DE2745829A1 - PROCESS FOR MANUFACTURING SUITABLE ISO ALPHA ACIDS FOR BEER MANUFACTURING - Google Patents

Description

FROM KREISLER SCHÖNWALD MEYER EISHOLD FUES FROM KREISLER KELLER SELTING

PATENT LAWYERS Dr.-Ing. by Kreisler f 1973

Dr.-Ing. K. Schönwald, Cologne Dr.-Ing. Th. Meyer, Cologne Dr.-Incj. K. W. Eishold, Bad Soden Dr. J. F. Fues, Cologne Dipl.-Chem. Ali.'k from Kreisler, Cologne Dipl.-Chem. Carola Keller, Cologne Dipl.-Ing. G. Selling, Cologne

Ke / To.

5 COLOGNE If 11 October 1977

DtIUlMANNHAUS AM HAUP1DAHNHOF

BREWING PATENTS LIMITED, Portman Square, London, WIH OBB (Great Britain)

Process for the production of iso-C-acids suitable for beer production

609816/0769

; 02 21) 23 45 41-4 · Tele «: 888 5307 dopa d ■ Telrgromm: Dompatenl Cologne

Process for the production of iso-o {acids suitable for beer production

The invention relates to the production of iso-Ct acids, which are suitable for beer production using OC acids extracted from hops.

Usually a wide variety of components are extracted from the hops and used instead of the hops themselves in the production of beer. The most important constituents that have so far been extracted in this way are the resins and in particular the ⁰ ^ acid fraction of the soft resins, which are produced by chemical

10 see rearrangement being converted into iso-CC acids, which are the main bitter components of beer. The particular advantage of extracting the

Ct acids consists in the fact that these with essential higher efficiency than this

15 was possible in the usual beer production.

In traditional beer production, only 25 to 35% of the CK acids in hops are used. By extraction of the OC-acids, their isomerization separated from the beer and the addition of the iso-CX-acids to the

20 beer after fermentation it is possible to get higher

Use amounts of OC acids, 60 to 85%. Another major advantage with regard to the use of extracts is that they can be used for longer periods of time Can be stored for a period of time without the presumed

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borrowed oxidative degradation in particular the main ones Bitter substances including the Ct acids in hops long storage occurs.

The usual methods of extracting the hops include the use of organic solvents a, such as methylene chloride, trichlorethylene, hexane and / or methanol. However, these solvents dissolve not only the desired OT acids, but also relatively large amounts of ß-acids, tannins and chlorophyll and various other hop ingredients.

A primary extract of hops with an organic solvent has the following composition:

Wt%

'* -Acids ß-acids not more precisely

identified

Soft resins

Hard resins hop oil

8 8

3 2

45 tannins
20 chlorophyll

8 10

1 - 5

Fats and waxes 1-2 resins in total 15-60

Wt%

0.5-5 1

Dust (cell fragments) 2-5

inorganic

Salts 0.5 - 1

Solvent residues
(mostly CH ₃ Cl ₂
or CH ₃ -OH) 1.5-2.2

Water 1-15

To high quality ^ acids suitable for isomerization suitable to obtain, the crude extract must comparatively often with other organic solvents cleaned, and numerous and often complex process steps must be applied. Furthermore it is difficult to completely remove the organic solvent from the extract; because in technology and in trade Usual extracts can contain more than 1% by weight of solvent.

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keep. While it is believed that residual solvents, particularly those based on methylene chloride and methanol, are mostly lost during the production of beer, one cannot completely rely on that during the production such accidental removal of potentially harmful materials from a foodstuff actually takes place. Furthermore, although there are currently no major technical difficulties, to meet the requirements of the health authorities with regard to the content of residual solvents, considerable difficulties arise in the future.

An organic solvent extract that has been purified in order to be isomerized to produce a for the bittering of beer suitable iso-o (.- acid suitable to be, would have the following typical composition:

Weight -% Tannins approx Wt% 0.5 - 1 ^ Acids 60 - 80 Chlorophyll approx . 0.1 ; to 10 ß-acids 0.3 - 0.5 dust . 0.1 not more precise
identified
Soft resins 1 - 2 inorganic
Salts no Hard resins 1 - 5 Solvent-
leftovers *) essentially
chen none Hop oil up to 1 water Fats and waxes approx. 0, 1 until Total resins 70 - 90

♦)

In addition to CH ₃ Cl ₂ and CH ₃ OH, which are usually used for both extraction and purification, these residual solvents can contain other solvents such as ethyl acetate, butanol and trichlorethylene.

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Carbon dioxide fluid, either in the form of a liquid or as a supercritical gas, has been proposed as an extractant for hops. For example, GB-PS 1 388 581 describes a process for producing a hops extract by extracting hops with various gases in the supercritical stage with regard to temperature and pressure. Carbon dioxide is said to be the most preferred gas. Extraction with carbon dioxide under these supercritical conditions leads specifically to an olive-green pas.ten-shaped product that contains d -acids, ß-acids, soft resins, hard resins and small amounts of tannins that cannot be precisely identified. The extraction conditions can be varied so that yields of i ^ acids are obtained which are comparatively higher than the concentrations in the starting hops, but the best extracts described contain only about one third of the c ^ acids. Optimal extraction conditions are considered to be those in which the extraction is carried out under a pressure substantially above the critical pressure, which for carbon dioxide is approximately 72.8 atmospheres, preferably above 100 atmospheres and at temperatures of 40 ° to 50 ° C. It is stated that with a suitable selection of the extraction conditions it is possible to extract essentially all soft resins and almost all hop oil while reducing the extraction of the hard resins or the corresponding extraction of the β-acids can be reduced at the expense of the increase in the amount of the extracted hard resins. It is further stated that it is possible to extract hops with liquid carbon dioxide, but this does not form part of the invention of this known method because "its dissolving power is less than the solvency of supercritical CO-".

The extract described in GB-PS 1 388 581 is quite comparable with typical primary extracts that are listed under

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Use of organic solvents are available and appear suitable to use in beer production to be found, for example with the addition of copper. However, the extract described is for isomerization Not suitable without careful cleaning, in which components are removed that are under typical Isomerization conditions would cause an adverse taste and also lead to the formation of significant Quantities of turbidity when added to the beer. (In practice it is not possible to do a cleaning after isomerization because the mixture is more complex than the impure extract.) Im present Taking this stage of the extraction technique would require the use of organic solvents while abandoning the main benefits of using supercritical carbon dioxide in the extraction of Hop.

