CA2228908C - Distillation method - Google Patents
Distillation method Download PDFInfo
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- CA2228908C CA2228908C CA2228908A CA2228908A CA2228908C CA 2228908 C CA2228908 C CA 2228908C CA 2228908 A CA2228908 A CA 2228908A CA 2228908 A CA2228908 A CA 2228908A CA 2228908 C CA2228908 C CA 2228908C
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- fusel oil
- distillation
- alcoholic
- fraction
- alcohol
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- 238000004821 distillation Methods 0.000 title claims description 59
- 238000000034 method Methods 0.000 title claims description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 92
- 239000001760 fusel oil Substances 0.000 claims abstract description 58
- 230000001476 alcoholic effect Effects 0.000 claims abstract description 43
- 238000000926 separation method Methods 0.000 claims abstract description 16
- 239000012223 aqueous fraction Substances 0.000 claims description 26
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 235000013522 vodka Nutrition 0.000 claims description 9
- 235000013334 alcoholic beverage Nutrition 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 6
- 238000002194 freeze distillation Methods 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 230000000694 effects Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 abstract description 11
- 239000012071 phase Substances 0.000 abstract description 9
- 239000008346 aqueous phase Substances 0.000 abstract description 8
- 239000000243 solution Substances 0.000 abstract description 7
- 239000002609 medium Substances 0.000 abstract description 6
- 150000001298 alcohols Chemical class 0.000 abstract description 5
- 238000003113 dilution method Methods 0.000 abstract description 5
- 125000004432 carbon atom Chemical group C* 0.000 abstract description 4
- 239000012736 aqueous medium Substances 0.000 abstract description 2
- 230000000504 effect on taste Effects 0.000 abstract description 2
- 235000019441 ethanol Nutrition 0.000 description 46
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 6
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 5
- 235000013405 beer Nutrition 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 235000013339 cereals Nutrition 0.000 description 4
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 4
- QPRQEDXDYOZYLA-UHFFFAOYSA-N 2-methylbutan-1-ol Chemical compound CCC(C)CO QPRQEDXDYOZYLA-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000000855 fermentation Methods 0.000 description 3
- 230000004151 fermentation Effects 0.000 description 3
- PHTQWCKDNZKARW-UHFFFAOYSA-N isoamylol Chemical compound CC(C)CCO PHTQWCKDNZKARW-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 241000209140 Triticum Species 0.000 description 2
- 235000021307 Triticum Nutrition 0.000 description 2
- 235000020051 akvavit Nutrition 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000000796 flavoring agent Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- 240000004808 Saccharomyces cerevisiae Species 0.000 description 1
- 244000061456 Solanum tuberosum Species 0.000 description 1
- 235000002595 Solanum tuberosum Nutrition 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 125000003158 alcohol group Chemical group 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 235000019634 flavors Nutrition 0.000 description 1
- 235000013312 flour Nutrition 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 235000013531 gin Nutrition 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 235000021577 malt beverage Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- 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
- C12H6/02—Methods for increasing the alcohol content of fermented solutions or alcoholic beverages by distillation
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Food Science & Technology (AREA)
- Biochemistry (AREA)
- Bioinformatics & Cheminformatics (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Genetics & Genomics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Zoology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)
- Alcoholic Beverages (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
A fusel oil is an alcohol or a mixture of alcohols having more than two, typically four or more, carbon atoms, whose presence in alcoholic solutions may be undesirable on account of its characteristic effect on taste and/or aroma. By reducing the temperature of alcoholic aqueous media containing fusel oil, the solubility of the fusel oil in the solution may be reduced, to the point where it no longer remains in solution. The fusel oil being lighter than aqueous alcohol, the medium separates into two phases, and the fusel oil phase may be removed. A better separation of fusel oil from the alcoholic aqueous phase is thus obtained than is possible through conventional dilution processes.
Description
Distillation Method The present invention relates to a distillation method.
When producing ethanol by fermentation, alcohols with more than two carbon atoms.
such as 2-Methyl-1-Propanol. 3-Methyl-l-Butanol and 2-Methyl-l-Butanol are formed during the fermentation process. Within the fermentation industry these alcohols are generally known as fusel oil.
Fuse] oil imparts an characteristic odour and taste to ethanol and is therefore traditionally removed therefrom during the distillation process. The removal of fusel oil from distilled ethanol has hitherto taken place by removing a fusel oil-containing fraction from the distillation column where the liquid phase has an alcoholic strength of 40-50% v/v. At this strength the fusel oil, which is soluble in ethanol but less soluble in aqueous mixtures, is kept dissolved in the eyhanol/water mixture.
