that the term "beer" is intended to cover beer, lager, ale, porter, cider, and the like, and to cover low-alcohol and non-alcoholic brewed beverages.

It will be appreciated that the agent or material added should not have a substantial deleterious effect on the beer finally produced. Gallotannins are attractive to us in this regard because we have conducted tests with these and found, as yet, no deleterious effect. For example beer foam stability, and lacing, and brightness of the beer are not substantially adversely effected by a suitable gallotannin.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a traditional system for maturing beer; and Figure 2 shows a system according to the invention for flash-stabilising beer.

Figure 1 shows a system 2 for conditioning beer according to the prior art. Beer is produced in a fermentation vessel 4. Once a fermentation step is complete, beer is pumped into a maturation tank 6 where it is stored for several days at a low temperature (for example 2-3 days at -10C).

During storage in the maturation tank 6, haze precursors precipitate out of solution and settle to the bottom of the tank 6 together with other particulates and yeast. At the end of maturisation, or "conditioning", the beer is pumped through a filter 8 to remove fine particulates which are still in suspension. The beer is then diluted to produce the correct gravity of beer and the diluted beer is pumped into a bright beer tank 9 prior to packaging.

Figure 2 shows a system 10 according to the invention. Beer is produced in a fermentation vessel 11. Following the fermentation step the beer is pumped through a flash-stabilising apparatus 12 which acts on a continuous flow of beer flowing between the fermentation vessel 11 and a filter 14.

The stabilising apparatus comprises an in-line heat exchanger 16, an agent-introducing system 18 for introducing material into the beer and a centrifuge 20 for removing particulate material.

Beer which passes through the in-line chiller 16, is chilled to a temperature of around OOC, say -10C or OOC. The introduction system 18 continuously adds tannin-like material to the beer, for example Brewtan C or Tanal SC manufactured by Omnichem. Brewtan is added at a concentration of between 1 g/hectilitre and 5 g/hectilitre and it has been found that the finished beer produced still has acceptable quality. For example its foam stability, its colour, and its lacing are all still acceptable.

At the low temperature of the beer, protein haze precursors form complexes with the tannin-like material and precipitate out of solution. Polyphenols in the beer are not encouraged to precipitate out.

Polyphenols may add to the taste of beer and removal of polyphenols can be detrimental to the taste.

Mixing means is provided in the system 18 to ensure that the tannin-like material mixes with the beer. We want to achieve turbulent beer, rather than laminar flow, at least at some point to ensure good mixing. This mixing means may comprise an impeller The beer now contains particulates in suspension and also including haze precursor complexes in solution, and yeast. The beer is spun in a centrifuge 20 to encourage settling of particulates so that they may be removed from the beer.

The flash-stabilising apparatus 12 acts on beer flowing continuously through it and flash-conditions the beer. The process takes approximately 1 minute.

Since the beer is flowing, a holding tube of sufficient length is provided to provide sufficient holding time of the beer. The holding tube may be of a winding configuration which may double back on itself. By providing such a configuration, the holding tube may occupy a relatively small space.

The filter 14 is present to remove any particulates which remain in the beer following the centrifuge 20.

Beer is pumped through the filter and into a high gravity bright beer tank 22. This serves as a buffer tank before the beer is diluted and sent to a lower gravity bright beer tank 24 prior to packaging.

Alternatively the beer may not go to the tank 24, but instead may go direct to a packaging line.

The apparatus and methods according to the invention do not require maturation tanks. The very high costs associated with maturation tanks and the process of maturing in such tanks are also relieved.

The process time relates to the time required for beer to flow continuously through a stabilising system, and in one embodiment replaces a batch process with what can be a continuous process.

The invention provides a stabilising method and apparatus which is very quick and efficient compared to the prior art.

In a second embodiment we ferment beer in a fermentation vessel and then add an agent (eg Brewtan) to the fermented beer whilst it is in the vessel, precipitation and stabilisation of the beer occurring in the fermentation vessel.

In a third embodiment we may have the agent present in the fermentation vessel before fermentation starts, or at least before fermentation is completed.

Claims

1. A method of stabilising green beer, in which the step of stabilising the beer is not the traditional step of leaving the green beer to stand in a maturation tank for a period of the order of days, but instead comprises treating the green beer with an agent which reacts with one or more of the haze precursor substances present in green beer (which would otherwise cause the formation of a haze in the beer during its shelf-life) so as to precipitate out said precursor substance.

2. A method according to claim 1 which further comprises separating out the precipitate from the stabilised beer.

3. A method according to claim 1 or claim 2 which enables the green beer to be stabilised in a matter of minutes or hours, rather than days.

4. A method according to any preceding claim in which the agent reacts with protein haze precursor substances in the green beer produced by fermentation.

5. A method according to any preceding claim in which the agent added is a tannin, tannin acid, tannin salt, or tannin-like material.

6. A method according to any preceding claim in which the green beer is chilled during the stabilising step.

7. A method according to any preceding claim in which the green beer is, after the agent has been added, coarse filtered so as to remove at least a substantial part of the precipitated material.

8. A method according to claim 7 in which the coarse filtering is achieved by a centrifugal process or by a through-flow filter.

9. A method according to claim 8 or claim 9 in which the beer is fine filtered after it has been coarse filtered.

10. A method of stabilising beer comprising the step of adding an agent or material to the beer which reacts with a haze precursor in the beer.

11. A method according to any preceding claim in which the agent or material is added in sufficient amount of flash-stabilise the beer.

12. A method according to any preceding claim in which the agent may react with more than one haze precursor.

13. A method according to any preceding claim in which more than one agent is used.

14. A method according to any preceding claim in which the agent is a phenol or a polyphenol.

15. A method according to any preceding claim in which the agent is a silica hydrogel or an activated clay.

16. A method according to any preceding claim that is applied to beer which is flowing.

17. A method according to claim 16 in which the beer is flowing from a fermentation vessel to a filter.

18. A method according to any preceding claim in which the beer is cooled to a temperature in the range of OOC + 50C, and most preferably to about -10C.

19. A method according to any preceding claim in which the beer is cooled for a time in the range 30 to 300 second, and most preferably for approximately 1 minute.

20. A method according to any preceding claim which comprises filtering or centrifuging solids or particulates from the bar.

21. A method of stabilising green beer substantially as described herein.

22. Maturation apparatus adapted to flash-stabilising beer comprising means adapted to add an agent to the beer to react with haze precursors or haze forming agents in the beer.

23. Maturation apparatus according to claim 22 which comprises injection means.

24. Maturation apparatus according to claim 23 in which the injection means continuously, or substantially continuously, adds the agent to the beer.

25. Maturation apparatus according to any one of claims 21 to 24 in which mixing means is provided to mix the beer following addition of the agent.

26. Maturation apparatus according to any one of claims 21 to 25 which also comprises cooling means.

27. Apparatus for producing beer comprising a fermentation vessel; stabilising means; and filtration means; the stabilising means comprising flash stabilising means adapted to cause green beer to be brought into contact with a precipitating agent which in use precipitates out from the green beer a haze precursor so as to produce beer which substantially lacks, in solution, the haze precursor, the treated beer being filtered by the filtration means so as to separate the precipitate from the beer, thereby producing a beer which has acceptable haze stability.

28. Apparatus for stabilising beer substantially as herein described.

29. Beer produced by a method in accordance with any one of claims 1 to 21, or which uses any of the, or by apparatus in accordance with any one of claims 21 to 28.