Liquid carbon dioxide is described as an extraction medium for hops in the USSR Author's Certificate No. 167798 by Pekhov, Ponamarenko and Prokopchuk and by Pekhov in Masloboino-Zhirovanaya Promyshlemnost Vol. 34, Part 10 (1968) pages 26 to 29. The _{product obtained during the extraction of the hops with liquid CO 2} at 20 ° to 25 C is of the Author described as a slightly brown viscous mass. Shafton and Naboka (iSU Sev-Kauk Nauchn Tsentra UGssh Shk, Ser Tekh Nauk 1975, 3 (3), 29-31 / Chem Abs Vol. 84 (1976) 120046a 7J describe CO ^ extracts of hops as complex mixtures of X-, ß- and \ 'acids, o (-, ß- and \? -soft resins and hard resins, which decompose quickly, especially as a result of rather rapid auto-oxidation during storage. The purity and stability of such CO ₂ extracts on the whole is not secured, although it is possible to use them in beer making if copper is added, but it is obvious that they are not

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can be isomerized to form an iso-oC acid without extensive purification, and in any case they are less stable on storage than conventional hop extracts obtained using organic solvents. So far it has not yet been established that a primary extract can be obtained from hops which would be suitable for direct isomerization with the formation of an iso _v X acid suitable for bittering beer. The present invention is based on the knowledge that the extraction of hops with. liquid carbon dioxide, ie under subcritical conditions, can be carried out to obtain a primary extract which can be isomerized successfully without prior purification.

The object of the present invention was to provide an improved process for the production of iso-o (. -Acid preparations which are suitable for addition to beer, and in particular for the production of high quality preparations which are suitable for are suitable for adding to light beer after filtering.

The solution to this problem is a process for the production of iso- «X acids, which is characterized in that the hops are brought into contact with liquid carbon dioxide at a temperature not below -5 ° C and at least some of the • X-acids transferred into the liquid carbon dioxide, a primary hop extract high purity from the liquid carbon dioxide isolated and contained in the hops extract, ^ (- isomerized acids in iso- ^f a acids.

The highly pure primary isolated as an intermediate when carrying out the process according to the invention Hop extract always contains <\ -acids, ß-acids, hop oil, mostly small amounts of water and generally at most traces of the organic solvents in primary extracts

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Main impurities contained in solvents, namely soft resins, hard resins, and tannins which are not defined in detail and chlorophyll.

Table 1 shows the purity of the primary extract, represented by the amount of impurities that interfere with the subsequent isomerization. Column A gives the maximum permissible amount of the above impurities, which have proven to be a major disruption to the subsequent isomerization _r Column B gives the expected maximum values of the impurities extracted with liquid carbon dioxide under the general conditions given here, and column C gives the values that are achieved according to the invention should.

Table 1

pollution Amount in% by weight, based on the extract not closer de
finished soft
resins
Hard resins
Tannins
Chlorophyll
Fats and waxes
dust
inorganic salts 3
0.5
0.5
0.2
0.2
0.5
0.5 B. C. A. all in all 4% 0.1
0.1
0.1
0.1
0.1
not before
act
0.1 (2)
<0.1
not available
the
Il
Il
<0.1 ⁽²⁾
not available
the
-0.1 ⁽²⁾ 0.3 0.1

(D

(2)

The analytical method used will be explained later.

These values show that in some primary extracts the impurities qualitatively with the analytical

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"1

method could just be determined, but that the values were so low that they could be with sufficient Accuracy could be specified. The numbers given as maximum values represent the limit of analysis; the actual amount of impurities can also be smaller.

The main components of the primary extract are as above indicated, oC ~ acids, ß-acids and hop oil and in the extract contained in the following quantities:

Weight -% (3) oil acids 40 - 75 ß-acids 20 - 40 Total resins 70 - 98 (3) Hop oil up to 10 water up to 5

These figures are the result of analyzes carried out with respect to the resins according to the published in Analytica EBC in Swiss Brewery Rundschau, 3rd Edition, 1975, page E49 described method and in relation on the other components, in particular the tannins and chlorophyll according to that of J. Jerumanis in Bulletin Association Anciens Etudiants Brasserie Louvain, 1969, Volume 65, Page 113 Method have been carried out.

The upper analysis values for o ^ acids and hop oil are generally only achieved with a hop containing unusually high proportions of these materials holds, more common upper limit values are around 65% for Ct acids and around 3% for hop oil.

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A primary extract of high purity is to be understood as meaning an extract in which the undesired Impurities according to Table 1 are present in amounts that are lower than those in column A of Table 1 reproduced. Under the conditions given here, under which hops with liquid carbon dioxide has been extracted, results have been obtained that are much better than the maximum values of column A.

In practice, the composition of the extract can be given as follows:

Wt%

■ ^ acids 40-75, mostly 40-65

ß-acids 20 - 40, mostly 25 - 35

Total resins 70 - 95, mostly 80 - 95

15 hop oil up to 10, mostly up to 3

Water typically 2-5

and essentially no organic contaminants derived from hops.

The amount of water in the extract is not critical per se, but as will be explained below, lead to substantial Amounts of water in the carbon dioxide during extraction mean that tannins are extracted from the hops. It appears that when essentially dry liquid carbon dioxide is used, the amount of water in the extract depends on the amount present in the hops and thus receives amounts of water under certain circumstances that are outside the specified range, while the above figures are to be regarded as typical are.

The high quality primary extract has the golden yellow color of the <"\ acids and is usually at ambient temperature a solid or semi-solid crystalline

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Material, the consistency of which depends on the particular extraction conditions and the type of hops extracted. Another mark of purity is that typical primary extracts reveal identifiable crystals of X- and ß-acids upon cooling Separate approx. 4 C. Conventional primary extracts obtained with solvents show no evidence of such Crystallization.

It can be seen that this primary extract is a much purer material than primary extracts with typical organic solvents and especially with regard to hard resins and soft resin components which are not defined in more detail is substantially purer than purified extracts obtained with common organic solvents.

A fundamental difference is that those obtained using liquid carbon dioxide Extracts contain essentially more β-acids than purified extracts obtained in the usual way. It seems that the much larger amounts of the ß-acids with respect to those present in another relation extraordinary cleanliness and purity of the extract can be tolerated. As a result, the high affects Content of ß-acids the favorable isomerization of the X-acids does not occur in the production of an iso- > (.- acid preparation, and the ß-acids can be from one such preparation can be separated by filtration at a suitable pH.

According to our opinion, this has not yet been reported, but has been published in publications of the prior art instead the maximum tolerable amount in extracts to be isomerized ß-acids indicated very low, namely less than

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-, if

1 %. It is believed that according to the invention o (-acids can be isomerized because of the proportion of the other materials that can interfere with isomerization is so low.

The general physical conditions with regard to temperature and pressure during the extraction are up to critical to the invention to some extent. If the extraction is carried out at temperatures below -5 ° C, so there is a tendency to extract unwanted organic compounds. These connections seem to be mainly fats and waxes, but at lower temperatures larger amounts of hard resins and probably extracted tannins. At subcritical temperatures above -5 ° C, on the other hand, extracts become higher Maintain purity. The extraction temperature is subcritical because, as from GB-PS 1,388,581 shows the use of supercritical temperatures in the extraction of substantial quantities of hard resins, Chlorophyll, tannins, etc. leads.