In order to remove it, it has been necessary to add 11/,-2 volumes of water to the fraction in order to separate the fusel oil from the alcohol by rendering it insoluble in the ethanol/water mixture. Having a lower density, the fusel oil rises to the surface of the separation vat from where it can be drawn off, while the diluted ethanol/water mixture can be recycled to the distillation column.
There are several disadvantages associated with this system. For example, the continuous addition of water to the distillation process requires the input of additional energy in order to maintain a sufficient distillation temperature in the distillation column. An increase in the volume of waste water present in the bottom of the column will also occur, which can lead to capacity restrictions. Moreover, impurities in the added water may be deposited on the walls of the distillation column, which accordingly requires more frequent cleaning.
International Patent Application W094/21779 (Labatt Brewing Company Limited) describes a process for brewing fermented malt beverages, typically beer, in which a freezing step is used in order to cause ice crystal formation in the beer. The object of this process is to prevent "chill haze" and other problems normally associated with beer. Due to the formation of ice crystals during the chilling process. beers produced by such methods are often referred to as "Ice" beers. The process effectively allows the removal of water from the brew but is not suitable for removal of fuse]
oil.
The present invention overcomes the problems of the prior art by providing a method for preparing a distilled alcohol or a distilled alcoholic beverage which comprises the removal of fusel oil contaminants at a reduced temperature.
According to a first aspect of the present invention, there is provided a process for removing fusel oil from an aqueous alcoholic medium, comprising the steps of:
(a) cooling the medium to effect separation of fusel oil from the medium; and (b) removing at least part of the fusel oil from the medium.
A fusel oil. as referred to herein, is an alcohol or mixture of alcohols having more than two, typically four or more, carbon atoms, whose presence in alcoholic solutions may be undesirable on account of its characteristic effect on taste and/or aroma. By reducing the temperature of alcoholic aqueous media containing fusel oil, the solubility of the fusel oil in the solution may be reduced, to the point where it no longer remains in solution. The fusel oil being lighter than aqueous alcohol, the medium separates into two phases, and the fusel oil phase may be removed. A
better separation of fusel oil from the alcoholic aqueous phase is thus obtained than is possible through conventional dilution processes.
Agricultural alcohol is produced by distillation of a variety of raw materials from agricultural sources, for example potato and grain. This spirit is the basis of a variety of alcoholic beverages, such as bitters, aquavit, gin and vodka. The production of, for example, aquavit, may require a second distillation step, and have flavouring substances added thereto, while others, such as vodka, may be subjected to only a single distillation, and possibly also a filtration step.
As used herein. "Agricultural alcohol-, "ethanol" and "spirit drink". as well as "vodka" and the snecific names of other alcoholic beverages, are as defined in EC
Directive 1576/89 of 29th May 1989, incorporated herein by reference.
"Ethanol" is synonymous with "ethyl alcohol", and "agricultural alcohol" is synonymous with "agricultural ethyl alcohol".
The removal of fusel oil according to the present invention is carried out during the distillation. An alcoholic aqueous fraction containing fusel oil is removed from the distillation apparatus, which is typically a distillation column, and subjected to fusel oil removal before being returned to the distillation apparatus. Fraction removal may be iteratively repeated but is preferably operated continuously throughout the distillation process.
The alcoholic aqueous fraction preferably has an alcohol content of 10% v/v or more.
Advantageously, it is between 10 and 40% v/v. Preferably, the alcohol content is between 20 and 30% v/v. The concentration of alcohol is thus lower than in the dilution methods used in the prior art.
Advantageously, the alcoholic aqueous fraction is removed at a temperature of between 80 and 98 C, preferably between 85 and 95 C, and most preferably at or around 90 C, at atmospheric pressure.
The alcoholic concentration and the temperature of the fraction removed from the distillation are linked. Thus, an aqueous alcoholic fraction removed from a grain distillation with a strength of 10% v/v will have a temperature of about 92 C, while a 40% fraction will have a temperature of about 82 C, at atmospheric pressure.
Different temperatures may be applicable at other pressures.
The alcoholic aqueous fraction may be cooled in one or more steps. For example, an efficient way initially to reduce the temperature is to pass the fraction issuing from the distillation apparatus to a first heat exchanger, wherein heat exchange takes place against processed aqueous alcoholic fraction material from which fusel oil has already been removed and which is being returned to the distillation apparatus.
