GB2084607A - Method for the production of low alcohol beverages - Google Patents

Abstract

A low alcohol beverage is produced by removing alcohol from an alcoholic beverage, in which the alcoholic beverage is passed down a column 4 suitable for fractional distillation, while steam is passed up the column to strip alcohol from the beverage, the required low alcohol beverage being recovered from the lower part of the column while steam from the upper part of the column is condensed to form an alcoholic condensate, the pressure within the column being sub-atmospheric and the steam being at a temperature compatible with flavour components of the beverage. The feed to the column may be preheated by the low alcohol product, by heat exchanger 3, and may be degassed prior to passing to the column. The column may be a packed column with 6 to 8 theoretical plates. <IMAGE>

Description

SPECIFICATION Method for the production of low alcohol beverages This invention relates to beverages produced by fermentation and which have a low alcohol (ethanol) content.

Considerable interest has recently arisen in beverages which would normally be alcoholic, such as beers, lagers and wines but which have a low alcohol content or are substantially free of alcohol. Such low alcohol beverages are of especial interest to those who wish to enjoy the pleasures of drinking beverages which normally contain alcohol but who, for one reason or another, wish to avoid the intoxicating effects of alcohol, for example when driving a motor vehicle or for medical reasons.

Low alcohol beverages have previously been prepared by removing alcohol from beverages containing alcohol produced by fermentation processes. For example, low alcohol lager, has been prepared by subjecting conventional lager to evaporation in a flat plate evaporator whereby the alcohol is removed. However, in such an evaporation process large amounts of water are simultaneously evaporated from the starting lager, and for example when it is desired to obtain a product containing about 0.1% of alcohol it Is necessary simultaneously to remove about 70% of the original water. Such water evaporation represents a large and wasteful use of energy.

In general, it is found that a single pass through such equipment is insufficient to bring about the degree of evaporation which is necessary for alcohol removal and various methods are employed to overcome this problem. One such method is to pass each batch of lager several times through the evaporator, whilst in other cases batches of lager are continuously recirculated through the evaporator until the necessary evaporation has been achieved.

The two processes described above are successful in achieving the required evaporation but they offer no improvement in energy consumption. One method by which the energy requirement may be reduced is to use multi-effect evaporation as is known in the art. In this process, the vapour generated by each stage of evaporation is condensed in the heater of each succeeding stage where it brings about an approximately equal quantity of further evaporation. In practice, however, the multiple equipment required together with the very small temperature differentials available at each heating surface lead to very high capital costs.

In order to avoid deterioration of the beverage flavours it is generally necessary to effect the alcohol separation at a low temperature, for example 30 to 600 C, under reduced pressure and also to minimise the duration of the process, since flavour damage is time dependent. Typically the process time should not exceed two minutes at 600 C, conditions which are likely to be exceeded in all of the processes described above. British Patent Specification No. 371 671 describes a process for the removal of alcohol from alcoholic liquids such as wine, cider and beer by a form of steam stripping.In one embodiment which is described, alcohol is removed from wine after solvent extraction of flavour components by passing the wine in a finely atomised state down a column while water vapour is passed up through the column. The alcohol removal is effected at a low temperature (300C is exemplified) and low pressure. The column for use in the process has no internal features, apart from the atomising nozzle and a nozzle for introducing the water vapour, and does not contain packing elements or similar fractionating means characteristic of a fractional distillation column. In such a system, transfer of material between the atomised droplets of beverage and the steam would be low and separation would thus be poor.

We have now devised a simple and rapid method of producing low alcohol beverages while substantially avoiding deleterious effects on flavours and reducing the use of steam approximately to the amount required to evaporate only the alcohol removed. Our new method essentially involves the removal of alcohol from an alcohol-containing beverage by steam stripping under reduced pressure in a fractionating column. The upper limit to the temperature at which the steam stripping is effected generally depends on the thermal stability of the flavours of the starting beverage, which may, for example, be beer, lager, wine and the like, and we have found it convenient, particularly in the case of beer and lager, to effect the stripping at a relatively low temperature e.g. not greater than about 60 C and preferably at about 550C.

