Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12H—PASTEURISATION, STERILISATION, PRESERVATION, PURIFICATION, CLARIFICATION OR AGEING OF ALCOHOLIC BEVERAGES; METHODS FOR ALTERING THE ALCOHOL CONTENT OF FERMENTED SOLUTIONS OR ALCOHOLIC BEVERAGES
  • C12H1/00—Pasteurisation, sterilisation, preservation, purification, clarification, or ageing of alcoholic beverages
  • C12H1/12—Pasteurisation, sterilisation, preservation, purification, clarification, or ageing of alcoholic beverages without precipitation
  • C12H1/16—Pasteurisation, sterilisation, preservation, purification, clarification, or ageing of alcoholic beverages without precipitation by physical means, e.g. irradiation
  • C12H1/18—Pasteurisation, sterilisation, preservation, purification, clarification, or ageing of alcoholic beverages without precipitation by physical means, e.g. irradiation by heating
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12H—PASTEURISATION, STERILISATION, PRESERVATION, PURIFICATION, CLARIFICATION OR AGEING OF ALCOHOLIC BEVERAGES; METHODS FOR ALTERING THE ALCOHOL CONTENT OF FERMENTED SOLUTIONS OR ALCOHOLIC BEVERAGES
  • C12H6/00—Methods for increasing the alcohol content of fermented solutions or alcoholic beverages
  • C12H6/04—Methods for increasing the alcohol content of fermented solutions or alcoholic beverages by freezing