Alternatively.
or. preferably. in addition, the fraction may be further cooled by refrigeration or further heat exchange steps. The fraction may be cooled by any suitable means.
such as refrigeration using coolants such as liquid nitrogen, but preferably it is cooled by ammonia evaporation.
The fraction is preferably cooled to below about 0 C, more preferably -5 C to -15 C, and advantageously around -10 C.
Fusel oil contained in the alcoholic aqueous fraction is preferably rendered substantially insoluble at the reduced temperature, and may be removed, for example by tapping off the fusel oil fraction in a separator vessel. The fusel oil being less dense than the alcoholic aqueous fraction, it rises to the top and may be removed from the surface of the alcoholic aqueous fraction.
By "substantially insoluble", it is intended that the fusel oil becomes insoluble in the alcoholic aqueous mixture to a point where it begins to come out of solution and form an independent liquid phase. This can be removed as described, for example in a separation vat.
Clearly, by chilling the alcoholic aqueous phase further, the fusel oil may be more efficiently removed therefrom, since its solubility therein will be further reduced.
Since the application of a low temperature step is necessary in the process according to the invention, it is referred to as freeze distillation.
In a preferred embodiment, therefore, the invention provides a freeze distillation process for preparing a freeze distilled alcohol, the process comprising partial or complete removal of fusel oil by the steps of:
(a) removing an alcoholic aqueous fraction comprising alcohol and fusel oil from the distillations;
(b) cooling the fraction to reduce the solubility of the fusel oil therein, rendering it substantially insoluble; and (c) separating the aqueous fraction from the fusel oil, and returning the thus separated aqueous fraction to the distillation.
As used herein. "freeze distillation" refers to a distillation process in which fusel oil is removed according to the invention as described above.
The distillation process may include further steps, depending on the final product which it is intended to produce. Thus, further distillation steps, optionally with flavourings, filtrations and the like may be included. Optionally, the distillation process may yield a spirit drink directly. In a preferred aspect, the invention provides a distillation process for the production of agricultural alcohol which involves the use of six distillation columns, namely an analyser, a rectifier, a hydroselection column, a concentration column, a finishing column and a feints and heads column. The alcohol is obtained at the bottom of the finishing column, and preferably has a strength of at least 96% v/v.
Further processing of the agricultural alcohol into a spirit drink, for example in the production of vodka, may involve dilution with water. For producing vodka, the use of softened mineral water is preferred, although demineralised water may also be used.
According to a second aspect of the invention, there is provided a freeze distilled alcohol. As used herein, a "freeze distilled" substance is an substance at least part of which is an alcohol which has been produced by a method as described in the first aspect of the invention. In a most preferred embodiment, the alcohol is ethanol. It is preferably used as the basis of alcoholic spirit drinks and other beverages.
The invention therefore also provides a freeze distilled alcoholic beverage made with an alcohol produced according to the invention.
Preferably, the alcoholic beverage has a final ethanol concentration of at least 15%.
Advantageously, the alcoholic beverage is freeze distilled vodka.
A third aspect of the invention provides an apparatus for distilling an alcohol.
comprising a distillation column, a withdrawing system for removing a fraction from the distillation apparatus. at least one heat exchanger or cooler. a separation vat and a replacing system reintroducing for material from the separation vat to the distillation column, wherein, in use. an alcoholic aqueous fraction comprising ethanol and fusel oil is taken from the distillation apparatus via the withdrawing system, cooled in the heat exchanger or cooler to a point such that the fusel oil becomes substantially insoluble in the alcoholic aqueous fraction, the fusel oil is separated from the alcoholic aqueous solution in the separation vat and the alcoholic aqueous fraction is returned to the distillation column via the replacing system.
The invention is further described, for the purposes of illustration only, in the examples below, in which reference is made to the following figures.
Modifications of the method within the scope of the present invention will be apparent to those skilled in the art.
Figure 1 is a diagram of the fusel oil removal apparatus in a freeze distillation process according to the invention. An alcoholic fraction is withdrawn from distillation column (1) by pump (2), at a temperature of 90 C (100 litres/h). This is passed sequentially through heat exchangers (3) and (4). in the latter of which it is cooled to -10 C by ammonia (8). The fraction then passes to separation tank (5) wherein the fuse] oil is separated and removed (6). Pump (7) removes the residual alcoholic fraction, which passes through heat exchanger (3) wherein it is warmed to approximately 78 C before being returned to the distillation column.
