GB2076852A - Method of preparing a diet beer - Google Patents

Abstract

A low-carbohydrate, alcohol- reduced, low-calorie diet beer is produced by evaporation under vacuum in a thin-film evaporator at 30-50 DEG C for 1-10 seconds to reduce the alcohol content with possible dilution of the beer before or after evaporation. Dextrins in the wort may be converted to fermentable carbohydrates by adding diastase solution. <IMAGE>

Description

SPECIFICATION Method of preparing a diet beer The invention relates to a method of preparing a low-carbohydrate, alcohol-reduced and low-calorie diet beer, wherein the wort is fermented in such a way that the fermentable carbohydrates and the dextrins, which can be fermented only with difficulty and which are converted to fermentable carbohydrates by adding diastase solution, are fermented to at least 0.75 g charging carbohydrates per 100 ml beer, and the alcohol content of the beer is reduced under vacuum, particularly using a wortwith an actual original wort content of 11 to 14%, or 16 to 20% for a strong beer.

The first diet beers to become known were those where the alcohol content was higher than that of normal beers. Dilution of this beer with a low percentageone,-as has been done in several processes to reduce the alcohol content, has proved disadvantageous because highiy fermented beers and therefore the blended beer do not have good body.

A method of preparing low-alcohol or alcohol-free beer is known from DE-AS 12 66 266, wherein a beer made in known manner is evaporated under vacuum, to expel a larger or smaller portion of its alcohol content, and the resultant residue is blended back and impregnated with carbon dioxide. Before entering the vacuum process, the beer which has to be dealcoholised is heated under pressure to a temperature higher than that of the beer in the vacuum tank. This beer is then subjected to spray evaporation under vacuum. The resultant de-gassed and partly dealcoholised beer is removed from the vacuum tank, reheated, returned to the vacuum tank and subjected to thin-layer evaporation.This second heating step, together with the thin-layer evaporation, is carried out as a cyclic process, until the beer is restricted to at least 85 to 90% and preferably to 70 to 80% of its initial volume, after which a quantity of low alcohol distillation residue equivalent to the beer supplied is constantly removed in a continuous process. According to this publication, tests on the constituents which give a beer its flavour show that the alcohol and some other volatile material obviously have little effect. To avoid oxidation processes, dealcoholisation in the presence of live yeast is recommended.

A method is known from DE-AS 14 42 238, for making alcohol reduced beer, using fully brewed beer as the starting product. The alcohol is separated under vacuum in a thin-layer evaporator and the cooled portion, freed from alcohol, is carbonised. The alcohol vapours, which are expelled from the beer at the evaporating stage at tem peratures below 70"C, are continuously condensed. The characteristic non-volatile aromatic substances are separated from the vapours by counter current distillation. The aromatic substances, still present from the simultaneously expelled carbon dioxide, are enriched therein by washing, and the aromatic mixture is fed back to the dealcoholised concentrate.The beer is heated to approximately 45"C, while the operation at the thin-layer evaporator takes place between 65 and 70"C. Comparison of the resultant beer shows all data determining the value and aroma of the drink to be virtually in agreement apart from the alcohol content. In flavour the alcohol reduced end product is indeed "thinner" and inevitably tastes somewhat less expressive than the original beer. However, there is absolutely no taste of oxidation through ageing or any undesirable harsh or bitter, tannin-like tang. No difference in the perception of smell are said to have been found between the two beers compared.

A method of making a refreshing drink is known from AT-PS 264427, published 15.12.1967. In this method beer undergoes vacuum dealcolisation, and the residue obtained, which may be dealcoholised to a greater or lesser extent, is impregnated with CO2. The process is characterised in that beer is treated in an installation where the air is supplanted by carbon dioxide; that it is initially heated and relaxed at a first (intake) stage, ieading to degasification, when the foam separated is removed; that the degassed and defoamed, heated beer is dealcoholised to a greater or less degree in a distillation column, during a second (separating) stage at elevated temperature and under vacuum, a concentrate rich in alcohol being withdrawn substantially in the middle of the column; whereupon the dealcoholised product (discharge) obtained as an absorption layer (Sumpf) in this separating stage is mixed with the foam removed at the first stage, then cooled to 6 to 12"C; and that in a third (post treatment) stage the product is mixed with the separately removed top product of the distillation column (containing substantially wort and aromatic substances and CO2 but no alcohol) and impregnated with CO2; and this may be followed by mixing with ordinary beer.

