DE1642772A1 - Method and device for improving the taste of fermented beverages - Google Patents

Description

The invention relates to a method and a device for improving the taste of fermented beverages, such as Beer, fruit wine and wine, by removing the hydrogen sulfide formed during fermentation.

Hydrogen sulfide is a normal product of metabolism. During the fermentation of beverages, like beer, it is made from cysteine by desulphurisation and from inorganic sulphate by reduction and probably also formed from other precursors. It is known to brewers that beer, and especially freshly fermented beer, for this reason it often contains so much hydrogen sulfide that its taste and especially its aroma are serious is affected. This applies to both bottom-fermented beers (Polsner and lager types) and top-fermented beers Beers (ale and stout types).

109823 / Π299

This hydrogen sulfide can be produced during the maturation of the beer disappear, a process that essentially arises from a slow secondary fermentation, with the hydrogen sulfide is expelled from the beer by the slowly developing carbon dioxide. In practice it turns out however often that for some reason the finished beer still contains a noticeable concentration of hydrogen sulfide, in particular, in the case of Pilsner-type beers, this residual hydrogen sulfide may be sufficient to maintain the fineness affect their taste

The concentration of hydrogen sulfide in finished beers can vary from imperceptible traces up to about 0.06 ppm. His presence is already at a concentration of about 0.005 ppm noticeable; at this concentration he is as this is hardly noticeable, but rather as a modification of the general beer aroma. At 0.005-0, Q2 will be ppm Odor described as "fierce" or "sulphurous" i.e. more or less abnormal and undesirable. At about 0.05 ppm it is because of the characteristic smell of hydrogen sulfide recognizable. While such low concentrations of hydrogen sulfide, for example below 0.005 ppm in beer, not detrimental, and may even add a desirable element to its flavor, are higher than concentrations these are definitely undesirable and perceived as a disadvantage. Accordingly, one method of eliminating Hydrogen sulfide from beer or its reduction an imperceptible concentration, a process that can help reduce the economically expensive secondary fermentation to be abbreviated, highly desired.

BAD ORIGINAL 109823/0299

»642772

The extremely low solubility product of copper sulphide suggests that it could be a very simple means in this regard to meter small amounts of, for example, copper sulphate into the beer in order to precipitate all hydrogen sulphide in the form of copper sulphide, which is then produced during regular beer filtration before bottling is removed on bottles. However, the fact that beer normally contains traces of % copper on the order of 0.1 ppm or more, which is usually more than equivalent to the amount of hydrogen sulfide to be removed without such removal actually occurring, suggests that it does Problem is not quite as simple as it may seem at first glance. It is true that adding an excess of copper sulphate to the beer, on the order of 1 ppm copper, actually removes any perceptible hydrogen sulphide therefrom, but the relatively high concentration of residual copper remaining in the beer is such a technical disadvantage that it does Procedure for practical use not seriously be liable recommended g. The disadvantage associated with soluble copper in beer is that it drastically reduces the stability (shelf life) of the beer; Copper accelerates the precipitation of proteinaceous material from the beer, making it cloudy and unsaleable. The small amount of copper that is normally present in beer is probably already bound to proteinaceous material in the beer in a complex, so that it is not available for the precipitation of hydrogen sulphide. Likewise

must have the excess amount of copper sulfate that is necessary to eliminate hydrogen sulfide from beer, is largely attributed to copper, the is bound immediately complex, with only a small amount for the reaction with the hydrogen sulfide for Available.

The new invention consists in metering suitable small amounts of copper into beer by means of electrolytic dissolution. Experiments have shown that this process removes the hydrogen sulfide from beer can without causing a significant increase in its copper content.

According to the invention, beer becomes in the course of its guidance to the filter between two electrodes made of electrolytic copper or between two electrodes, one of which, the anode, is made of electrolytic copper. By applying a suitable electromotive force along the Electrodes, copper goes into solution in the beer. The concentration of the so dissolved copper depends only on

a) the amount of electricity conducted through the beer (measured by the product of amperage and time) and

b) the speed at which the beer flows past the electrodes.