Figure 2 is a diagram of a six-column distillation apparatus used for the production of agricultural alcohol. Mash (10) is fed into analyser (B). Slops (11) are discarded, whilst the distillate (12) passes to the rectifier (L). A fraction is taken at (13) for fusel oil removal, with the distillate passing to hydroselection column (F). Heads (14) are removed. Water (15) is added, heads passing in part to the feints and heads column (E), and the remaining fluid passes to the concentration column (K). The distillate is passed to the finishing column (S), from which agricultural ethanol is obtained (16).
Example 1.
Laboratory scale distillation procedure Wheat grain is ground into flour and mixed with water, heated to 150 C for 3 minutes and allowed to cool to room temperature. Starch converting enzymes and yeast are added according to standard distillation protocols, and the mixture allowed to ferment for 3 days.
The fermented mash is then distilled on a distillation column according to standard procedures for the production of agricultural alcohol, as defined in EC
Regulation No 1576/89. From this distillation column an alcoholic aqueous fraction is taken at a temperature of 90 C. This fraction is an aqueous alcoholic fraction with an alcohol content of 19.6% v/v.
The fraction is cooled to -8 C. Fusel oil separates from the alcoholic aqueous phase and rises to the top surface, where it has a yellowish oily appearance. The alcoholic aqueous phase remains liquid, and no ice crystals are formed.
Analysis of both phases gives the following results:
Substance Oil phase (mg/11 Aqueous phase (mall) 1-propanol 200 100 2-methyl- l -propanol 26000 3000 1-butanol 300 60 3-methyl-l-butanol. 273000 8500 2-methyl- l -butanol 202000 6400 water 12.2 g/100ml A comparative assay, using the dilution methods of the prior art, yielded the following results:
Substance Oil phase (m(.,/1) Aqueous phase (mg/1) 1-propanol 300 200 2-methyl-l-propanol 31200 6500 1-butanol 600 120 3-methyl-l-butanol 341000 17000 2-methyl- l -butanol 253000 13000 water 10.5 g/100ml The results demonstrate superior removal of fusel oil from the aqueous phase by cooling than by dilution.
Example 2.
Industrial scale distillation A distillation system comprising 6 distillation columns (obtained from Vogelbusch, Vienna, Austria) as shown in figure 2 is set up according to conventional parameters for the production of agricultural alcohol. In a continuous process, mash derived from whole wheat grain is fermented conventionally and introduced into the distillation apparatus at a rate of 8 m3 per hour and heated to 90 C.
An aqueous fraction containing 25 % ethanol is taken from the distillation column.
This fraction, having a temperature of approx. 85 C' is led to heat exchanger 1 and is cooled as much as possible by means of the heat exchange with the lower phase from the separation vat. The liquid is subsequently led to heat exchanger 2 in which it is cooled to -10 C by direct evaporation of liquid ammonia.
Having been cooled down to this temperature, the liquid is led to a separation vat.
Here the fusel oil rises to the surface from where it is drawn off.
The lower phase is pumped directly to heat exchanger 1 in which the liquid is heated to approx. 72"C and then led back to the column.
The distillation is continued through 5 columns, as shown in figure 2, with residuals being purified in the sixth column.
By applying this new method an improved separation of fusel oil is obtained, wherein an approximate improvement of 3% is achieved in respect of alcohols having more than 4 carbon atoms. The composition of the fusel oil removed varies according to the raw material used, but in general fusel oil removed by the method of the invention comprises slightly more ethanol, since the percentage of ethanol in the aqueous mixture will be slightly higher that that in a mixture which has been separated by a dilution method.
The distilled ethanol is mixed with water to produce vodka spirit. Freeze distilled vodka prepared using freeze distilled ethanol subjectively has a smoother flavour.
When producing ethanol by fermentation, alcohols with more than two carbon atoms.
such as 2-Methyl-1-Propanol. 3-Methyl-l-Butanol and 2-Methyl-l-Butanol are formed during the fermentation process. Within the fermentation industry these alcohols are generally known as fusel oil.
Fuse] oil imparts an characteristic odour and taste to ethanol and is therefore traditionally removed therefrom during the distillation process. The removal of fusel oil from distilled ethanol has hitherto taken place by removing a fusel oil-containing fraction from the distillation column where the liquid phase has an alcoholic strength of 40-50% v/v. At this strength the fusel oil, which is soluble in ethanol but less soluble in aqueous mixtures, is kept dissolved in the eyhanol/water mixture.