Good results can be obtained within this temperature range, but it is generally preferred not to use temperatures too close to the critical temperature in order to eliminate the possibility of the carbon dioxide accidentally becoming supercritical. The generally preferred temperature comprises the range from -5 ° to +20 ⁰ C.

The pressure at which the extraction is carried out must of course be sufficient to remove the carbon dioxide to keep liquid, but not so high that the carbon dioxide corresponds to the supercritical fluid behaves as described in GB-PS 1,388,581. In general, it is both convenient and preferred under the vapor pressure of liquid carbon dioxide

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the extraction temperature to work. To small temperature differences to enable between the different parts of the extraction apparatus, in particular, when temperatures below ambient are used in the extraction, and to continue within To allow hydrostatic pressure differentials in the apparatus, the pressure should usually be slightly above the Vapor pressure, for example, up to 10% above the vapor pressure. The change in vapor pressure of liquid Carbon dioxide with temperature is shown in Table 2.

Table 2 Vapor pressure
Atm.
(absolutely) temperature
⁰ C ) 72.8 31 (critical temp. 71, 2 30th 56.5 20th 44.4 10 34.4 0 30.1 -5

From a technical point of view, it is desirable to keep the pressure as low as possible and the temperature as close as possible to keep at ambient temperature as much as possible. These requirements are not exactly compatible with one another, and In practice, there is usually a compromise that affects these considerations as well as the speed of the extraction, the selectivity and purity of the extract takes into account the optimal process temperature for each

Identify 30 specific case.

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The form in which the hops are extracted is not particularly critical as efficient extractions are carried out can be made with fresh or dry hops, hop cones, ground, powdered, pellets shaped hops or coarsely chopped hop pellets.

However, since the bulk density of the hop cones is very low, it is also used for practical reasons during the extraction Hops used in powder or pellet form. Hop powder appears for extraction according to the invention

10 to be suitable, and the further editing that

Requiring hop pellets should not provide any particular advantages in extraction. The optimal extraction conditions may vary depending on the particular shape, but the choice is the exact one

15 Optimal Conditions a matter of simple chemical engineering.

Of course, the hops themselves should be of suitably high quality. Inferior or spoiled hops cannot provide suitable extracts. The special kind or culture of the hops used seems to be for the Extraction itself does not have to be essential, and both germinated and non-germinated hops can be successful extracted. The specific composition of the extract and the yield obtained is a function the extracted hop culture and depending on whether the hops have germinated or not (seeded or seedless). Satisfactory extracts were obtained from the following hop cultures: Wye Northdown, Wye Saxon, Northern Brewer, Wye Challenger, Bullion, Comet, Pride

30 of Ringwood and Styrian Golding.

The amount of liquid carbon dioxide needed to extract the hops appears to be a function of solubility of the acids in carbon dioxide, the type of extraction

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systems and the exact conditions that apply. The limits of solubility of the ^ Acids in liquid carbon dioxide are not yet determined, but experimentally there was no difficulty in achieving concentrations of 3.7 g / l, and higher concentrations should be possible. The extraction efficiency in terms of both the proportion of extracted CX acids as well as those for The amount of carbon dioxide required increases with the increase in the effective contact time between the extraction Carbon dioxide and the hops. This can be achieved, for example, by simply circulating the carbon dioxide through an extraction layer. Also, this can be achieved using a semi-continuous or continuous extraction processes, for example using countercurrent technology. Although it is desirable to increase the actual contact time between the liquid carbon dioxide and the hops it has been found that essentially complete extraction in the laboratory can be achieved at times which are comparable to contact times for the usual extractions with commercially available solvents come into use. It can be assumed that liquid carbon dioxide is actually the hops in the Extracts much faster than common organic solvents, and not just specifically for the relatively small number of experiments carried out to date is true with the relative and absolute ones the small apparatus used for the extraction

30 limited throughput.

The degree of extraction of the <X acids is a function of the precise method used. More than 90% of the υ (acids present were successfully extracted without difficulty, and it can be assumed that even higher extraction yields are possible without great difficulty.

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The extracted θ {acids can easily be removed from the liquid Carbon dioxide extract can be obtained by "boiling off" the carbon dioxide as a gas. This can be more appropriate Alternatively by heating the solution under constant pressure so that the liquid carbon dioxide boils. This is equivalent to isothermal conditions. Alternatively, the evaporation of the gaseous CO_ can be carried out by Pressure reduction or relaxation take place, i.e. approximately adiabatically. Both methods are on a small scale suitable without affecting the quality of the product. However, it is preferred, especially at industrial implementation, the carbon dioxide is recovered in order to condense it again and again as Use extraction liquid. It is lighter and more thermodynamically effective and therefore also more economical, to carry out this cycle under almost constant pressure, in order to achieve the low to use specific heat and the latent heat of vaporization of the carbon dioxide in order to achieve the necessary change in state to reach. In this regard, adiabatic evaporation is due to the large pressure and pressure Temperature changes less preferred.

The extract by heating the liquid carbon dioxide to vaporize it, isolated, it is expedient to secure a heating source of moderately high temperature, for example 30 ° to 40 ⁰ C to be used by a corresponding heat transfer. In addition, since the extract tends to become quite viscous and begins to crystallize out even at lower temperatures, for example below about 5 ° C., it is therefore advisable to isolate the extract close to or slightly above ambient temperature in order to eliminate these special problems.

The primary extract of hops obtained in this way

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is an essentially pure mixture of X acids and ß-acids together with part of the essential oil (hop oil) contained in hops, but in general without hard resins, chlorophyll or tannins. There was no difficulty in isolating crude extracts, which were essentially free of hard resins, chlorophyll, tannins, etc. This purity of the product is a considerable advantage over the products made according to the previously described hop extraction methods were obtained. A quantitative examination of the crude product showed that there was a higher proportion in the product of χ acids versus ß acids is present than solely on the basis of the relative ratio of -_ \ - and ß-acids in the hops were to be expected. The degree this selectivity is considerably higher than that described in GB-PS 1,388,581, but there is no explanation why the conditions used according to the invention for the extraction both in this respect as well as in other aspects of purity

20 are particularly advantageous.

As has already been stated above, according to the invention The primary extract obtained is usually a mixture of <·; < Acids, ß-acids and at least a certain part of the essential oils of hops.

The mixture usually contains moisture, but this is not considered an impurity in terms of further processing is considered, although it may be convenient and / or desirable to dry the extract, if it is to be stored for a long period of time.

The extract of high purity is colored yellow, i.e. it has the color of the o (, ~ acids, and is not green, brown or darkened in some other way, as is customary with primary extracts obtained by known processes of hops including the extract described in GB-PS 1,388,581. The extract is solid,

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a viscous paste or liquid, the exact shape largely depending on the temperature.

