DE102012110721A1 - Process for the fermentation of beer wort and green beer to beer - Google Patents

Abstract

The production of beer can be improved if, during the main fermentation and / or the secondary fermentation of the wort or the green beer, a pressure is generated in the head area that is lower than the ambient atmospheric pressure.

Description

Technical area

The invention relates to a method for producing beer.

State of the art

The production of beer usually comprises at least the steps of malting a cereal, producing a wort from the grain, main fermentation of the wort, which is also abbreviated as wort to a so-called young beer and a secondary fermentation of the young beer.

When malting cereal is germinated, forming enzymes that allows a split of starch contained in the grain to sugar. The malted grain is then mashed with water and a seasoning is prepared, the starch being split by the enzymes and the sugars thus obtained dissolved. In the subsequent main fermentation, the sugar is converted by yeast to alcohol and carbon dioxide (CO ₂ ). The resulting intermediate product is called a green beer. After at least a large part of the sugar has been converted into the wort, the so-called secondary fermentation of the green beer takes place, which is referred to as storage or maturation. Only with the secondary fermentation the finished beer develops. In the secondary fermentation of the yeast not only the remaining sugar, but if it is at least largely degraded and proteins and the like. Be metabolized to alcohol and CO ₂ .

At least during the secondary fermentation, the corresponding storage tank is under a so-called bunging pressure. This serves to dissolve at least part of the CO _{2 produced} in the beer, so that the finished beer has a CO ₂ content of typically 4 to 6 g / l for pils and lager beers and 5 to 8 g / l for wheat beers having. Only then the beer bubbles. Beer with a CO ₂ content of less than ₃ g / l is considered inedible and will not be accepted by the consumer.

Presentation of the invention

The invention is based on several observations: First, the main fermentation takes place today in up to 30m high fermentation tanks. As a result, the yeast has a high hydrostatic pressure, which has a negative effect on the yeast, ie the yeast metabolizes the existing sugar much slower than at lower hydrostatic pressure. On the other hand, at the latest during secondary fermentation, the pressure in the storage tank, for example by a bunging apparatus, is increased by about 0.5 to 2 bar (1000-2000 hPa) above the ambient pressure so that the desired amount of CO _{2 dissolves} in the beer. The pressure under which the secondary fermentation takes place is usually set as a function of the temperature at which the secondary fermentation takes place and the desired CO ₂ content and can be taken from pressure tables which usually indicate values between 0.5 bar and 4 bar. So that the storage tanks do not burst under pressure, they must be designed to be stable.

The invention has for its object to reduce the investment costs for the fermentation and to optimize fermentation.

This object is achieved by a method according to claim 1. Advantageous embodiments of the invention are specified in the subclaims.

The process for the production of preferably alcoholic beer has at least the steps of main fermentation of wort in a fermentation tank for producing a green beer and / or secondary fermentation of the green beer in a storage tank. Preferably, in the main fermentation in the head region of the fermentation tank, a pressure is generated which is less than the ambient pressure. The pressure may be, for example, 750 hPa or less, preferably less than 500 hPa, more preferably less than 250 hPa. The pressure should only be above the saturation vapor pressure of the wort to prevent it from boiling. This reduces the total pressure on the yeast, which is composed of the hydrostatic pressure and the air pressure in the head area of the fermentation tank. The minimum sensible air pressure in the head area is determined by the vapor pressure of the alcohol produced during fermentation. Because the yeast produces CO ₂ during fermentation, the pressure rises in the top of the fermentation tank when the resulting CO _{2 is} not removed. Therefore, at least a part of the volume of the CO _{2 produced should be} subtracted in order to keep the pressure in the head area as low as possible. The withdrawn CO ₂ is preferably collected and may optionally be stored, stored in compressed form and used, for example, for the subsequent carbonation of the beer. Then the finished beer complies with the German purity law.

If the (air) pressure in the head area of the fermentation tank is reduced eg to 100 hPa by means of a vacuum pump, then the total pressure at the bottom of a fermentation tank with a filling height of 30 m is about the same as that at the bottom of the fermentation tank with a filling height of only 21 m (at atmospheric pressure of typically on the order of 1013 hPa in the head area), thereby creating significantly improved living conditions for the yeast in the fermentor. It is therefore possible to dispense with the revitalization of the yeast, which is otherwise necessary at these fill levels, before reuse. In addition, the fermentation runs clearly faster, which increases the potential beer output. Alternatively, you could increase the filling level in the fermentation tank by about 9m, so fill the fermentation tank up to a filling height of up to 39m. This results in a smaller footprint per volume of the fermentation tank, which in particular for breweries brewing within a city results in a cost advantage or added surface increases the possible beer output.