In this way the alcoholic beverage is substantially stripped of alcohol as it passes downwardly through the column by the upwardly passing steam without contacting localised hot surfaces such as are commonly present when direct heating is employed. The desired substantially alcohol-free beverage is removed from the bottom of the column while steam containing the removed alcohol is taken from the top of the column and is subsequently condensed or otherwise disposed of. In this way it is possible to obtain a beverage containing down to about 0.1% by volume of alcohol or even less.

According to the present invention, therefore, we provide a method of producing a low alcohol beverage by removal of alcohol from an alcoholic beverage wherein the alcoholic beverage is passed down a column containing packing or like elements suitable for fractional distillation, while steam is passed up the column to strip alcohol from the beverage, the required low alcohol beverage being recovered from the lower part of the column while steam from the upper part of the column is condensed to form an alcoholic condensate, the pressure within the column being sub-atmospheric and the steam being at a temperature compatible with flavour components of the beverage.

It is found that the residence time of the beverage in the distillation column may be held well below 2 minutes by appropriate apparatus and process design.

The quantity of steam required to remove virtually all of the alcohol from the beverage depends on the pressure and temperature in the column and other parameters of the system. The weight ratio of starting beverage to steam is advantageously in the range 3 to 5, for example about 4. The concentration of alcohol in the steam condensate is, approximately equal to the product of this ratio and the initial concentration of alcohol in the beverage and is commonly of the order of 20%. In some cases, the condensate can itself be used as a beverage or in the fortification of other beverages. In general, the prior art process described above gives condensates at much lower alcohol concentrations, which are less useful.

It will be noted that one advantgage of the present process is that it is not necessary to add replacement water to the product as is required in the above prior art process. Sterile, demineralised and deaerated water has to be used in the prior process, whereas the steam used in the present process is automatically sterilised and demineralised in the boiler and deaerated in the vacuum distillation column.

The steam used in the method of the invention may be supplied by a conventional process line with suitable pressure reduction, but is preferably obtained from a vacuum boiler fed preferably with softened water, in order to avoid scaling, and heated by plant process steam. The low pressure in the system can be maintained by, for example, a mechanical vacuum pump or by a steam ejector.

The fractional distillation column used in the method of the invention may be of conventional construction, e.g. a column packed with an inert solid material such as raschig rings or suitable proprietary packing. In general we have found that packed columns are preferred to plate or tray columns because of their lower hold-up volume.

The number of theoretical plates required for a given alcohol removal in any particular case may be determined by design procedures known in the art and will vary according to the concentration of alcohol in the feed beverage, the concentration of alcohol desired in the product and the energy economy required of the process. When, for example, it is desired to reduce the alcohol content of a typical starting lager to about 0.1% by volume we have found it convenient to use a fractional distillation column having 6 to 8 theoretical plates.

In order to reduce the energy requirement for the method of the invention it is convenient to pass the feedstock beverage through a heatexchanger to raise its temperature before passing it to the fractional distillation column. The output low alcohol beverage from the column can thus be passed through the other circuit of the heatexchanger whereby it is cooled. Similarly, the incoming process water fed to the vacuum boiler can be used to cool the steam condensate.

Precautions are generally necessary to minimise the generation of foam within the column which may arise due to the surface-active nature of some starting beverages. If foam generation was allowed to take place, this would cause liquid locking of the distillation column and loss of product in the vapour.

We have found that foam generation may be kept within acceptable limits by degassing the starting beverage in a vacuumn chamber prior to its introduction into the distillation column. The vacuum chamber may conveniently be held at the pressure obtaining in the distillation column and at ambient temperature, e.g. between 1 5 and 200 C.

Foam generation may also be conveniently controlled by ensuring that the starting beverage is injected into a packed fractional distillation column below the top of the packing, e.g. at a level of at least 0.3 metres below the top of the packing.