The extract contains certain amounts of hop oil and since this can be a valuable product in itself it can be separated from the primary extract by steam distillation under vacuum, for example under the general temperature and pressure conditions given in US Pat. No. 3,979,527. The separation can therefore expediently be carried out in such a way that the extract is mixed with water and this mixture is distilled under vacuum at a temperature of less than 50.degree. C., preferably between 20.degree. And 25.degree. The distillate, an emulsion of hop oil in water, can be collected as a dispersion in ice by ^{cooling the steam below 0 C, more usually to -20 0} C or below. The hop oil separated from the extract in this way can be used to impart the aroma and taste of the hops to the beer. It has been found, however, that when liquid CO 2 is used, essentially all of the hop oil is removed from the hops, so that, as explained in the above description, it must be ensured that only the desired fraction is separated off in the steam distillation described. Furthermore, it appears that some of the more volatile components of the hop oil are _{extracted very quickly by the liquid CO 2} and are lost without due care, even during the time when the remaining air is escaping from the extraction apparatus. For these purposes, when hop oil is desired as a particular product, the hop oil is preferably extracted _{from the hops prior to extraction with the liquid CO 2.} In any case, it is likely that the liquid CO 2 extract will contain at least some hop oil components. Since some components of the hop oil can be decomposed during the isomerization and the taste and aroma are unfavorable

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influence, it will generally be desirable to remove the hop oil from the extract.

As indicated in US Pat. No. 3,979,527, the amounts of hop oil which are normally desired in beer in order to impart this taste and aroma to the extent that is the case with dry hops are in the range between 0.5 and 2 ppm. The amount of hop oil in CO ₂ -Primärextrakt is usually such that, when the entire hop oil remaining therein, the added beer amount of ⁰ C- acid preparation is present oil using the iso- as the final product in substantial excess over that what is desired to give the beer a hop aroma and taste. This will especially be the case if the extracted hop variety is a variety with a high proportion of available hop oil. It is therefore desirable to remove at least sufficient amounts of hop oil to prevent this from becoming a serious problem.

Another practical point in favor of separating the hop oil before use to obtain the sort ^ acid is that a brewer in general preferred to use substantially pure materials. He therefore wishes that according to the invention obtained iso -? (- acid preparation to use and also Hop oil isolated from the primary extract, he will prefer to use these materials separately available as a previously prepared but unseparated mixture.

It is not necessary for the preferred isomerization process, which is described in more detail below and in fact, it is also not preferred to specifically remove the hop oil from the extract prior to isomerization. However, if desired, use the extract as it is

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clean, the entire hop oil can be cleaned by steam distillation removed. However, care should be taken to avoid excessive heating, as this can reduce or destroy the bitter value of the extract. This degradation can be avoided by carrying out the steam distillation at a suitable reduced pressure, for example so that the temperature does not exceed 50 ° C.

In connection with the purity of the extract, it has been found that the extract readily complexes with a number of metals such as iron and copper. Accordingly, if the liquid CO ₂ containing the extract is passed through mild steel or copper pipes, in particular in the presence of moisture, this leads to iron or copper being leached out of the pipe walls. This is undesirable because it can cause corrosion problems and the crystallization of salts in the extraction apparatus, especially with copper, which forms blue crystalline salts with the soft resin acids and contaminates the product with heavy metals. Although iron is not as toxic as copper, it is undesirable because other heavy metals, which can be toxic, are carried by the iron and the presence of iron in the extract appears to reduce the stability of the product, particularly with regard to oxidative degradation. Extracts contaminated with iron are more typically brown than yellow in color. The problem of contamination by metals can be countered by using a suitable inert material for or for cladding the extraction device. It has been found that this problem can be solved by fundamentally making the extraction device out of stainless steel, using glass for visible parts and suitable inert plastics. Other materials can undoubtedly also

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Find use and the selection of suitable inert Materials is in common chemical engineering knowledge.

As mentioned briefly above, the quality of the extract can be impaired if there is excess water is present in the carbon dioxide used as the extraction liquid, in particular insofar as Tannins, which are comparatively soluble in water, due to the dragged along with the liquid carbon dioxide Water can be extracted. Commercial grade liquid C0 "as used in the UK by the Distillers Company (Carbon Dioxide) Limited is a high quality product whose water content is in the parts per million range (typically about 20 ppm). Such a carbon dioxide is sufficiently dry to be used in the present invention. The purity of such a liquid CO is within the relevant British Standard (BS No. 4105/1967). A liquid carbon dioxide, which conforms to this British Standard is of sufficient purity for the purposes of the invention. Using a less pure liquid carbon dioxide can cause quality problems of the extract.

The possibility of heavy metal contamination and the pressure of water and / or other contaminants in the Liquid carbon dioxide can, according to our opinion, be at least partially responsible for the Failures of the prior art proposals for extracting hops with liquid carbon dioxide, to obtain a product whose purity approximates that of the primary extract of the present invention is.

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The isomerization step of the process according to the invention can be carried out in any suitable manner. However, some procedures, such as The process of photoisomerization may require purification of the extract prior to isomerization do. Even if such purifications are comparative in the high purity extracts obtained according to the invention can be carried out easily, this means a further step that is not necessary if the preferred isomerization method is used. Other methods often include the use organic solvent and are therefore not preferred. Organic solvents are preferred Isomerization process not necessary.

The preferred method is to isomerize the acids by heating, preferably by boiling an aqueous solution of the extract that has been made alkaline. It is typical to dissolve the extract in alkali, for example in sodium and / or potassium hydroxide or preferably carbonate, preferably to obtain a solution with a pH value of 8 to 11. For solutions that do not require subsequent dilution (see below) require, the concentration of s ( acids is typically 0.5 to 5 g / l, and the concentration of sodium and / or potassium carbonate is in the range of 0.01 to 0.5n. The solution is then heated to the boil, for example 5 minutes to 2 hours in order to isomerize the G \ -acids to iso-u (-acids. During the boiling hop oil is driven off with the steam. It is known that the alkali isomerization of the O (-acids in relatively concentrated Solutions can be carried out, for example up to about 35% by weight oC acids. Such high concentrations can be used in the isomerization step according to the invention if desired. The use of high concentrations can

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be advantageous in order to reduce the requirements with regard to heating during the isomerization and subsequent cooling, and thus the total amount of alkali required to maintain the desired pH value of 8 to 11 is somewhat less than is necessary for more dilute solutions. This last point can be important, since a reduction in the content of inorganic material reduces the likelihood of inorganic salts crystallizing out, namely of KCl or NaCl, if the iso - (\ - acid preparation finally present is considerably concentrated, for example to 30 to 40 The concentration of the X- acids during the isomerization is accordingly not restricted according to the invention, and concentrations of up to 400 g / l are envisaged.The specifically chosen concentration is a matter of choice depending on the particular circumstances and the person skilled in the art will certainly not have serious difficulties in this regard, typical concentrations are in the range between 0.5 and 300 g / l, usually between 3 and 100 g / l.