Alternatively or additionally, the pressure in the head region of the storage tank for the secondary fermentation subsequent to the main fermentation can also be reduced, preferably to a value which is less than or equal to the ambient pressure. As a result, the necessary pressure resistance of the storage tank is reduced. This can therefore be correspondingly simpler and thus cheaper compared to a storage tank according to the prior art. In addition, the green beer in the secondary fermentation does not have to be cooled down so low because with the secondary fermentation unlike the state of the art, no solution of CO ₂ in beer is intended. The aim of secondary fermentation at ambient pressure or underpressure is to dissolve as little CO ₂ as possible in the beer, as this also often simplifies the subsequent fermentation process steps such as filtering and / or pasteurization technically and the investment costs for the necessary facilities are reduced , The CO ₂ content may be, for example, less than 3 g / l beer, preferably less than 2 g / l, more preferably less than 1 g / l beer. Beer with such a low CO ₂ content is also referred to as "depressurized" within the scope of the patent application.

Another advantage of secondary fermentation at a pressure in the head of the storage tank is less than or equal to the ambient pressure, is that if no CO ₂ should be dissolved in the beer, the cooling during the secondary fermentation can be at least reduced. This also reduces the production costs. The temperature in the secondary fermentation is only to the yeast, not to adapt to the desired CO ₂ content.

If the cooling can be reduced, the secondary fermentation takes place at a higher temperature compared to the prior art and therefore faster than in the prior art. This also leads to a further cost savings.

Only after the completion of the secondary fermentation, preferably immediately before bottling in the usual containers such as bottles, cans or barrels of the otherwise finished beer preferably by means of an inline carbonator preferably still in the brewery with CO ₂ added (carbonated), then to the Transport customers. Alternatively, the beer can be transported without pressure and carbonated at the destination. When carbonating the beer almost any desired CO ₂ content can be adjusted. It can therefore be made from the same unpressurized beer different taste or Rezenzrichtungen, however, which differ (only) by the CO ₂ content

Of course, the finished beer can take intermediate steps such as be subjected to filtering or pasteurization. Due to the fact that this too can be done "without pressure", ie before the carbonization, the technical complexity is significantly reduced.

In the context of this application, the term "beer" refers to the product after completion of secondary fermentation, even if it has not yet been carbonated. "Jungbier" is something different than beer. During the main fermentation, the wort becomes green beer. The transition is continuous. Only for the sake of simplicity, in the context of this application, the wort until the completion of the main fermentation as wort and only with onset of secondary fermentation referred to as young beer. The main fermentation and the secondary fermentation takes place in containers. Merely to allow a distinction of the containers, the vessel for the main fermentation is called "fermentation tank" and the vessel for the secondary fermentation as a "storage tank". Of course, in practice, the fermentation tank can also be the storage tank. For some breweries, however, this is not the case because of the different temperatures at which the main and secondary fermentation take place. According to the invention, the otherwise usual pumping over is no longer necessary.

The head region of a tank is usually described as the area of a tank which is provided between the liquid level and the tank lid. This area is often referred to as a "fermentation room" because it absorbs the resulting during fermentation foam. According to the invention, the fermentation tank and / or storage tank are therefore preferably closed containers, with a connection in the head region, by means of which a negative pressure can be generated by means of a vacuum source, eg a vacuum pump in the head region of the corresponding tank. Alternatively, the hydrostatic pressure can be used to generate a negative pressure in the head region of the fermentation and / or storage tank: It is sufficient to fill the corresponding liquid in the tank and close the headspace tight. Then, at the bottom of the tank, some liquid can be removed via a valve. As a result of the hydrostatic pressure of the liquid (wort, green beer, beer), a pressure which is smaller than the ambient pressure and limited either by the difference between the ambient pressure and the pressure of the liquid column in the tank or the vapor pressure of the liquid is established in the head region is. If the desired negative pressure is set in the head area, then the valve can be closed again. The withdrawn in this way liquid can in another tank be filled again and so also be fed to the fermentation. It does not have to be discarded.

Negative pressure here means a pressure in the head area which is smaller than the atmospheric ambient pressure. The ambient pressure at standard conditions is 1013hPa, but varies depending on the height of the measuring station and weather conditions. If, at the location of the main and / or secondary fermentation, an ambient pressure of e.g. 1013 hPa, then the head pressure is preferably less than 1013 hPa, e.g. 750 hPa or less, preferably less than 500 hPa, more preferably less than 250 hPa.

By adjusting the pressure in the head region of the fermentation and / or storage tank to a predetermined value, you also get a product that is less dependent on the usual pressure fluctuations. By selecting a predetermined temperature and a predetermined (sub) pressure, a green beer or a beer can be produced with a reproducibly set (low) CO ₂ content.