'The copper dissolution can therefore be precisely regulated by the Amperage · is regulated in relation to the beer speed.

109823/0799

As an example, some results are cited that start with a small laboratory prototype apparatus. Electrolytic copper electrodes with a

ο
1.9 cm effective area and 1.2 cm apart are mounted on plastic sealing rings on each side of an electrolytic cell constructed from Perspex. By applying CO pressure, the beer to be treated is made to _{flow past these electrodes at a speed of 3 tons of} O4 ml per second. The application \ an electromotive force of about 1.5 volts results by the flowing beer a stream of 36O microamps. From Faraday's second law of electrolysis it follows that this current strength and the beer speed cause the dissolution of 0.039 mg of copper per liter of beer. From the standpoint of beer stability, this copper concentration is completely insignificant, yet it is sufficient to remove all or most of the observable hydrogen sulfide from the beer, as shown below (in fact, 0.039 ppm copper is equivalent to 0.021 ppm hydrogen sulfide). Subsequent return analyzes of the unfiltered beer on copper confirm that the metered amount of copper in the beer does not exceed the calculated from current and speed quantity of beer within the experimental error limits g (+ 0.006 ppm). Similar analyzes carried out on the filtered beer (subjected to sterilization filtration to remove fine particles) show an even lower proportion of copper, which is consistent with the view that some or all of the electrolytically dosed copper has been converted to copper sulfide, which is through the filtration has been removed.

109823/0 2 99

ib42772

Two approaches are cited to show the effectiveness of this procedure in removing hydrogen sulfide from beer. In the first approach, a previous dosage of small amounts of sodium sulphide is added to beers in order to increase their hydrogen sulphide content to a concentration which is somewhat higher than is likely to be found in practice. A portion of each of these beers is then electrolytically treated with copper in the manner just described, using the Heat as a reference sample. Samples of the reference beer and the same beer that has been electrolytically treated are then presented in pairs and distributed in a random manner to a group of experienced tasters. The panelists, previously instructed on the difference to look for between the samples in each pair, are asked to indicate which portion of each "pair has been treated for hydrogen sulfide removal after their assessment. Of 55 assessments made by If up to 5 tasters were given to Ik different pairs of beer samples, 49 judgments were correct, 2 were wrong, while the remaining k judgments did not differentiate between the samples. According to standard statistical tables for evaluating the significance of such tasting tests, there is an overwhelming probability (statistical significance , or greater than 99.95 ^ probability) that the electrolytic treatment actually produced the intended effect.

The second set of experiments was more rigorous in that beers were produced without any prior addition of sodium sulfide to artificially increase their hydrogen sulfide concentration, have been used. That was the case with several of these beers

1 09823/0299.

The presence of hydrogen sulfide, even for a sharp nose, has only been dubiously proven. Of 63 assessments made by the same 5 tasters on 28 samples of commercially available beers, k5 judgments were correct, 10 were incorrect, and 8 were indeterminate. Even if the extent of the differentiation was less than in the first approach, as was to be expected, the result nevertheless retains static significance, since it shows that the electrolytic treatment M certainly leads to an improvement in the beer.

In order to determine the effectiveness of the electrolytic treatment in removing noticeable hydrogen sulfide from beer, taste tests are preferred over chemical analyzes for the following reasons. On the one hand, taste tests are more relevant, since they are essentially identical to the type of assessment that is actually made by the beer consumer. Second The chemical method used heretofore for determining traces of hydrogen sulfide in beer has been shown to be unreliable, especially when the ones to be analyzed Beers contain varying concentrations of copper. f

Since the hydrogen sulfide in beer cannot be determined directly with sufficient accuracy, the effect is of the copper electrolysis on the sulphide content has been determined indirectly by collecting the copper sulphide formed during the electrolysis on filters and the increase of whose copper content is determined. To this end, will