Definitions

• the present invention relates to the preparation of beer of the "Pilsener” or “lager” type having an alcohol content of 3.5 to 6.5 % by volume, wherein wort is brewed starting from malt, and wherein this wort is boiled and supplemented with hop and/or a hop extract and fermented after cooling.
• Pilsener beer a light beer is meant having an alcohol content as already set forth hereinabove which may vary between 3.5 and 6.5 % by volume and the taste of which is determined to a large extent a.o. by the used hop or hop extracts. It is thus a pale, weekly hopped beer which is usually of bottom fermentation.
• the different raw materials including water, malted barley, hop and yeast and further the relative amounts thereof are chosen such as to obtain a certain taste pattern and this within a certain type of beer, in this case a Pilsener beer.
• the manufacturers of the different Pilsener beers strive for brewing a well balanced beer which take the fancy of a certain public.
• the properties which are considered in this respect include amongst others the palate-fullness, the aftertaste, the aroma and the alcohol content.
• these properties are mainly determined by the used raw materials, the mutual ratio's thereof and by the manufacturing and conditioning process.
• An object of the invention is now however to propose a new process which enables to influence the taste of the beer in another way and which enables more particularly to give the beer a more powerful, fresher flavour and a stronger aroma.
• the process according to the present invention is characterised to this end in that the fermented wort is subjected to a freeze concentration step wherein 5 to 15 % of the fermented wort is removed in the form of ice from the thus obtained beer.
• the process according to the invention involves the important difference that the freeze concentration step does indeed influence the alcohol content, the flavour and the aroma of the beer without substantially changing however the beer density. In is in other words a same light beer with a more powerful taste, a stronger aroma and a somewhat higher alcohol content.
• hop extract of a hop extract from which bitter substances present therein have been extracted.
• the flavour and in particular the aroma of the beer can be reinforced by the freeze concentration step without rendering the beer too bitter.
• the beta-fraction is maintained whereas the alpha-fraction is mainly discarted. In this case, it is more particularly a so-called "aroma hop".
• said freeze concentration step is performed in a tank, in particular in the tank wherein the wort has been fermented previously.
• Another advantage thereof is that no beer transport is required since the entire process can be done in one tank, which enhances the flavour stability and reduces the risk of a possible oxidation.
• wort is produced from the malt by grinding the malt and brewing it at certain temperatures.
• the obtained wort is then boiled and supplemented during this boiling with a hop and/or a hop extract.
• this wort can then be fermented by means of yeast whereby the sugars present therein are converted into alcohol.
• the hop is mainly applied for its bitter acids, in particular humulon, which is converted during boiling to the soluble isohumulon Further it is applied for its volatile hop oils These oils are mainly lost during boiling but the remaining small amount improves the aroma of the beer
• the fermentation process also provides the flavour of the beer Indeed, during this process there is not only production of alcohol and carbon dioxide, but also a little glycerol, higher alcohols and esters which make the beer pleasant to taste
• the process according to the invention includes a freeze concentration step applied after the fermentation process In this freeze concentration step, 5 to 15 % of the fermented wort is discarted in the form of ice It has been found that the flavour and the aroma of the beer can be reinforced considerably in this way without a substantial change in beer density The beer remains in other words a light Pilsener beer having however, a somewhat higher alcohol content
• a far too high bitter content is not desired in practice since this could influence the aroma obtained by the alcohols esters and higher alcohols
• the freeze concentration step can be carried out either according to a flow-through process or according to a discontinuous batch process. Devices for carrying out a flow-through freeze process are already known per se, for example from Canadian patent No. 601.487.
• the annexed figure shows an example of a fermentation tank which has been adapted for carrying out the freeze concentration step.
• a number of cooling circuits 2 are applied around the fermentation tank 1 which is known per se.
• a cooling fluid for example ammonia, is supplied in liquid form through supply ducts 3 into the cooling circuits 2 and removed, after evaporation in these circuits 2, through discharge ducts 4.
• the chain is then closed by a not shown compressor which transforms the discharged cooling gas back into liquid cooling liquid.
• the fermentation tank 1 is further provided with an insulation casing 5 which has only been shown partially.
• the illustrated fermentation tank 1 comprises, moreover, at the top an under-pressure relieve valve 10, a pressure relieve valve 11 and a CIP (cleaning in place) spray nozzle 12 connected to a supply duct 13 for the cleaning liquid. Since these are however known elements which do not belong to the essence of the invention, they will not be discussed here into detail.
• the fermentation tank 1 is connected at the bottom through a valve 6 to a supply and discharge duct 7. Through this duct 7 the cooled wort is supplied into the tank 1 wherein, after pitching with yeast, the fermentation takes subsequently place. After the fermentation, the yeast is collected as much as possible since a long time of contact between the yeast and the beer could have a negative influence on the flavour stability. After having removed the yeast, the fermented wort or in other words the beer is cooled by means of the cooling circuits 2 down to below its freezing point.
• this cooling process is a slow process taking in particular a period of 50 to 120 hours, and preferably a period of 72 to 96 hours, and this for the usual fermentation tanks having a total volume of about 500 hi. Due to this cooling down process, an ice layer 8 will be deposited on the wall of the tank 1.
• an inert gas is preferably injected at the bottom in the beer to achieve in this way a homogeneous cooling.
• the beer is prevented hereby from freezing up into one block of ice.
• the gas is injected by means of an injection system 9 which debouches substantially in the middle of the tank, thus reinforcing the convection currents in the beer.
• use is made as inert gas, in a first phase, of nitrogen gas whereas, in a second phase, use can be made of carbon dioxide.
• the use of CO 2 gas is preferably stopped to avoid unnecessary stripping of aroma components from the beer.
• the beer is preferably cooled down to 0.5 to 1.5°C below its initial freezing point, in particular to for example 1 °C below its initial freezing point. It has been found that at such supercooling temperatures, a good flavour could be obtained.
• the somewhat concentrated beer is discharged from the fermentation tank 1 through the duct 7. Subsequently, the ice 8 in the tank 1 is molten and the resulting liquid is also discharged from the tank 1 through the duct 7. In this phase, the amount in percentage of ice is easy to determine.
• the amount of ice could also be determined directly. However, it is easier to follow the evolution of the amount of ice based on the alcohol content. Indeed, the increase in percentage of the alcohol content corresponds to the increase in percentage of the amount of ice with respect to the total amount of beer.
• Pilsener beer having an alcohol content of 5.3 % by volume was brewed in the usual way.
• a hop extract was added, more particularly hop in a CO 2 extract form out of which the alpha-fraction has been removed. It was more particularly a so-called aroma hop with 65 to 70 % beta-fraction, less than 0.2 % alpha-fraction, 15 to 20 % hop oils and the remaining percentage water. 1.2 kg of this extract were added per 300 hi wort.
• the boiled wort was subsequently cooled down to 11.1°C, pitched with yeast (Saccharomyces carlbergensis) and pumped in the cylindro-conical fermentation tank 1 having a total volume of 5000 hi until this tank was filled for about 80 %.
• yeast Sacharomyces carlbergensis
• the temperature rose in about 60 hours to 15.5°C.
• the entire fermentation took about 8 days followed by 14 days maturation (ripening). Fermentation ended by end-fermentation of the wort, in particular of the sugars contained therein. Two degrees plato before end-fermentation, the yeast which was deposited on the bottom of the tank was collected and removed.
• the so-obtained beer had an alcohol content of about 5.3 % by volume and a freezing point of -2.81 °C.
• the beer was cooled down in about 3 to 4 days to a temperature of -3.8°C.
• nitrogen gas was injected, in a first phase, for up to 72 hours at the most at the bottom in the beer at a flow rate of 1.19 kg N 2 per hour.
• CO 2 gas was injected until the CO 2 content of the beer was about 6 g per I.
• the evolution of the alcohol content was followed by measuring this content periodically.
• the freeze concentration step was ended.
• the concentrated beer was filtered on a kiezelguhr filter and subsequently on a plate filter.
• the ice layer deposited on the wall of the fermentation tank was removed.
• freeze concentration step does not necessarily have to take place in the fermentation tank but that it is possible to provide hereto a separate tank or a separate flow-through system..

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• Chemical & Material Sciences (AREA)
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• Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)

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Cited By (4)

Citations (6)

• 1996
  • 1996-04-04 BE BE9600285A patent/BE1010114A5/nl not_active IP Right Cessation
• 1997
  • 1997-04-04 WO PCT/BE1997/000042 patent/WO1997038081A1/en active Application Filing

Patent Citations (6)

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