The pressure in the head region of the fermentation tank and / or storage tank is preferably regulated or controlled at least approximately to a constant value during the main fermentation or subsequent fermentation. However, pressure fluctuations in the fermentation tank and / or storage tank can be used to achieve an at least partial rearrangement of the young beer or the wort. For example, the pressure in the headspace can oscillate by a certain amount.

Preferably, a differential pressure between the area of the tank bottom and the head space is determined. Particularly preferably, the differential pressure is determined by at least two in a fixed known vertical distance from each other and below the expected filling level arranged pressure sensors. On the basis of this differential pressure, the progress of the fermentation, ie the degradation of the sugar contained in the wort or the green beer can be determined. From the differential pressure can be determined directly because of the known vertical distance, the density and thus the sugar content of the liquid. In addition, as a rule, the initial density of the wort is known, which allows a calibration of the measurement. Particularly preferably, the change in the differential pressure is determined as a function of time, that is, the derivative of the differential pressure. Since the main and the secondary fermentation are each carried out at at least approximately constant temperature, it can be concluded from the derivation without knowledge of the expected minimum differential pressure or the initial density on the sugar content. The hitherto necessary usually manually performed removal of a sample can then be omitted. Another advantage of the method is that the differential pressure is a measure of the average density of the liquid column in the fermentation and / or storage tank. In the manual sampling, this is usually done via a sampling tap in the lower part of the tank, the liquid in the tank is usually layered according to their density (if no complicated circulation takes place).

A beer brewed by the method described above can be analytically distinguished from a beer brewed without the pressure reduction described, because the yeast is less stressed because of lower hydrostatic pressure and lower CO ₂ partial pressure in the liquid. This low stress manifests itself in a slightly different composition of the metabolites, eg a lower diacetyl value.

Brewery for carrying out the method therefore preferably has at least one fermentation and / or storage tank, the means for generating a pressure p less than or equal to the ambient pressure in the headspace of the fermentation and / or storage tank during the main and / or secondary fermentation. The fermentation and / or storage tank is preferably cased with the brewhouse or piped to a wort reservoir. Also preferably, the fermentation and / or storage tank can be connected to a bottling plant for bottling the beer in pressure-resistant containers, the bottling plant preferably has a carbonator to the beer with the desired CO ₂ content to set (typically greater than or equal 3.5 g / l and less than 10g / l of beer). The carbonator may be, for example, an in-line carboniser. Alternatively, the carbonization can also be done in a pressure-resistant container in which the finished beer is delivered.

Of course, between the fermentation and / or storage tank, a filtering system or plant for pasteurization and / or short-term heating, as well as pumps, valves and the like can be interposed.

As a means for generating the negative pressure in the head region of the cooking and / or storage tanks, for example, vacuum pumps and / or water jet pumps and / or turbomolecular pumps are suitable. The outlet of the corresponding pump is preferably at least indirectly connected to the carbonator in order to reintroduce the CO ₂ produced by the yeast to the beer. Particularly preferably, the pump feeds a pressure reservoir from which the carbonator removes the CO ₂ .

The invention has been described with reference to beer, but it can be transferred to all previously fermented under pressure or atmospheric pressure beverages, if the fermentation produces a gas, for example CO ₂ . By lowering the pressure in the head of the fermentation tank below the ambient pressure. The alcoholic fermentation is therefore only one example of a fermentation. In some countries, the above-mentioned malting is omitted, where unmalted starch carriers are also mashed and made into a wort, the necessary enzymes being added differently or by small additions of malted starch carriers.

The core of the invention is the knowledge that the only reason for a fermentation under an overpressure in the head region of a fermentation tank is the solution or at least temporary physical binding of CO ₂ in the liquid, but that this overpressure in the head area leads to a multiplicity of problems ( so), in particular also slows down the fermentation, because CO _{2 is} a metabolite of the microorganisms used for the fermentation, such as yeasts. According to the prevailing opinion, secondary fermentation under an overpressure is the only method to bind sufficient CO ₂ in beer. By lowering the pressure level in the head region of the fermentation tank below the ambient pressure, an enrichment of the metabolic product can be reduced, if not prevented. The only supposed disadvantage that the CO ₂ must be added to the end product by the so-called carbonization is overcompensated by advantages (see above) in the handling of the unpressurised intermediates.

Description of the drawings

The invention will now be described by way of example without limitation of the general inventive idea by means of embodiments with reference to the drawings.