109823 / Π299

1b42772

a small excess of hydrogen sulfide in the test beers added before electrolysis to ensure that the electrolytically added copper is enough material found in order to react with it. The following table shows the amounts of electrolytically added copper (precisely calculated from measurements of the amperage and time) and the amounts of copper obtained by analysis on the Filters have been obtained (all numbers are ppm in beer).

attempt electrolytic
added
copper on the filters
won
copper % Recovery 1 1.08 1.01 93 2 10.6 0.89 84 3 1, ^ 3 1.33 93 4th 0.88 0.86 98 5 0.96 0.66 69 6th 0.98 0.67 68 7th 1.26 0.96 76 8th 0.97 0.87 90 9 0.47 - 0.30 64 10 0.53 0.72 136

0.96

0.83

87+ 7.

Almost all of the copper added by electrolysis reacts with the hydrogen sulfide present in the beer, so that

109823 / n? 99

Electrolysis, provided it is not excessive, will not result in any appreciable increase in the copper content of the beer should. This is electrolyzed by copper analysis Beers and comparative beers have been confirmed in practical brewing tests. The average difference of the Copper content between such pairs is 0.03+.

0.03 ppm, an amount that is neither statistical nor in the

Practice matters. ^

For the practical treatment of beers, the process presented here has the significant advantage that it simply by regulating the current strength above or below can be adjusted down to any concentration of hydrogen sulfide that may be present in the beer to have grown without the final copper content of the beer is noticeably increased and thus without impairment »A stability.

An electrolytic cell for practical use has to be capable of the required amount of copper Sieren in the beer to do- *, which flows past the electrodes at a rate of, for example, 1 or 2 liters per second (36 to 72 hectoliters per hour). It has been found empirically that this can be achieved by increasing the area of the electrodes to about 200 cm (with a distance of about 2.5 cm between them) and increasing the electromotive force between the electrodes to about 5 volts. Electrolytic treatment of a flowing electrolyte, in this case beer, appears to be more effective than that of a static electrolyte. This can be partly due to a

10 9 8 2 3/0299 ORIGINAL INSPECTED

unexpected decrease in the electrical resistance of the Electrolytes, as the electromotive force applied increases, are based, and in part on a continuous one Removal of the electrical double layer by the fast-flowing electrolyte.

One embodiment of an electrolytic cell is shown in FIG reproduced in the accompanying drawing. Mean:

Fig. 1 is a front view of the cell, partly in section

and
Fig. 2 is a plan view, also partially in section.

The entire housing of the cell is made of stainless steel. The cell contains 2 circular electrodes 5 "made of electrolytic copper are worked. For example, for brewery use, the electrodes can be 16 cm in diameter and 0.6 cm thick be with a central hub for making the electrical connections. The electrodes 5 are supported by disks 6 made of stainless steel, against which they are isolated by the rubber disks 7, held in place with a Distance of, for example, 2.5 cm. These stainless steel disks 6 are in turn threaded by and grooved rings 8 which can be easily unscrewed for cleaning and replacement of the electrodes, firmly .-- held in place. The entry and exit openings 9 and 10 of the electrode housing are conical outwards in a plane parallel to the electrodes and inwards in a plane perpendicular to them, in such a way, that an approximately constant cross-sectional area through the

109823/029 9.

ORIGINAL INSPECTED

1b42772

Passage of the cell is observed. The whole inner ' The surface of the housing made of stainless steel together with the inlet and outlet openings is covered with an insulating layer of synthetic resin coated «known as Teflon (registered trademark) in order to prevent any of the applied current from being diverted through the housing.

Electricity from the normal 220 volt AC power source will be ™

expediently applied to the electrodes by means of a compilation, which have a continuously variable transformer, rectifier and an ammeter (0 to 1 A, graduated in divisions of 0.02A) to regulate the copper dosage. It can easily be determined from a table showing the current required to achieve any desired copper dosage at any given beer speed to surrender.