As indicated above, the method of the invention may be used to produce beverages which have a low alcohol content, or are substantially free of alcohol, from beer, lager, wine and the like, which may normally have alcohol concentrations in the range 4 to 12% by volume.

The invention will now be illustrated with reference to the Figure of the accompanying drawing which schematically shows apparatus for effecting the method.

In the method using the apparatus shown in the Figure, lager produced by normal brewing techniques and containing about 4.2% by volume of alcohol is pumped from storage to vessel 1 where, through the continuous application of vacuum by pump 10, the lager is degassed at ambient temperature. The lager is pumped to a heat-exchanger 3 by pump 2, and is then introduced into the top of fractional distillation column 4. The fractional distillation column 4 is in the form of a column packed with glass rings and has approximately 7 theoretical plates below the feed point, which is at a level approximately 0.3 metres below the top of the packing.

Softened water is fed to boiler 5 and the steam produced therein having a temperature of about 550C is then passed to the bottom of column 4.

The boiler 5 is heated by steam from a plant process supply. The steam from boiler 5 passes up the column 4, wherein it is also at a temperature of about 550C, and serves to strip the alcohol from the downwardly passing lager. Steam containing about 20% by volume of alcohol vapour is removed from the top of column 4 and this passes to the water-cooled condenser 8 and thence to a sealed receiving vessel (not shown).

A reduced pressure is maintained in column 4 by means of vacuum pump 9 attached to the steam/alcohol output line.

When the lager reaches the bottom of the column 4, substantially all of the alcohol has been stripped therefrom; it then has an alcohol content of less than about 0.1% by volume. The substantially alcohol-free lager is pumped from the column 4 by pump 6 and is cooled by being passed through heat-exchanger 3 before passing to storage vessel 7.

In general, the equipment described above is simpler and therefore less expensive than the evaporation equipment of the above prior art process. Furthermore, for the production of the same volume of alcohol free beverage, significantly less cooling water is used, thus reducing effluent problems and the overall energy input in terms of generation of process steam and electricity for running vacuum pumps is very much reduced.

Claims (13)

1. A method of producing a low alcohol beverage by removal of alcohol from an alcoholic beverage wherein the alcoholic beverage is passed down a column containing packing or like elements suitable for fractional distillation, while steam is passed up the column to strip alcohol from the beverage, the required low alcohol beverage being recovered from the lower part of the column while steam from the upper part of the column is condensed to form an alcoholic condensate, the pressure within the column being sub-atmospheric and the steam being at a temperature compatible with flavour components of the beverage.

2. A method according to claim 1 wherein the beverage has a residence time in the column of not more than 2 minutes.

3. A method according to either of claims 1 and 2 wherein the weight ratio of alcoholic beverage passed down the column to steam passed up the column is from 3 to 5.

4. A method according to any one of the preceding claims wherein the column is a packed column.

5. A method according to any one of the preceding claims wherein the alcoholic beverage is passed through one circuit of a heat-exchanger to raise its temperature prior to passing it to the column, the low alcohol beverage removed from the column being passed through the other circuit of the heat-exchanger.

6. A method according to any one of the preceding claims wherein the low alcohol beverage removed from the column has an alcohol content of less than about 0.1% by volume.

7. A method according to any one of the preceding claims wherein the alcoholic beverage is beer or lager.

8. A method according to claim 7 wherein the temperature of the steam is not greater than about 600 C.

9. A method according to either of claims 7 and 8 wherein the column has from 6 to 8 theoretical plates.

10. A method according to any one of claims 7 to 9 wherein the beer or lager is degassed in a vacuum chamber prior to its introduction into the column.

11. A method according to any one of claims 7 to 10 wherein a packed column is used and the beer or lager is introduced into the column at a point below the top of the packing.

12. A method according to any one of the preceding claims substantially as herein described with reference to the accompanying drawing.

13. A low alcohol beverage produced by a method according to any one of the preceding claims.