In order to remove it, it has been necessary to add 11/,-2 volumes of water to the fraction in order to separate the fusel oil from the alcohol by rendering it insoluble in the ethanol/water mixture. Having a lower density, the fusel oil rises to the surface of the separation vat from where it can be drawn off, while the diluted ethanol/water mixture can be recycled to the distillation column.
There are several disadvantages associated with this system. For example, the continuous addition of water to the distillation process requires the input of additional energy in order to maintain a sufficient distillation temperature in the distillation column. An increase in the volume of waste water present in the bottom of the column will also occur, which can lead to capacity restrictions. Moreover, impurities in the added water may be deposited on the walls of the distillation column, which accordingly requires more frequent cleaning.
International Patent Application W094/21779 (Labatt Brewing Company Limited) describes a process for brewing fermented malt beverages, typically beer, in which a freezing step is used in order to cause ice crystal formation in the beer. The object of this process is to prevent "chill haze" and other problems normally associated with beer. Due to the formation of ice crystals during the chilling process. beers produced by such methods are often referred to as "Ice" beers. The process effectively allows the removal of water from the brew but is not suitable for removal of fuse]
oil.
The present invention overcomes the problems of the prior art by providing a method for preparing a distilled alcohol or a distilled alcoholic beverage which comprises the removal of fusel oil contaminants at a reduced temperature.
According to a first aspect of the present invention, there is provided a process for removing fusel oil from an aqueous alcoholic medium, comprising the steps of:
(a) cooling the medium to effect separation of fusel oil from the medium; and (b) removing at least part of the fusel oil from the medium.
A fusel oil. as referred to herein, is an alcohol or mixture of alcohols having more than two, typically four or more, carbon atoms, whose presence in alcoholic solutions may be undesirable on account of its characteristic effect on taste and/or aroma. By reducing the temperature of alcoholic aqueous media containing fusel oil, the solubility of the fusel oil in the solution may be reduced, to the point where it no longer remains in solution. The fusel oil being lighter than aqueous alcohol, the medium separates into two phases, and the fusel oil phase may be removed. A
better separation of fusel oil from the alcoholic aqueous phase is thus obtained than is possible through conventional dilution processes.
Agricultural alcohol is produced by distillation of a variety of raw materials from agricultural sources, for example potato and grain. This spirit is the basis of a variety of alcoholic beverages, such as bitters, aquavit, gin and vodka. The production of, for example, aquavit, may require a second distillation step, and have flavouring substances added thereto, while others, such as vodka, may be subjected to only a single distillation, and possibly also a filtration step.
As used herein. "Agricultural alcohol-, "ethanol" and "spirit drink". as well as "vodka" and the snecific names of other alcoholic beverages, are as defined in EC
Directive 1576/89 of 29th May 1989, incorporated herein by reference.
"Ethanol" is synonymous with "ethyl alcohol", and "agricultural alcohol" is synonymous with "agricultural ethyl alcohol".
The removal of fusel oil according to the present invention is carried out during the distillation. An alcoholic aqueous fraction containing fusel oil is removed from the distillation apparatus, which is typically a distillation column, and subjected to fusel oil removal before being returned to the distillation apparatus. Fraction removal may be iteratively repeated but is preferably operated continuously throughout the distillation process.
The alcoholic aqueous fraction preferably has an alcohol content of 10% v/v or more.
Advantageously, it is between 10 and 40% v/v. Preferably, the alcohol content is between 20 and 30% v/v. The concentration of alcohol is thus lower than in the dilution methods used in the prior art.
Advantageously, the alcoholic aqueous fraction is removed at a temperature of between 80 and 98 C, preferably between 85 and 95 C, and most preferably at or around 90 C, at atmospheric pressure.
The alcoholic concentration and the temperature of the fraction removed from the distillation are linked. Thus, an aqueous alcoholic fraction removed from a grain distillation with a strength of 10% v/v will have a temperature of about 92 C, while a 40% fraction will have a temperature of about 82 C, at atmospheric pressure.
Different temperatures may be applicable at other pressures.
The alcoholic aqueous fraction may be cooled in one or more steps. For example, an efficient way initially to reduce the temperature is to pass the fraction issuing from the distillation apparatus to a first heat exchanger, wherein heat exchange takes place against processed aqueous alcoholic fraction material from which fusel oil has already been removed and which is being returned to the distillation apparatus.