It is desirable to provide for the same consumption of material by each of the two electrodes by the direction of current at regular intervals, for example once the g day, by hand, or automatically switched at shorter intervals. In doing so, about 300,000 to 4,000,000 hl of beer can be treated before the electrodes are reduced to half their original thickness. The resulting reduction in mechanical strength is irrelevant, since the stainless steel support disks themselves are designed to withstand the internal pressure. The very slowly increasing distance between the electrode surfaces as their material is consumed has no effect on that

109873 / Π 299

1b42772

Functioning of the cell and can only be noticed at the very gradual increase in the voltage required to maintain a given current through the cell, because of the increasing thickness and the increasing electrical resistance of the beer layer.

Electrolytic dosing of copper can be carried out on beer that has matured in the conventional manner has been, i.e. by means of a slow secondary fermentation, however, or of course, before the final filtration of the beer, or it can be used in conjunction with an abbreviation of the Secondary fermentation can be applied. This shortening the The duration of the secondary fermentation, if carried out under conventional conditions, need not be too drastic because in this case the maturation of the beer can be found to be unsatisfactory in other respects. To get out of the Removal of hydrogen sulfide according to the invention To obtain maximum benefit, this removal can be used in conjunction with manufacturing methods in which the maturation of the beer can be accelerated in other respects by processes that in one way or another Way different from the traditional way of working.

As an example of the effectiveness of the electrolytic treatment of traditionally matured beer tl'rotzdem a significant portion of hydrogen sulphide has retained in its aroma and taste, following brewing attempt is quoted as saying. A quantity of about 60 hl of beer is passed through the electrolyte cell, through which an electric current is placed that is sufficient to produce a dosage of 0-3 ppm copper, and the beer is filtered

1098? 3 / n? 99

Jb42772

and bottled. Next, the power to the cell is switched off and another 60 hl of untreated beer is filtered and bottled as above. This electrolyzed beer and the reference beer are then sent to a group of taste experts and ^{assessed using the known "triangle taste test method 11.} Of 76 triangles presented to the group, 48 correctly identified the individual sample, ie it determined

gave itself the statistical meaning that the beers differ in taste from one another. Of the 48 correct triangles, 39 showed a preference for the electrolyzed beer and 9 a preference for the control sample. So there was a preference, again XXX

of importance for the electrolytically treated beer before, because of the absence of hydrogen sulfide, however no significant preference for the untreated beer at all.

If, as mentioned above, the slow secondary fermentation is to be accelerated, this must be performed in particular in such a manner g, that the removal of possibly present diacetyl (formed as a byproduct during the primary fermentation) is achieved in a shorter time. This can be achieved by performing the secondary fermentation at a temperature range higher than that used in the conventional slow secondary fermentation. According to the invention, the temperature during the secondary fermentation can therefore be in the range from about 4 to 8 ° C. Furthermore, a relatively high yeast concentration is used, for example about 10,000,000 to 20,000,000 cells per ml. Under these conditions, the

109823/0299

Secondary fermentation around 1 week instead of the conventional one Allowed to progress for 6 to 10 weeks. This way of working accelerates the maturation of the beer in every respect the exception that the remaining hydrogen sulfide is more appears than would otherwise be the case. However, this can be done by the electrolytic process be eliminated.

Preferably in connection with the acceleration of the secondary fermentation, the two-yeast system is used, that is, in the primary fermentation, the wort to be fermented is divided into two parts, for example having the same volume, and one of which, A, with a flaky strain of pure yeast is fermented while the other part, B _{1, is} fermented with a non-flaky strain. At the end of these two primary fermentations, the yeast has settled in A before fermentation is complete, while B is completely or almost completely fermented, with a lot of yeast still remaining in suspension.

