DE1923072A1 - Process for extracting hops - Google Patents

Description

Dr. F. Zumsfein - Dr. E. Assmann '923072 Dr. R. Koenigsberger Dipl. Phys. R, timber builder Patent attorney Munich 2, Bräuhaussfrafre 4/111

Case 25.9O-751

ALLIED BREWERIES LIMITED London EC1 , United Kingdom

Process for extracting hops.

The invention relates to the extraction and use of the bitter substances of 'hops.

When brewing beer, the usual way of working is to use of hops as a bitter substance is a comparatively ineffective process (10 to 4-0%), as a large part of the potential Bitter substances, the α-acids, are lost during the brewing process. The alpha acids include humulone, cohumulone and adhumulone and are sometimes referred to collectively as humulones. Their isomerized forms, which are those obtained from hops The main request he substances are hereinafter referred to as iso-oc acids denotes and includes iso-humulon, iso-cohumulon and iso-adhumulon, which is sometimes collectively referred to as "iso-humulory" will.

In the normal brewing process, the hops are boiled in the wort in order to convert the α-acids into the iso-α-acids, which give the finished beer its characteristic bitter hop taste. It was found that on average only 40 %

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of the bitter substance potential of the hops survive this wort boiling process, while a further variable loss occurs during the subsequent fermentation, which leads to a total use of about 20 % of the original α-acids or absorption of the α-acids and iso-α-acids on the protein-polyphenol precipitate or cloudiness (break) formed during boiling. The removal of this precipitate by filtration leads to a significant loss of the brewing value of the hops as a bitter substance

It is therefore desirable to extract the bitter substances from the hops and the extract during the brewing process after removal of the turbidity (break) and preferably after fermentation to add the wort. ■

The hops usually added during the boiling of the wort have certain beneficial effects that are not related to the Flavor related, and it is desirable that There should be some hops at this stage. Nevertheless however, an increase in the effectiveness of the hop utilization can be achieved by removing a large proportion of the hops replaced by an extract that is added after the wort has been boiled or fermented

A number of different hop extracts have been suggested for use in brewing, but these have not had the effect of reducing the effectiveness with which hops are used, although extracts have the general advantage of being easier to store than hops themselves prior to use. In most of the proposed extraction processes, the hops are extracted with organic solvents such as e.g. B. chlorinated hydrocarbons, extracted to extract the flavor and bitterness, and the resulting α-acid material is then usually isomerized to convert the α-acids present to iso-α-acids. So far, these processes have provided an iso-a ~ acid material that contains significant amounts of substances associated with it, such as ß-acids, humulinic acid and resins as well as ^:

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Lipoids that go rancid and have an undesirable aftertaste lead, was contaminated.

It has now been found that the high purity of the extract is important for the effective use of hops for bittering of beer. It has been found that in wort or beer, a reaction between the iso-oc acid and others is normal existing impurities takes place, which removes a considerable part of the iso-α-acids from the wort or the beer. It has now been found that when practically pure iso-α-acids are added to the beer, practically all of the iso-α-acid material is effective as a bitter substance and can then be recovered, while when the same material is added to the beer in The presence of impurities usually associated with the iso-oc acids in isomerized hop extracts is the bitter-making Effect is greatly reduced and the iso-ot-acids are not can be fully obtained. However, if a citrate buffer is used instead of the beer at the same pH value, the Iso-ot-acids in both the presence and absence of the above described impurities are recovered. A triple transposition that was previously unknown appears to be occurring between the wort or the beer, the iso-oc acids and some or all of the other hops components used in common isomerized hop extracts are present. The loss of the "bitter-making effect" apparently occurs immediately with the addition of the usual Hop extracts are added to the wort or beer and can only be added by adding an excess of isomerized extract which allows the bitter substance to be removed, which means that additional hops have to be used.

From these studies it appears that it is of greater importance is than previously assumed that from an iso-oc acid preparation the impurities are removed for adding to cooked wort or beer.