Vacuum evaporation may take place in a thin-iayer evaporator for a short period and at a temperature of 30 to 50"C. The essence of the invention is chiefly that the foam of the starting product, which is liberated at the first stage of treatment and which contains important aromatic and wort substances, is separated and returned to the process unaffected, at a point where the substances can no longer be changed. The decisive factor is thus that the foam containing the important aromatic and wort substances to be separated at a first stage of the treatment and not fed to the second, separating stage, where dealcoholisation under vacuum takes place, if any stage in these substances is to be avoided.Furthermore, with a refreshing drink in contrast to a diet beer, one does not have to master the problem of foam, so that a head of foam can be formed on either a draught diet beer or one which is poured in another manner.

A method of the type described at the beginning is known from DE-PS 20 52963. The wort used has an actual original wort content of 11 to 14%, or 16 to 20% for a strong beer. In a first phase of fermentation the wort is only partly femented, to an apparent fermentation degree of 40 to 70% extract. Fermentation is then interrupted and the young beer is boiled until the alcohol content is reduced to approximately 1% by weight.

Fermentation is completed in a second phase which follows. During this phase a temperature of from 12 to 20"C is set and a diastase solution with an increased content of limit dextrinases is added. When the second fermentation phase is over, the young beer is cooled and left standing for a short time to precipitate the substances making it turbid. A modification of this process is characterised in that, when a beer which has been fermented to an apparent degree of 75 to 85%, preferably 80%, has been boiled, the diastase solution enriched with limit dextrinases is added to it for further fermentation, and 50 to 150, preferably 100% by volume of the same initial wort is also added. In this process further quantities of yeast and enzymes relevant to the decomposition of carbohydrates (amylases) must be added after the reduction of the alcohol content.

It was known from Ullmanns Enzyklopädie der technischen Chemie, Volume 2, 1972, pages 656 and 657 that in alcohol distillation the residence time of the products to be vaporized can be reduced approximately one second in a Centrither evaporator. However, the commercially available evaporator was not suitable for reducing the alcohol in a beer because of the frothing problems which arise.

The actual course of technical development to shortly before the application date of the invention is characterised by DE-AS 2901 366 and DE-AS 29 24 283, neither of which is a prior publication. Large breweries have carried out corresponding brewing processes. The first mentioned method of making a low carbohydrate, alcohol reduced and low calorie diet beer, using wort with an original wort content of 11 to 11.5%, enzyme-rich malt and with boiling off of alcohol, is characterised by the following features.A wort with an original wort content of 11 to 11.5% is brought to fermentation with starting temperatures between 5 and 1 0C and following the addition of enzyme-rich bruised malt amounting to approximately 2% of the original fill, and a quantity of yeast larger than the usual amount in normal full beer production. The fermenting temperature gradually rises to approximately 20 C, since the fermenting heat is not dissipated, and an apparent fermentation degree of approximately 10isreaehed during this approximately 8-day main fermentation step.A portion taking in about two-fifths to three-fifths of the total quantity is removed from the fermentation vat, and almost boiling water amounting to 8 to 15% of the young beer addition is placed in a boiling vessel without any contact with oxygen. The portion removed from the vat is boiled in the vessel until the alcohol content drops to 1 to 2% by weight, with simultaneous evaporation of water to the extent of the amount of hot water used.When the alcohol-reduced young beer has been cooled, it is blended with the remainder of the young beer, which has in the meantime been transferred from the fermentation vat to storage vessels, and with small quantities of yeast contained therein, without any contact with oxygen, form an alcohol-reduced complete product; the final feature being that after a relatively short postfermentation stage the beer is filtered and decanted with fermentation carbon dioxide added to it. The other publication concerns a method of making fermented drinks such as beer, wine, champagne and the like with a reduced alcohol content, wherein a fermented drink prepared by the usual fermentation process is passed along a dialysis membrane with a differential pressure of less than 0.5 bar, while a dialysate fluid flows simultaneously along the other side of the membrane.

The problem to be solved against the background of this prior art was to enable a low-carbohydrate, alcohol-reduced and thus low-calorie diet beer of improved quality and particularly flavour to be brewed in a simplified, particularly a continuous process; the scope for variation in carrying out the step of alcohol reduction from an at least partly fermented beer must allow for improved adaptation to the timing of each requirement.

According to the invention the problem is solved, in that alcohol reduction takes place in a thin-layer evaporator at a temperature of 50"C, preferably 30"C, and for a short period, preferably from 1 to 10 seconds, and.that where wort with an originally high wort content i.e. in excess of 8%, e.g. 11 to 14% or 16 to 20%, is used, either the beer is diluted with oxygen-free water before the alcohol is reduced, or the alcohol-reduced beer is diluted back with oxygen-free water. The invention has a series of advantages going beyond the improvement in quality, particularly flavour.