The solution is then cooled, preferably to at least ambient temperature and more preferably to temperatures between 0 ° and 10 ⁰ C. The solution is then acidified, for example to a pH value between 2.5 and 5, preferably 3.5 to 4, 5 and particularly preferably to about 4. This can be done in a suitable manner by adding a suitable amount of acid, such as, for example, hydrochloric acid. At this acidic pH, the ß-acids are much less soluble than the iso - ^ - acids, they are precipitated and can be removed, for example by filtration or centrifugation. If the isomerization was carried out with a relatively concentrated solution of X-acids, then, because the solubility of the iso- o (-acids in the

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Precipitation of the P-acids set acidic pH values is quite low, the isomerized alkaline extract solution must be diluted before acidification in order to prevent an undesired loss of iso - '. χ -acids. Accordingly, at the optimal acidic pH of about 4, at which iso- <N-acids are soluble to about 0.5% by weight (approx. 5 g / l), and with more concentrated alkaline isomerization solutions, these should be soluble before acidification be diluted in order to prevent the precipitation and the possible loss of iso ( -acids. The preferred concentration of iso-o (-acids in this stage depends on the pH value, it is generally in the range between 0, 5 and 5 g / l and preferably between 3 and 5 g / l.

The solution is expediently filtered with a filter aid such as, for example, kieselguhr. After filtering the iso-extract can be added directly to the beer, as described in more detail below, in order to make it to bitter. However, the iso-extract is not very stable in storage at acidic pH values and therefore it is especially if the extract is not added directly to the beer, preferably the pH value is moderately alkaline set, for example to a pH of 8 to 10, preferably to about 9, by adding a suitable alkali, for example sodium and / or potassium hydroxide and / or carbonate, and the solution to concentrate to a desired level, usually 10 to 40% iso-o (-acids.

It has been found that when the isomerization is carried out quickly, a small proportion of the Hop oil is not boiled with the steam. If the complete removal of the hop oil is desired, so this can be achieved by continuously boiling the alkaline mixture. However, the iso-extract will concentrated before use as below

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described, it was found that any remaining hop oil can easily be removed with the water which is evaporated from the iso-extract.

The concentration can be carried out in order to obtain solid crystalline iso- · Λ -acids in the form of the corresponding alkali metal salts, if desired. Since iso-o (-acids can be lost through decomposition as a result of overheating, in particular during concentration through evaporation, it is preferred that during the evaporation the solution is ^{heated to no more than 50 ° C. and preferably to no more than 40 °} C. Experimental It has been shown that there are no difficulties with evaporation at 35 ° C. Rapid evaporation, if necessary, can be carried out under a partial vacuum. Concentrations of 10 to 40% by weight / volume are generally suitable for storage and transportation, and the step of basifying the iso-extract solution after or during the concentration, provided that there is no unnecessary delay, can be performed if desired , take place.

Use of the preferred isomerization technique is particularly advantageous because it enables the implementation of the method according to the invention in a particularly elegant way. In a very particularly preferred direction, the invention thus consists in one Process for obtaining an isomerized hop extract, this process comprising the following stages includes:

1) Extracting the hops, preferably in the form of crushed pellets, with liquid CO ₂ at a temperature from -5 C to 30 ⁰ C, preferably from -5 to

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27A5829

-, 27 -

20 ⁰ C and under a pressure which is slightly higher than the corresponding vapor pressure of the liquid CO ₂ at the extraction temperature;

2) Obtaining a hops primary extract of high purity by evaporating the liquid CO ₂ ;

3) Preparation of an alkaline aqueous solution without further purification, which preferably contains the extract in an amount corresponding to 1 to 100 g / l o (-acids and sodium and / or potassium carbonate, preferably in a concentration of 0.01 to 0.5n, this solution preferably having a pH of 8 to 11;

4) Boil this solution, preferably for a period of 5 minutes to 2 hours, for essentially all to convert the ° ^ -acids present in it into iso- ° (-acids and to remove hop oil components;

5) cooling the solution, preferably to a temperature of 0 ° to 10 ° C;

6) Dilution, if necessary, of the alkaline solution to a concentration of no more than about 5 g / L Iso-CC acids and adjustment of the pH value of the solution to about 2 to 5, preferably to about 4.0 by adding acid;

7) Filter the acidified solution to precipitate

to remove ß-acids, while the iso-Ci-acids in Solution remain; and if necessary

8) Concentration of the solution of the iso-OC acids thus obtained to a predetermined level by evaporation, preferably at a temperature of not

30 more than 40 ° C and

9) Adjust the pH of the filtered solution either before, during or after concentrating to a pH value between 8 and 10, preferably of about 9.0, by adding alkali.

The produced by the method according to the invention

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as

The isomerized extract is of excellent quality and can be obtained in high yield. It was possible to extract 85 to 95% of the <Λ -acids of the hops without any significant difficulty, and it can be expected that even higher extraction values are possible. Typically up to about 70% of the ß-acids were extracted. Although the contents of the soft resin acids of different hop species vary, no difficulties have been found experimentally in extracting a number of different hop cultures, as stated above.

The conversion of the C ( -acids of the extract to iso-3 (-acids can be carried out essentially quantitatively by means of the preferred isomerization process according to the invention, with filtration losses for the purpose of removing the β-acids being low. Losses during evaporation are generally not of This is important, provided that the temperature is kept below about 40 ^° C. In this way, the effective yield in the process according to the invention can typically be 90% and higher yields can certainly be achieved without major difficulties.

It is an extraordinary advantage of iso- <X-acid preparations, which are obtained according to the process of the invention that they are not measurable when added to the beer Cause turbidity. This allows particularly favorable comparisons with isomerized extracts that are im Are commercially available. The isomerized product according to the invention is of a sufficiently high quality so that it can be added to light beer after filtering without significant cloudiness. This is before was practically impossible; even the best isomers on the market had to go to the last filtration to be admitted in the end because of their tendency to be a

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Cause turbidity. The actual utilization of the bitter value of the hops was thereby reduced. With Commercially available isomerized extracts are the achievable utilization of the under normal conditions Bitter value between 70 and 75%, while the maximum under carefully controlled and optimal conditions is about 85%; with non-isomerized extracts added to the brew kettle is an exploitation the bitter value is typically between 27 and 35% compared to around 25 to 30% if the hops are without Extraction is used. Passed according to the invention no major difficulties in achieving utilization values of more than 80% without particularly optimal ones Conditions, and it is believed that values of 90% and more can be achieved by the methods of Addition to be designed more optimally.

When commercially available isomerized extracts are used to bitter the beer, sometimes results Overflow problems. The substances that mainly promote overflow are ■ oxidation products of the hop resins contained in the hops and / or formed during processing. Another Advantage of the process according to the invention is that the isomerized extracts obtained are not

25 show a tendency for overflow as such

Substances are neither extracted from the hops nor formed during processing.