Alternatively.
or. preferably. in addition, the fraction may be further cooled by refrigeration or further heat exchange steps. The fraction may be cooled by any suitable means.
such as refrigeration using coolants such as liquid nitrogen, but preferably it is cooled by ammonia evaporation.
The fraction is preferably cooled to below about 0 C, more preferably -5 C to -15 C, and advantageously around -10 C.
Fusel oil contained in the alcoholic aqueous fraction is preferably rendered substantially insoluble at the reduced temperature, and may be removed, for example by tapping off the fusel oil fraction in a separator vessel. The fusel oil being less dense than the alcoholic aqueous fraction, it rises to the top and may be removed from the surface of the alcoholic aqueous fraction.
By "substantially insoluble", it is intended that the fusel oil becomes insoluble in the alcoholic aqueous mixture to a point where it begins to come out of solution and form an independent liquid phase. This can be removed as described, for example in a separation vat.
Clearly, by chilling the alcoholic aqueous phase further, the fusel oil may be more efficiently removed therefrom, since its solubility therein will be further reduced.
Since the application of a low temperature step is necessary in the process according to the invention, it is referred to as freeze distillation.
In a preferred embodiment, therefore, the invention provides a freeze distillation process for preparing a freeze distilled alcohol, the process comprising partial or complete removal of fusel oil by the steps of:
(a) removing an alcoholic aqueous fraction comprising alcohol and fusel oil from the distillations;
(b) cooling the fraction to reduce the solubility of the fusel oil therein, rendering it substantially insoluble; and (c) separating the aqueous fraction from the fusel oil, and returning the thus separated aqueous fraction to the distillation.
As used herein. "freeze distillation" refers to a distillation process in which fusel oil is removed according to the invention as described above.
The distillation process may include further steps, depending on the final product which it is intended to produce. Thus, further distillation steps, optionally with flavourings, filtrations and the like may be included. Optionally, the distillation process may yield a spirit drink directly. In a preferred aspect, the invention provides a distillation process for the production of agricultural alcohol which involves the use of six distillation columns, namely an analyser, a rectifier, a hydroselection column, a concentration column, a finishing column and a feints and heads column. The alcohol is obtained at the bottom of the finishing column, and preferably has a strength of at least 96% v/v.
Further processing of the agricultural alcohol into a spirit drink, for example in the production of vodka, may involve dilution with water. For producing vodka, the use of softened mineral water is preferred, although demineralised water may also be used.
According to a second aspect of the invention, there is provided a freeze distilled alcohol. As used herein, a "freeze distilled" substance is an substance at least part of which is an alcohol which has been produced by a method as described in the first aspect of the invention. In a most preferred embodiment, the alcohol is ethanol. It is preferably used as the basis of alcoholic spirit drinks and other beverages.
The invention therefore also provides a freeze distilled alcoholic beverage made with an alcohol produced according to the invention.
Preferably, the alcoholic beverage has a final ethanol concentration of at least 15%.
Advantageously, the alcoholic beverage is freeze distilled vodka.
A third aspect of the invention provides an apparatus for distilling an alcohol.
comprising a distillation column, a withdrawing system for removing a fraction from the distillation apparatus. at least one heat exchanger or cooler. a separation vat and a replacing system reintroducing for material from the separation vat to the distillation column, wherein, in use. an alcoholic aqueous fraction comprising ethanol and fusel oil is taken from the distillation apparatus via the withdrawing system, cooled in the heat exchanger or cooler to a point such that the fusel oil becomes substantially insoluble in the alcoholic aqueous fraction, the fusel oil is separated from the alcoholic aqueous solution in the separation vat and the alcoholic aqueous fraction is returned to the distillation column via the replacing system.
The invention is further described, for the purposes of illustration only, in the examples below, in which reference is made to the following figures.
Modifications of the method within the scope of the present invention will be apparent to those skilled in the art.
Figure 1 is a diagram of the fusel oil removal apparatus in a freeze distillation process according to the invention. An alcoholic fraction is withdrawn from distillation column (1) by pump (2), at a temperature of 90 C (100 litres/h). This is passed sequentially through heat exchangers (3) and (4). in the latter of which it is cooled to -10 C by ammonia (8). The fraction then passes to separation tank (5) wherein the fuse] oil is separated and removed (6). Pump (7) removes the residual alcoholic fraction, which passes through heat exchanger (3) wherein it is warmed to approximately 78 C before being returned to the distillation column.