If the alcohol is reduced in accordance with an advantageous embodiment of the invention, during the main fermentation by means of a slip stream the process can be carried out continuously, not necessarily in the brewing house but also in the fermentation cellar.

The method of the invention is less harmful to the enviroment than the method known from DE-PS 20 52 963. The alcohol separated is not discharged but is collected and can consequently be made useful for other purposes.

A further advantage is the very low absorption of oxygen, since alcohol reduction takes place within a closed system. Excessive absorption of oxygen is known to be detrimental to the quality of the beer.

None of the bouquet substances in the byproducts of fermentation which are conducive to the flavour are lost. They can be recovered in an advantageous modification of the process.

It follows that post-fermentation is only a step in the process for forming CO2.

The alcohol reduction stage need not necessarily be followed by post-fermentation. It may instead be carried out after filtration, in the storage or filtering celler. A carbonising step is then necessary, to form CO2.

In this modification of the process a normal, aged diet beer may be taken as the starting product, and a low-carbohydrate, aicohol-reduced and calorie-reduced beer made from it, so that changing requirements can easily be met even within one day.

A particularly surprising discovery has been that even beers from retailers can be processed according to the invention to form utilisable alcohol-reduced beers, and that this can even be done bv an economical process. It should be noted, however, that the lower limit for alcohol reduction is 2% if it is not to destroy the flavour structure.

The quality of the beer is known to be impoverished by the removal of alcohol. Taking the quality of a normal beer as a basis, worts are prepared from normal raw material, and their composition is such that normal fermentation produces beers where the colloidal and flavour structure is harmoniously balanced.

The flavour, by which is meant the total sensory impression given by a beer, of course also carries the impression of the ethanol. If some or all of this taste substance is removed, the flavour and particularly the full-bodied-character of the beer will naturally be changed. A reduction in the full-bodied character in turn leads to a change in the impression left by bitter substances. With the reduction in ethanol by-products of fermentation are of course also removed, and their absence may cause a void in the aroma. The preparation of alcohol reduced diet beers by the removal of alcohol is therefore equivalent to squaring a circle. Contrary.

to AT-PS 264427 it has been found, surprisingly, that the froth containing the important aromatic and wort substances need not be separated in a first stage of the treatment, and need not be fed to the vacuum evaporator in order to avoid any change in the substances. Instead, the reduction in the fuil-bodied character and aroma of diet beers caused by alcohol reduction can largely be compensated for relative to prior art, by following the method of the invention. The alcohol reduced beer prepared according to the invention may also be blended with a non-alcohol reduced diet beer in known manner.

The various embodiments of the method of the invention may be selected at will by the brewer, according to what specific advantage of the particular embodiment is most important to him. If he is starting with a beer from a retailer, water should be removed from this thinner beer, thereby concentrating it and giving it improved flavour.

If the brewer chooses an embodiment where the separation of alcohol is interpolated before a second phase of the main fermentation or, with single phase main fermentation, before a post-fermenting stage, this will encourage decomposition of the dextrins during the second fermentation, since the alcohol content is reduced. The separation of alcohol is more favourable economically when it takes place during or after a main fermentation step. If the separation of alcohol takes place in the fermentation celler when the main fermentation step is over, a normal, aged diet beer may be used as the starting product. It will then be treated according to the invention, to make a low-carbohydrate, alcohol-reduced and calorie-reduced beer, so that changing requirements can easily be met even within one day.

In a particularly advantageous embodiment of the invention malt extract and/or diastase solution is concentrated in a thin-layer evaporator. This further accelerates the process known from DE-PS 20 52 963.

Concentration of the diastase solution in the thin-layer evaporator accelerates the decomposition of the dextrin, with a very gentle action.

The process of the present invention will be further explained with reference to the accompanying drawing. This consists of one figure, which is a flow diagram of the process of this invention in a preferred form.

Beer is fed into a thin-layer evaporator through the pump 1 and distributed over a rotating conical surface by a nozzle. Centrifugal force causes the beer to spread out over the heating surfaces in a very thin turbulent layer. Alcohol is evaporated out of the beer in contact times of less than one second. The concentrate is conveyed out of the thin-layer evaporator, through a skimmer tube to a plate-type cooler 5 by means of a pump 4. Downstream of the cooler is a carbonising unit (not shown) which feeds carbon dioxide back into the completely decarbonised beer. The vapours containing alcohol are condensed in a spiral condenser 6.