The quality of the iso-d -acid preparations according to the invention have been confirmed by analyzes. In the case of Otter, Silvester, and Taylor, J. Inst. Brew. 78

(1972) 57, described tests by means of column chromatography showed typical tests prepared as described above Samples the presence of iso-CC acids, however neither c (-acids, ß-acids nor humulin-

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acids noted. These components are generally detectable in thin-layer chromatography. Commercially available iso-extracts generally show much higher levels of these undesirable compounds. The iso- o (-acids according to the invention also contain no detectable amounts of polyphenolic compounds. These are usually commercially available Extracts exist and are known to cause the poor properties of the materials viewed, especially with regard to the formation of a haze.

The invention is explained in more detail below in connection with the drawings. Here shows

1 shows an apparatus for the discontinuous extraction of hops with liquid carbon dioxide,

2 schematically shows an apparatus for the semi-continuous extraction of hops with liquid carbon dioxide, and

3 schematically shows an apparatus for converting a primary extract into an IsO- (X-acid preparation which is suitable for adding to beer.

According to Fig. 1, the hops 1 is contained in a pressure chamber 2 which has an inlet 3 with it in connection standing tap 4, an outlet 5 which includes a sintered metal filter 6 and equipped with a tap 7 is, as well as an observation window 8 and a pressure gauge 9. To extract the hops, the cock 7 is closed and liquid CO- is introduced into the pressure chamber 2 via the inlet 3 and the cock 4. The tap 4 is closed and the chamber 2 is shaken to close the hops and the liquid CO

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3Ζ

mix and extract the soft resins (CL acids and ß acids) into the liquid CO _2. When the extraction is complete, the extract can be transferred to a second pressure chamber 10, which has a piston 11 and an enclosed observation window 8 and is connected to a suction line 12 equipped with a heater 13 and a tap 14. To transfer the extract, the tap 14 is closed and the tap 7 opened, whereupon the extract overflows through the filter 6, which retains any dust carried by the extract, into the flask 11 in the chamber 10. Then the cock 7 is closed. This extraction and transfer process can be repeated if necessary or desired to extract the hops. The extract can be separated from the liquid CO by opening the tap 14, this controllably leaving the chamber 10, escaping into the atmosphere via the heater 13.

According to FIG. 2, liquid CO ₂ in the storage tank 20 is pumped through the heat exchanger 23 by means of the pump 21 at a pressure measured by the pressure gauge 22, in which the temperature of the liquid CO _{2 is set} to the temperature desired for the extraction. In a commercially available extractor, the storage

25 tank 20 normally to a temperature between

-15 and -20 ° C cooled. For extractions on a smaller scale, the storage tank can expediently be replaced by a number of gas bottles for liquid carbon dioxide, which are arranged in parallel. If CO ₂ gas cylinders are used, they are usually not particularly cooled and have an internal pressure at ambient temperature that is greater than the vapor pressure of the liquid CO 2 at the extraction temperature, and this excess pressure in the gas cylinders can be used to generate the liquid _{CO 2.} through the system with a suitable flow

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to drive speed, so that the need for a pump is eliminated.

For practical reasons it is advisable to adjust the temperature of the liquid CO- at the outlet of the heat exchanger 2 in order to allow any temperature differences between the ambient temperature and the actual extraction temperature. It is believed that the extraction in the flask 11 is generally carried out at a temperature below ambient rather than at a temperature above ambient, so that the liquid CO _{2 is} thereby cooled to compensate for the absorption of heat from the environment Ambient temperature and can be up to 20 ° C warmer than the liquid CO ₂ in the extraction column. In order to reduce such undesired heat transfers to the liquid CO ₂ , the extraction column and the pipeline valves etc. connected to it are generally covered in order to ensure a suitable degree of thermal insulation. In a suitably insulated column, the liquid CO ₂ usually does not need to be more than about 2 or 3 C cooler than the desired extraction temperature. It has been found that about 3 C is generally a suitable value in extraction apparatus for small-scale extractions, where problems with regard to heat absorption occur much more easily than in industrial plants with comparatively larger surface areas.

From the heat exchanger 23, the liquid CO ₂ passes the extraction column 24, which contains hops in a suitable form, for example as a powder or as crushed pellets. In the apparatus shown, the column is arranged vertically and the liquid CO ^ flows upward through the column.

809816/0769

Although only one extraction column is shown in FIG. 2, others can be arranged in parallel thereto, for example between B and B ¹ . By directing the flow of the CO ~ through a large number of columns (the necessary taps, etc. are not shown), it is possible to operate the apparatus semi-continuously, for example by separating columns containing exhausted hops from the pressure circuit in order to keep them with refill fresh hops while the extraction continues in the other columns, which makes it possible to obtain extracts continuously.

From the top of the extraction column, the liquid C0 ~ containing the extract is passed to an evaporator 2 5, where the (Χ> 2 is driven off through line 28. The The evaporator is heated, for example by warm water entering at 27a and exiting at 27b. The water can expediently be 40 C warm, although the temperature of the heating medium to a certain extent of the extraction temperature depends and is chosen so that an adequate heat transfer is ensured and the separation of the extract is prevented at a temperature which is so low that the extract is produced very viscous or solid, or so high that the extract is degraded or decomposed. The extract that is typically a liquid at the contact temperature in the evaporator is, is collected in the evaporator or in a collecting container connected to it and may from time to time Time to be drained through the cock 26.

30 The gaseous carbon dioxide that makes the evaporator 2 5

leaves through the outlet 28, is passed through the condenser 29, in which the gaseous CO- to Reliquefaction is cooled. The liquid CO- is then led to the storage tank 20, from where it is used as a liquid

809816/0769

total CO _{2 is} pumped via the pump 21 to the heat exchanger 23 and in this way circulates through the column 24 to the evaporator 25. Fresh liquid CO ₂ can be introduced into the circuit through valve 30 _{to replace lost CO 2} when the extract is withdrawn via valve 26 or when the extraction columns are refilled.

In Fig. 2 it is shown that the liquid CO ₂ flows through the extraction column 24 rising upwards. While the upward _{flow of the liquid CO 2 is} preferred for technical reasons, it is also possible, if desired, _{to let the liquid CO 2} flow down through an extraction column containing hops.

Other forms of apparatus can also be used to _{carry out the extraction with liquid CO 2} , and the extraction steps according to the invention are not limited by the particular form of apparatus in which the extraction is carried out.

In Fig. 3, a high quality hops primary extract 40 in liquid CO ₂ , for example the product prepared using the apparatus of Fig , 5n are brought together in a vessel 42 which is equipped with a heating coil 43 and a condenser 44. The solution of the hop extract in alkali, which typically contains 0.5 to 2 g / lc (acids at a pH value of 8 to 11, is boiled for 5 minutes to 2 hours, for example, in order to isolate the <* acids in the extract -c (-acids. The vapor escapes during this boil and carries away hop oil that was present in the primary extract. Water vapor and hop oil are condensed in condenser 44 and can be collected at 45.