Figure 2 is a diagram of a six-column distillation apparatus used for the production of agricultural alcohol. Mash (10) is fed into analyser (B). Slops (11) are discarded, whilst the distillate (12) passes to the rectifier (L). A fraction is taken at (13) for fusel oil removal, with the distillate passing to hydroselection column (F). Heads (14) are removed. Water (15) is added, heads passing in part to the feints and heads column (E), and the remaining fluid passes to the concentration column (K). The distillate is passed to the finishing column (S), from which agricultural ethanol is obtained (16).
Example 1.
Laboratory scale distillation procedure Wheat grain is ground into flour and mixed with water, heated to 150 C for 3 minutes and allowed to cool to room temperature. Starch converting enzymes and yeast are added according to standard distillation protocols, and the mixture allowed to ferment for 3 days.
The fermented mash is then distilled on a distillation column according to standard procedures for the production of agricultural alcohol, as defined in EC
Regulation No 1576/89. From this distillation column an alcoholic aqueous fraction is taken at a temperature of 90 C. This fraction is an aqueous alcoholic fraction with an alcohol content of 19.6% v/v.
The fraction is cooled to -8 C. Fusel oil separates from the alcoholic aqueous phase and rises to the top surface, where it has a yellowish oily appearance. The alcoholic aqueous phase remains liquid, and no ice crystals are formed.
Analysis of both phases gives the following results:
Substance Oil phase (mg/11 Aqueous phase (mall) 1-propanol 200 100 2-methyl- l -propanol 26000 3000 1-butanol 300 60 3-methyl-l-butanol. 273000 8500 2-methyl- l -butanol 202000 6400 water 12.2 g/100ml A comparative assay, using the dilution methods of the prior art, yielded the following results:
Substance Oil phase (m(.,/1) Aqueous phase (mg/1) 1-propanol 300 200 2-methyl-l-propanol 31200 6500 1-butanol 600 120 3-methyl-l-butanol 341000 17000 2-methyl- l -butanol 253000 13000 water 10.5 g/100ml The results demonstrate superior removal of fusel oil from the aqueous phase by cooling than by dilution.
Example 2.
Industrial scale distillation A distillation system comprising 6 distillation columns (obtained from Vogelbusch, Vienna, Austria) as shown in figure 2 is set up according to conventional parameters for the production of agricultural alcohol. In a continuous process, mash derived from whole wheat grain is fermented conventionally and introduced into the distillation apparatus at a rate of 8 m3 per hour and heated to 90 C.
An aqueous fraction containing 25 % ethanol is taken from the distillation column.
This fraction, having a temperature of approx. 85 C' is led to heat exchanger 1 and is cooled as much as possible by means of the heat exchange with the lower phase from the separation vat. The liquid is subsequently led to heat exchanger 2 in which it is cooled to -10 C by direct evaporation of liquid ammonia.
Having been cooled down to this temperature, the liquid is led to a separation vat.
Here the fusel oil rises to the surface from where it is drawn off.
The lower phase is pumped directly to heat exchanger 1 in which the liquid is heated to approx. 72"C and then led back to the column.
The distillation is continued through 5 columns, as shown in figure 2, with residuals being purified in the sixth column.
By applying this new method an improved separation of fusel oil is obtained, wherein an approximate improvement of 3% is achieved in respect of alcohols having more than 4 carbon atoms. The composition of the fusel oil removed varies according to the raw material used, but in general fusel oil removed by the method of the invention comprises slightly more ethanol, since the percentage of ethanol in the aqueous mixture will be slightly higher that that in a mixture which has been separated by a dilution method.
The distilled ethanol is mixed with water to produce vodka spirit. Freeze distilled vodka prepared using freeze distilled ethanol subjectively has a smoother flavour.
Claims (15)
1. A freeze distilled alcohol.
2. A freeze distilled alcoholic beverage comprising freeze distilled alcohol according to claim 1.
3. Freeze distilled vodka.
4. A process for removing fusel oil from an aqueous alcoholic medium, comprising the steps of:
(a) cooling the medium to effect separation of fusel oil from the medium; and (b) removing at least part of the fusel oil from the medium.
(a) cooling the medium to effect separation of fusel oil from the medium; and (b) removing at least part of the fusel oil from the medium.
5. A freeze distillation process for preparing a freeze distilled alcohol, the process comprising partial or complete removal of fusel oil by the steps of:
(a) removing an alcoholic aqueous fraction comprising ethanol and fusel oil from the distillation;
(b) cooling the fraction to reduce the solubility of the fusel oil therein;
and (c) separating the aqueous fraction from the fusel oil, and returning the thus separated aqueous fraction to the distillation.