To be used for the purpose of carrying out the secondary fermentation the two fermented wort A and B mixed together in the storage tanks, with the yeast transferred from B the Fermentation of the remaining unfermented sugar in A continues. If necessary, more non-flaky yeast can be added to bring its concentration down to that mentioned above Bringing concentration suitable for accelerated fermentation. After several days of under these conditions of relatively strong secondary fermentation, im generally in 4 to 12 days, the beer should be matured «

109823/0299.

(and especially free of diacetyl aroma and taste), although there may be too much residual hydrogen sulfide. The beer is therefore cooled, for example to about 0 C and left to stand at this temperature for a few days so that the yeast can settle. It is then subjected to the electrolytic process described before the final filtration in order to remove the residual hydrogen sulfide. This is how a matured beer becomes _Λ

Manufactured in a much shorter time than conventionaltlxche ™

Procedure.

For example, a beer that has undergone accelerated secondary fermentation in the brewery and then electrolytically treated prior to filtering and bottling is compared with normal beer from the same brewery, i.e. that has undergone conventional secondary fermentation without subsequent electrolytic treatment. Of 68 triangular taste tests of these two products, only 25 correctly indicate the individual sample, which shows that there is no statistically significant difference in taste between them. This is confirmed by the reasonable ä added favors: 12 for the accelerated ripening with subsequent electrolytic treatment and 13 for the conventional beer. Since none of these preferences achieve statistical significance, it can be concluded that the accelerated process in combination with the electrolytic treatment results in a beer which is not inferior in taste to a beer produced by the conventional process.

109a? 3 / ■ η? QQ

Brewery attempts at electrolytic treatment on a total of 6 beers (carried out in k different breweries), all of which had undesirably high hydrogen sulfide concentrations, had the following overall result:

Out of 1018 triangular taste tests between treated Beers and comparative beers have 4? 6 correctly the individual

XXX

standing sample, i.e. it gives the statistical meaning that the beers differ in taste from one another differentiate. Of the 476 correct triangles, 283 show a preference for the electrolytically treated beers (Meaning) and 193 'a preference for the comparison samples (no meaning). The usefulness of the electrolytic Treatment in improving the beer taste has thus been empirically proven.

Copper analyzes of the electrolytically treated beers show an average value of 0.20 ppm copper, while the untreated comparison beers give 0.17 ppm. The difference between these values, 0.03 ppm, also has a standard error of + ^ 0.03 so that it is actually statistically irrelevant. In agreement with this result, measurements of the stability of these beers show that the electrolytic treatment has no influence whatsoever, neither on their cloudiness in the cool state nor on their permanent cloudiness. Likewise, their foam stability was completely unaffected by the electrolytic treatment.

Claims (1)

-17-Fat claims A method for improving the taste of fermented beverages by removing hydrogen sulfide formed during fermentation, characterized in that at least a part of the hydrogen sulfide is precipitated by electrolytically dissolving a small amount of copper in the fermented beverage. 2. The method according to claim 1, characterized in that the drink is continuously conducts between two electrodes, at least one of which is made of electrolytic copper, with a direct current of variable strength by means of the electrodes passed through the drink and the current strength in relation to the speed of the beverage flowing through the gap between the electrodes is regulated 3. Method according to claim 1 or 2, characterized in that the beverage is beer . k. Method according to Claim 3 »characterized in that the copper is dissolved after the beer has been helped, but before the final filtration. 109823/0299 5. Method according to claim 3 or 4, characterized in that g e k e η η draws that the beer before the electrolytic dissolution of the copper in an accelerated ripening is subjected. 6. The method according to claim 51, characterized in that the accelerated ripening consists in a second fermentation at a temperature between k and 8 ° C. 7 · The method according to claim 5 »characterized in that the accelerated ripening under Use of the two-yeast system is carried out. 8. Methods of improving the taste of beer, essentially as described above described. 9 · Drinks with improved taste, made according to the method according to claims 1 to 8. BATH ORIGINAL TO9823 / 029 9