809816/0769

3t

After the isomerization has ended, the alkaline solution is drained from the vessel 42 via the valve 46 and passes through the cooler 47, where the solution is preferably cooled to 0 to 10 ° C. After cooling, the solution 48 is transferred to the vessel 49, which is equipped with the stirrer 52 and the pH meter 51. The acid 50, for example hydrochloric acid of suitable concentration, is introduced into the kettle 49 in order to acidify the isomerized extract, for example to a pH of 2.5 to 5. The acidic mixture is stirred and the β-acids are precipitated. The mixture, which optionally contains a filter aid, such as for example kieselguhr, is then passed through the filter or centrifuge 54 via the valve 53. The filtered or centrifuged solution 55 is then transferred to the vessel 56 which is equipped with the stirrer 59 and the pH meter 58. Alkali 57, for example sodium and / or potassium hydroxide and / or carbonate, is introduced into the vessel 56 in order to make the solution of the iso- (X -acids alkaline, for example up to a pH value of 8 to 10. This alkaline Solution is then passed through valve 60 to concentrator 61, which is suitably a flash evaporator equipped with heating coil 62, vapor collecting vessel 63, vacuum pump 64 and condensate collector 65. The temperature inside the evaporator is preferably no more than 40 ⁰ C to prevent the iso- °> - acids from breaking down. The concentrated iso-OC acid preparation can be removed from the collector 65 via the valve

30 to 66 can be deducted.

Although the apparatus shown in FIG. 3 is the production of a concentrated iso-acid preparation describes, can, if so desired, be preferred, the isomerized oC ~ acid solution from a deduct earlier production stage, for example

809816/0769

after the filter 54 or optionally on the valve Furthermore, although the apparatus is related has been described with a discontinuous procedure, possible continuous or semi-continuous Procedure to carry out.

The construction of the individual parts of the plant for use in such an apparatus is simple; suitable, if perhaps not optimal, plants are readily available. Indeed Continuous processes require the construction of special plants, but the construction of such also prepares them Systems for those skilled in the field of chemical engineering no major difficulties.

The invention is further illustrated by the following examples.

example 1

Discontinuous extraction of hops and conversion into an isomerized extract

100 g of powdered Wye North Down-hops with 7.3% oC-acids was extracted in the A-paratur shown in Fig. 1, with 1.0 1 of liquid CO ₂ into the to the inlet 3 and the thereby associated valve 4 equipped chamber 2 was introduced under a pressure of 51.1 atmospheres. At this pressure, the temperature inside the chamber was about 16 C. The chamber was shaken for 15 minutes, during which the pressure rose to 52.2 atmospheres. The cock 7 was then opened and the liquid was transferred through the sintered filter 6 into the piston 11 which stood in the second pressure chamber 10. The cock 7 was closed and the cock 14 opened, whereupon the liquid carbon dioxide evaporated and released as a gas into the atmosphere over a period of 45 minutes.

809816/0769

was left. The hops were extracted a further 7 times in the same way, and the extracts, the remaining Solid C0 ~ were collected. The piston was then removed from the pressure chamber, and the remaining solid carbon dioxide was evaporated, namely through a Bunsen valve, with a yellow viscous Extract remained in an amount of 15.8 g.

The extract was analyzed by thin layer chromatography using the method described by US Pat European Brewery Convention (J. Inst. Brewing 1970, 76, 386). It was just the presence of o (-acids and ß-acids found in the form of two separate spots when the plate was treated with ferric chloride reagent was sprayed. When products made by extraction of hops with organic solvents obtained in this way, the chromatogram is usually complex and frequently exhibits more than 10 spots.

The extract had a content of 40.7% f \ acids, determined by a conductometric method using methanolic lead acetate (J. Inst. Brewing 1970, 76, 343). Thus 88.1% of the available CC acids were extracted from the hops using liquid CO ₂ . Examination of the extract by column chromatography on Sephadex (J. Inst. Brewing, 1972, 78, 57) showed that 70.2% of the β-acids present in the hops had been extracted.

A 10.0 g sample of the extract was steam distilled according to the method described by Howard (J. Inst. Brewing, 1970, 76, 381) and a total of 450 mg of hop oil was isolated. In this attempt 83% of the available oil had been extracted from the hops by the liquid carbon dioxide.

809816/0769

Similar yields of oil and resins were obtained when powdered Wye-Challenger hops were made according to this procedure using liquid C0 _? was extracted. This solvent was used to extract the whole Wye Challenger type hop cones and also cones that had not yet dried, i.e. green hops. Hop resins and oils were successfully extracted from these samples.

A 1.1 g sample of the extract obtained from the Wye-Northdown hops and containing 40.7% <i-acids was placed in a flask equipped with a condenser via a coobation attachment. 500 ml 0.1 η sodium carbonate were added and the mixture was boiled for 15 minutes under a nitrogen atmosphere. The hop oil was separated off and the mixture was ^{cooled to about 0 °} C. and the pH was adjusted to 4.0 by adding 2N hydrochloric acid. The mixture was stirred at constant pH for 1 hour, then 10 g of kieselguhr was added and a stream of nitrogen was passed through the mixture for 5 minutes to encourage flocculation of the "{acids g) filtered and washed with water, the filtrate and washing liquid were combined, whereupon the pH of the solution was adjusted to a pH of 9.0 by adding 2N potassium carbonate to give a dilute solution of the desired isomerized extract Qualitative examination of the extract by thin-layer chromatography showed the presence of iso-o (-acids together with only trace amounts of; X-acids and ß-acids. A quantitative analysis of this extract using the method of Otter et al (J.Inst. Brewing, 1972, 78, 57) showed that the yield of iso-oC acids obtained from the hop extract was 79.9%

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were 70.4% of the available ^ C acids in the Wye-Northdown hops were converted into iso-acids.

The extract was reduced to 15% iso-Cv acids (weight / Volume) using a rotary evaporator (temperature 35 ° C, 15 mm / Hg) without loss of iso-CC acids concentrated.

Example 2

Production of an isomerized extract (semi-continuous hop extraction)

200 g of powdered Northern Brewer hops containing 6.1% ^ -acids were placed in the column of the semi-continuous extractor shown in FIG. Liquid CO ₂ was circulated through the system for 5 hours at a pressure of 62.3 to 63.7 atmospheres. The pressure in the system was then released and the extract that had collected in the evaporator (temperature 40 ° C.) was removed.