1 shows an apparatus for carrying out the method

The single figure shows a fermentation and storage tank 10 , with a tank wall 10 , a tank bottom 18 and a gas cap 19 , Inlet and outlet 12 , which is preferably shut off via an indicated valve can eg wort or a green beer (indicated as liquid level 20 ) in the tank 10 be filled around this in the tank 10 to ferment. Accordingly, the wort was preferably added to fermentation yeast. About the inlet and outlet 12 , preferably in the area of the tank bottom 18 can be taken from an intermediate product, such as young beer or "ready" beer.

Between the tank lid 19 and the liquid level 20 is a headspace 17 also as a fermentation room 17 referred to as. By means of a manometer 15 or a pressure sensor 15 can the pressure p in the head area 17 be measured.

A controller 40 evaluates the measured pressure p and controls a vacuum pump 30 such that the pressure p in the head space is smaller than a predetermined value p _max . The vacuum pump is preferred 30 controlled in such a way that the pressure p remains larger than a lower barrier p _min . This compensates for an increase in the pressure in the fermentation chamber due to CO ₂ liberated during fermentation without the risk that the liquid will start to boil, provided that lower limit p _{min is} greater than the saturation vapor pressure (in short "vapor pressure").

On the wall 11 the cooking and / or storage tank 10 are at a fixed vertical distance h to each other two pressure sensors p1, p2 arranged the pressure values p ₁ , p ₂ to the controller 40 transfer. The differential pressure Δp = p ₂ -p ₁ is directly proportional to the density ρ = Δp / (h · g) of the liquid column between the two pressure sensors, where g denotes the gravitational acceleration. Thus, the sugar content can be determined by means of the differential pressure measurement.

LIST OF REFERENCE NUMBERS

10

Fermentation and / or storage tank

11

wall

12

Inlet and outlet

14

Discharge opening / venting

15

Pressure gauge / pressure sensor

17

Headspace / fermentation room

18

tank bottom

19

filler cap

20

Liquid level of the wort or the green beer

30

Vacuum pump

40

control

p1

pressure sensor

p2

pressure sensor

Claims (10)

Process for the production of beer with at least the steps a. a main fermentation of a wort in a fermentation tank ( 20 ) for the production of a green beer and / or a b. Fermentation of young beer in a storage tank ( 10 ), characterized in that during the main fermentation and / or during the secondary fermentation in a headspace ( 17 ) of the fermentation tank ( 20 ) and / or the storage tank ( 20 ) a pressure (p) is set which is less than or equal to the ambient pressure. A method according to claim 1, characterized in that after fermentation, the beer is carbonated and bottled. A method according to claim 2, characterized in that the beer is filtered between the secondary fermentation and the carbonization. Method according to one of claims 1 to 3, characterized in that the pressure (p) in the headspace ( 17 ) is adjusted by the fact that at the lower end of the fermentation tank ( 10 ) and / or the storage tank ( 10 ) Wort and / or green beer is drained, without the air in the fermentation tank ( 10 ) and / or the storage tank ( 10 ) flows. Method for optimizing the monitoring of a main fermentation of wort to green beer in a fermentation tank ( 10 ) and / or secondary fermentation of a young beer in a storage tank ( 10 ), in particular according to one of the preceding claims, characterized in that a differential pressure (Δp) between at least two with a vertical distance from each other within a fermentation and / or storage tank arranged pressure sensors (p1, p2) is determined and based on the differential pressure (Δp) on the density and / or the sugar content of the wort and / or the green beer is concluded. Alcoholic beer, characterized in that it was brewed by a process according to any one of the preceding claims. Device for producing beer, in particular beer brewery for carrying out a method according to one of claims 1 to 5, characterized in that the device comprises at least one fermentation and / or storage tank ( 10 ), the means ( 30 ) for generating a pressure p less than or equal to the ambient pressure in the headspace ( 17 ) of the fermentation and / or storage tank ( 10 ) during the main and / or secondary fermentation. Apparatus according to claim 7, characterized in that the fermentation and / or storage tank ( 10 ) is connected at least indirectly with at least one bottling plant for bottling the beer in pressure-resistant container, wherein the bottling plant has a carbonator to put the previously depressurized beer with CO ₂ , so that it has a CO ₂ content greater than or equal to 3.5 g / l and less than 10g / l of beer. Use of a tank with means ( 30 ) is connected to generate a negative pressure at least in the headspace of the tank as a fermentation and / or storage tank ( 10 ) in the main and / or secondary fermentation of wort and / or green beer to preferably pressureless preferably alcoholic beer. The subject matter of one of claims 7 to 9, characterized in that the means ( 30 ) for generating a pressure p of less than the ambient pressure is a vacuum pump, preferably a vacuum pump and / or water jet pump and / or turbomolecular pump.

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