It has now been found that for the production of a high-purity iso-acid, which is necessary to avoid the loss of bitter substance due to the reactions described above, especially it

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_ Zj. _

(gland)

is advantageous, lupulin, the umbel material / in the hop flower, which contains the greater part of the bitter and taste substances to extract; it was also found that lupulin containing materials, such as. B. hops themselves or hop powder, also extracted and isomerized with aqueous alkali can be, wherein the extract obtained is then subjected to a further purification to an iso-a-acid extract with improved Achieve purity.

The present invention therefore relates to a process for the preparation of an iso-α-acid extract from a lupulin-containing material, such as. B. lupulin itself, hops or hop powder, which is characterized in that this material is treated with an aqueous alkaline solution to produce an aqueous extract containing the iso-ot acids, that this extract is then subjected to a further purification to at least partially produce the impurities therefrom to remove _# and an iso-a-acid-extract, which has an improved bitter-making effect.

In a modification of the process according to the invention, lupulin an extraction and isomerization treatment with aqueous alkali, preferably at pH 9 »and the obtained Extract is preferably treated for 30 to 4-5 minutes in order to remove the solids to form an aqueous extract containing the iso-α acids. So can, starting from lupulin itself, by alkaline extraction and isomerization, an aqueous extract can be produced in which the iso-oc acids are in relatively pure form. In this process, the iso-α-acids can be obtained by extracting the separated solid can be obtained with water, for example when boiling.

It has now been found that for maximum yields of iso-oc acid from the lupulin or the lupulin-containing material the pH value the alkali solution used in the extraction and isomerization is decisive. At low pH the isomerization is very low even at 100 C and long periods of heating are required. At high pH values, however, both

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the extraction of undesirable products, such as. B. the ß-acids and the oxidation products of ß-acids, as well as the formation the unwanted by-products, such as. B. humulinic acid promoted .

The preferred pH values are therefore in the range of 8.5 to 9j5 and it is therefore advantageous to use sodium carbonate as an alkali to use. The extraction and isomerization temperature is preferably the reflux temperature of the solution, but can lower temperatures are also used for longer periods of time will. The pH value, the reaction temperature and the reaction time depend on each other and the optimal conditions for any given material can most easily be determined experimentally, the yield and the chosen Conditions at which the greatest yield is achieved can be monitored, for example, by thin layer chromatography can.

When using a previously set to pH 9 »0 and 95 G pH meter can achieve a maximum yield of iso-oc acid after 30 to 45 minutes of boiling can be achieved. When measuring the pH with a universal indicator it is slightly above room temperature find a discrepancy and the pH is actually lower. A pH measuring device set to pH 9.0 and 95 ° C. gives the result at room temperature a pH value of 9 »7 ·

The amount of iso-oc acids available in the solution after isomerization is inversely proportional to the lupulin concentration (g / l). For example, it has been found that a concentration of 100 grams of lupulin per liter gives a recovery of 25% iso-oc acid, while a concentration of 10 grams per liter gives a recovery of 65%. It has been found that for practical purposes a concentration of 10 g per liter is advantageous.

It has been found that macerating the lupulin, for example using a Silverson mixer or an ultrasonic vibrator for breaking the lupulin pockets / immediately before isomerization is advantageous, with the yield on

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Iso-a-acids is improved from 65 to about 72%.

After the isomerization has ended, the solution containing the iso-cx acid can be concentrated and further purified. This can be achieved by acidification to pH 1 and subsequent isolation of the iso-a-acid. If hops are used as the raw material, the solution should preferably be filtered before acidification. Acidification may be for any conventional mineral acid, for example sulfuric, phosphoric or hydrochloric acid is used _o Upon acidification the iso-.alpha.-acid in the form of a fine gelatinous precipitate axis which does not settle falls. This precipitate is expediently purified by adding an inert absorbent, such as. B. diatomaceous earth to settle, discard the above-mentioned liquid and wash the solid with an aqueous solution, for example a hot sodium or calcium carbonate solution at pH 8 to 9.