(a) removing an alcoholic aqueous fraction comprising ethanol and fusel oil from the distillation;
(b) cooling the fraction to reduce the solubility of the fusel oil therein;
and (c) separating the aqueous fraction from the fusel oil, and returning the thus separated aqueous fraction to the distillation.
6. A process according to claim 5, wherein the distillation process comprises a single distillation step.
7. A process according to any one of claims 4 to 6, wherein the alcoholic aqueous fraction comprises between 20% and 30 % ethanol.
8. A process according to any one of claims 4 to 7, wherein the alcoholic aqueous fraction is taken from the distillation column at a temperature of between 80 and 95°C.
9. A process according to any one of claims 4 to 8, wherein the alcoholic aqueous fraction is cooled to below 0°C.
10. A process according to claim 9, wherein the alcoholic aqueous fraction is cooled to between -5°C and -15°C.
11. A process according to claim any one of claims 5 to 10, wherein the fusel oil is rendered substantially insoluble in the alcoholic aqueous fraction by cooling.
12. A process according to any one of claims 4 to 11, wherein the alcohol has a final concentration of at least 96 % v/ v.
13. A process according to any one of claims 3 to 12, wherein the alcohol is employed in the production of an alcoholic beverage.
14. An apparatus for distilling an alcohol, comprising a distillation column, a withdrawing system for removing a fraction from the distillation apparatus, at least one heat exchanger or cooler, a separation vat and a replacing system reintroducing for material from the separation vat to the distillation column, wherein, in use, an alcoholic aqueous fraction comprising ethanol and fusel oil is taken from the distillation apparatus via the withdrawing system, cooled in the heat exchanger or cooler to a point such that the fusel oil becomes substantially insoluble in the alcoholic aqueous fraction, the fusel oil is separated from the alcoholic aqueous solution in the separation vat and the alcoholic aqueous fraction is returned to the distillation column via the replacing system.
15. A distillation apparatus as hereinbefore described, with reference to the drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9702659A GB2305935B (en) | 1997-02-10 | 1997-02-10 | Freeze distillation process and alcohol-containing product |
| GB9702659.5 | 1997-02-10 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2228908A1 CA2228908A1 (en) | 1998-08-10 |
| CA2228908C true CA2228908C (en) | 2010-06-29 |
Family
ID=10807352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2228908A Expired - Lifetime CA2228908C (en) | 1997-02-10 | 1998-02-05 | Distillation method |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH10215856A (en) |
| CA (1) | CA2228908C (en) |
| DE (1) | DE19804130A1 (en) |
| DK (1) | DK18498A (en) |
| GB (1) | GB2305935B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LV13003B (en) | 2002-10-03 | 2003-07-20 | Spirits Product Internat Intel | Method for processing vodka |
| ES2350603T3 (en) * | 2007-06-26 | 2011-01-25 | Foss Analytical A/S | DEVICE AND METHOD FOR ANALYSIS OF A VINIFICATION LIQUID. |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1570944A (en) * | 1977-03-19 | 1980-07-09 | Douwe Egberts Tabaksfab | Process for the concentration of aqueous solutions |
| GB2261442A (en) * | 1991-11-08 | 1993-05-19 | David George Pollard | Process for freeze-concentrating beer |
| US5304384A (en) * | 1993-03-23 | 1994-04-19 | Labatt Brewing Company Limited | Improvements in production of fermented malt beverages |
-
1997
- 1997-02-10 GB GB9702659A patent/GB2305935B/en not_active Expired - Lifetime
-
1998
- 1998-02-03 DE DE19804130A patent/DE19804130A1/en not_active Withdrawn
- 1998-02-05 CA CA2228908A patent/CA2228908C/en not_active Expired - Lifetime
- 1998-02-09 DK DK199800184A patent/DK18498A/en not_active Application Discontinuation
- 1998-02-10 JP JP2823398A patent/JPH10215856A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DK18498A (en) | 1998-08-11 |
| GB2305935A (en) | 1997-04-23 |
| JPH10215856A (en) | 1998-08-18 |
| DE19804130A1 (en) | 1998-08-13 |
| GB2305935B (en) | 1997-10-01 |
| CA2228908A1 (en) | 1998-08-10 |
| GB9702659D0 (en) | 1997-04-02 |
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