The condensate is sucked up by a pump 7, and the non-condensed gases by a vacuum pump 8. The steam used for heating is kept at constant pressure by a regulating valve 9 and passes through a lateral pipe connection into a base plate of the installation. The condensate formed on the heating surface is thrown by centrifugal force onto the outer surface of the cone and sucked up by means of a vacuum pump 8. The control vacuum for the steam regulating valve 9 is generated by the vacuum pump. The pipe for the control vacuum 13 is connected to the regulating valve 9. References 11 and 12 denote the inlet and outlet for the cooling water at the plate-type heat exchanger 5, condenser 6 and vacuum pump 8 with sliding ring sealing.

Where the heating steam is at a pressure of over 1 bar, a three-way tap 1 4.must be adjusted to allow the condensate to flow off through a discharge pipe 10.

The process of this invention may be applied to beers of different strengths, e.g. so-called low strength beers, i.e. brewed from a wort having a low original wort strength of from 7-8%, medium beers, i.e. brewed from worts having an original wort strength of from 11-14%, or strong beers brewed from worts having an original wort strength of from 16-20%. In the case of the medium and strong beers, however, dilution with oxygen-free water is required before or after the thin layer evaporation. Intermediate strength beers (e.g. 9 or 15%) may also be treated in the same way.

Comparative Test In a comparative test a diet beer (Beer A) made in accordance with DE-PS 2,052,963 was compared with a diet beer (Beer B) made in accordance with the present invention. The two beers were tasted by a panel of observers and the various taste characteristics of the beers compared. The results are tabulated below: A 0 B X t-value Purity of smell 1 3.1 8 3.4 6 296** Purity of taste 1 2.8 10 3.4 4 3.69** Intensity of bitter 5 3.5 4 3.5 6 0.32 component Goodness of bitter 3 3.0 5 3.2 7 1.28 component Fully body 2 3.4 3 3.2 10 0.43 Sharpness 3 3.4 2 3.4 10 0.43 Goodness 1 2.6 12 34 2 3.99** Preferred 1 - 13** 1 Correctly assigned 13 Wrongly assigned 12 Key: A = number of observers preferring characteristic quality in preference to beer B.

B = number of observers preferring characteristic quality in preference to beer A.

= = average points value (point scale 1-5) X = number of observers expressing no preference for either beer A or beer B t-value = a statistically based evaluation which indicates whether the two beers are distinguishable in respect of the quality criterion assessed. One * indicates basically a statistical certainty of assessor evaluation of 95%, two ** 99% and three *** 99.9%.

The taste test shows that beer B was judged, with statistical certainty of 99%, better in purity of smell, purity of taste and goodness. The other criteria of quality do not differ. This shows that diet beer prepared in accordance with the present invention is better in quality than the compared beer.

Claims (12)

1. A method for the preparation of a low-carbohydrate, alcohol-reduced, low-calorie diet beer, which comprises reducing the alcohol content of a brewed beer by evaporation under vacuum, characterised in that the alcohol content of the beer is reduced by evaporation in a thin-layer evaporator at a temperature up to about 30-50"C over a period of from 1 to 10 seconds, with the proviso that where the starting material is a beer brewed from a wort having an original wort content in excess of 8%, then the beer is diluted with oxygen-free water either before or after said evaporation.

2. A method according to claim 1, wherein said evaporation takes place at about 50"C.

3. A method according to claim 1, wherein said evaporation takes place at about 30"C.

4. A method according to claim 1, 2 or 3, wherein the alcohol reduction takes place during the primary fermentation of the beer on a slip stream withdrawn from the primary fermentation zone.

5. A method according to claim 1,2 or 3, wherein the alcohol reduction takes place before a post-fermentation stage when CO2 is formed.

6. A method according to claim 5, wherein the alcohol reduction takes place before a second phase of a two-phase main fermentation process.

7. A method according to claim 1,2 or 3, wherein the alcohol reduction takes place after fermentation has terminated and the alcohol-reduced beer is then recarbonised.

8. A method according to any one of claims 1 to 7, wherein alcohol reduction takes place under a vacuum of 0.04 bar.

9. A method according to any one of claims 1 to 8, wherein the by-products of fermentation are recovered from the alcohol distillate by means of a rectifying column and are recycled to the alcohol-reduced beer.

10. A method according to any one of claims 1 to 9, wherein the product alcohol-reduced beer is blended with a non-alcohol reduced diet beer.

11. A method of brewing a beer which comprises fermenting a wort in such a way that dextrins in the wort are converted in the wort to fermentable carbohydrates by adding a diastase solution thereto, the carbohydrates in the wort being fermented comprising at least 0.75 gms of carbohydrate per 100 ml of beer, characterised in that the beer is subjected to alcohol reduction by a method claimed in any one of the preceding claims.

12. A method according to claim 11, characterised in that the diastase solution is concentrated in a thin-layer evaporator before being added to the wort.