Another five 200 g samples of the hops were extracted in the same manner, and those from the six extractions obtained extracts were collected (157.8 g). The extract was prepared using those described in Example 1 Method investigated, whereby the following results were obtained!

a) Only CX acids and ß acids could be used in thin-layer chromatography be found, b) 93% of the available α-acids and 60% of the available ß-acids had been extracted by the liquid CO.

c) 70% of the available hop oil was present in the extract.

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- JkG -

¥ 4

28.0 g of the hop extract, which contained 43% Cl acids, was described in the same manner as in Example 1, isomerized and after filtration through kieselguhr a yield of 98% iso-ov acids was obtained. Only trace amounts of c (- and ß-acids were in the extract established.

The volume of the aqueous iso-extract with a pH of 4 (8.2 l) was reduced to below 11 by evaporation at 50 ° C./15 mmHg. The -pH-value was then adjusted with 0.2N sodium carbonate solution at 9 and the volume to 1 1 filled in recovering the isomerized extract as a pale yellow solution (total yield ^iso-r v-acids 88%, ie 1.06% w / v ).

The addition was made to an unhopped beer Add the isomerized extract (diluted to 0.50% weight / volume iso - ^ - acids) before bottling on kegs in an amount of 30 mg iso-QC acids / 1 beer. The bitterness of the beer obtained, determined by the recommended analytical method (J.Inst. Brew., 1971, 77, 181) was 26 EBU. The use of iso-OC acids in beer was thus 86%.

The iscmerized extract was also added to a light beer in the tank before bottling in a quantity of 42 mg iso-oC acids / 1 beer was added. The bitter one of the bottled beer, determined as indicated above, was 35 EBU. The utilization of iso-OC acids in beer was thus 83%.

A commercially available isomerized hop extract was another batch of the same light beer in the tank with the same dilution and in the same Amount added as in the case of the above

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Iso extract was done. The initial turbidity values of the bottled beers, determined according to the recommended ones Analysis method (J.Inst. Brew., 1971, 77, 181) amounted to 0.60 EBC units with the one with the iso-extract of this Example of bitter beer and 4.42 EBC units for the beer that isomerized to that commercially available Contained hops extract. The turbidity value of the beer bittered with the iso-extract of this example did not exceed 105 EBC units with a storage time of 15 weeks. A beer is said to be sufficiently stable in storage with regard to the formation of turbidity, if the turbidity values after storage for 12 weeks are not be more than 205 EBC units. Induced overflow tests were performed on bottled beers according to the procedure by Laws and McGuinness (J. Inst. Brewing, 19 72, 78, 303) with the observed beer loss in the case of the beer with the iso-extract prepared according to this example was 0.4 g / 0.284 1 and in the case of Beer with the commercially available isomerized hop extract 117.4 g / 0.284 1. In comparison, lost a traditionally brewed bottled beer, i.e. in which no extract or iso-extract is added after brewing 0.5 to 5 g / 0.284 l (1/2 pint) under appropriate conditions.

The beer bittered with the new isomerized extract shows no tendency to overflow.

Example 3

Semi-continuous extraction of hops on a semi-industrial scale

30 830 g powdered Wye Northdown hops containing 7.1%

Containing OC acids was added to the column of the semi-continuous Extraction apparatus according to FIG. 2 entered. Liquid CO ~ was in the system with a Speed of 6.4 liters per hour and a pressure of

809816/0789

60.9 atm circulated for 5 hours. The pressure in the system was then reduced using the vent valve relaxed, and the extract (114.8 g) that had been collected in the evaporator, using the in the method described in Example 1 isomerized. The analysis of the product showed that the overall achievable Efficiency of the extraction of the et-acids and isomerization was 88%.

Example 4

Samples of different hop cultures were _{extracted with liquid CO 2} and isomerized according to the method described in Example 2. The extracts and isomerized extracts were of comparable high purity. The results of the extractions and isomerizations are shown in Table 3, while Table 4 shows the results of tests with regard to turbidity, overflow, bitterness and utilization of these isomerized extracts when they were added to a beer.

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Tabel

hop
Culture Extra
tion time
(Hours.) extract
yield
(% By weight,
based
on hops) '^ -Acids-
Amount in
extract
(%) extracted from the hops
Components (%) ß-acids Hop oil yield
in the
Isomerisa
tion (%) Total yield
of iso-CC acids
(%) Northern
Brewer 5 13.2 46.0 cC acids 87 67 97.4 93.5 Comet 3 13.8 39.9 96 60 71 70.0 66.5 Wye
Northdown 2 15.4 43.5 95 81 83 79.9 73.5 Wye
Target 1 13.8 54 92 56 86 95.1 77 81

cn cc is?

Table 4

Hop culture added
Iso- ο. Acids
(ppm) Cloudiness
(EBC units after
Encore (4)
induced
Outflow
(Beer loss) Bitter
(EBU
Units) Exploitation
(%) Northern
Brewer 24.5 original
lich 0.55 no 21.4 87.3 Comet 24.8 0.52 0.52 no 20.5 82.7 in trade he
more stable
Eso extract A 25.3 0.52 3.8 69.7 19.1 75.4 in trade he
more stable
Iso extract B 25.0 0.52 4.1 78.2 18.9 75.7 Control ⁽⁵⁾
attempt - 0.52 - 0.5 - - 0.52

Loss of weight for bottles containing 278 ml of beer unhopped beer

cn oo

CO

Hi

Empty soap

Claims (7)

Claims 1. Process for the preparation of iso-o (-acids, thereby characterized in that one hops with liquid carbon dioxide at a temperature not below -5 ° C and at the same time at least some of the egg acids contained in the hops are released into the carbon dioxide transferred, a primary hop extract of high purity isolated from the liquid carbon dioxide and the cA acids contained in the hop extract in IsocX. -Aids isomerized. 2. The method according to claim 1, characterized in that the extraction of the hops with the liquid carbon dioxide in the temperature range between -5 ° C and +20 ⁰ C is carried out. 3. The method according to claim 1 or 2, characterized in that the oC -acids contained in the primary extract by boiling the aqueous solution of an extract containing a sufficient amount of sodium and / or potassium carbonate to achieve a pH of about 8 to 11 during a period of Isomerized for 5 minutes to 2 hours. 4. The method according to claim 3, characterized in that the aqueous solution to a temperature of cools no more than 40 C and acid is added to the solution up to a pH value of 2 to 5 for precipitation the ß-acids from the solution with subsequent filtration or centrifugation of the solution for removal of the precipitated ß-acids. 8098 16/0769 5. The method according to claim 4, characterized in that that the filtered aqueous solution by evaporation, preferably under vacuum, to a predetermined level concentrated at a temperature not exceeding 50 ° C and before, during or after the concentration adjusts the solution to a pH of about 8 to. 6. The method according to claim 4, characterized in that the concentration of iso ^ acids in the Adjust solution to no more than about 5 g / l prior to acidification. 7. Use of the iso- · * acids prepared according to claims 1 to 6 for bittering beer. Π09 0 1Π / 0789