Alternatively, the acidified mixture can be extracted with a water-immiscible organic solvent, the organic solvent then with a weak, basic aqueous solution, for example a buffer solution, is back-extracted. When using a second extraction with With aqueous alkali, surprisingly effective further purification is achieved using inexpensive materials. The received basic solution contains highly pure iso-a-acid, if desired can be used as such as an additive to wort or beer. Alternatively, the aqueous basic extract acidified and extracted with an organic solvent, which can then be evaporated, or the basic one Extract can be an evaporation, spray drying, accelerated Freeze-drying process or a similar process be subjected to remove the water.

The pH of the weakly basic solution used for the second alkaline extraction is important for obtaining a pure iso-oc acid extract. It has been found that pH values in the range of 8 to 9 are required for optimal cleaning. pH- . Values above 9 lead to an increased extraction of ß-acid

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ren and ß-acid oxidation products from the organic phase, whereby the degree of purity achieved is deteriorated. pH values below 8 reduce the yield of from the organic phase obtained iso-oc acids. To suitable weakly basic solutions include sodium or potassium carbonate or carbonate solutions or phosphate or citrate buffer * The buffer volume used depends of course on its strength, but expediently the volumes of buffer and iso-α-acid solution are in the same order of magnitude.

Suitable solvents for the extraction are, for example, chlorinated hydrocarbons, such as. B. methylene chloride, water-immiscible ethers such. B. diethyl ether, or hydrocarbons, such as. B. benzene or petroleum ether. The solvent of choice is petroleum ether. The optimum volume of the extraction solvent will vary with the nature of the solvent and other factors, however, the ratio of aqueous phase to organic phase in the extraction is preferably in the range of 1 to 1 to 1 to 3.

It is advantageous to add the solvent before acidifying the solvent, since the iso-α-acid has a tendency to precipitate and, once precipitated, this material is more difficult to dissolve and extract. By adding the solvent first, it is ensured that the iso-a-acid remains in solution during the extraction stage «

Alternatively, the 'solvent can be added after acidification but this addition is preferably not delayed in order to minimize precipitation. However, it is possible that the Iso-a-acid. To precipitate and the precipitated sludge to separate this sludge by centrifugation or filtration and subsequent extraction with a solvent. The on However, the yields obtained in this way are not as good as those obtained in the liquid-liquid extraction.

As a source of that used in the isomerization process α-acid can be a lupulin-containing material such. B. hops

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or hop macerates, etc. can be used. However, preference is given to using pure lupulin, as this, although only 16 to Makes up 20% by weight of the hops, essentially all of the flavor substances and contains up to 30% by weight of the α-acid. Using modern methods, the lupulin can be extracted from the hops by froth flotation etc. are separated in very high yields. In addition, the lupulin is separated out at an early stage of the hop harvest the lupulin losses due to contact, etc. are greatly reduced and a higher yield of α-acid is obtained per acre. When using lupulin itself, the process according to the invention gives higher yields than when using it of hops and although in the separation of the lupulin from the Hops, some material can be lost, this is more than offset by the higher yields in the later stages. The following examples are intended to illustrate the invention without, however, restricting it thereto.

example 1

30 g of lupulin (30% α-acid) were dispersed in 700 ml of distilled water and, after adjustment to pH 9 (universal indicator), boiled under reflux for 2 to 2 1/2 hours by adding aqueous alkali, during which time the isomerization of the α-acid was practically completed. Subject of the isomerization, the aqueous solution was acidified to pH 1 by adding hydrochloric acid and extracted with petroleum ether. The resulting solution was then extracted with aqueous sodium bicarbonate (1.10 wt. ^ 6, pH 8 to 9) and gave a practically pure solution of the iso-α-acid. Acidification of this iso-α-acid rich aqueous solution, subsequent back-extraction with petroleum ether and subsequent evaporation of the solvent gave 8.9 g of a resin which contained 81 % iso-α-acid. This corresponds to a total recovery of 80% of the original α-acid material in the iso-α-acid form.

Example 2

a) 30 g hops (6.58 % α-acid) were distilled in 1500 ml

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Water dispersed and after adjustment to pH 9 (universal indicator) boiled by adding aqueous alkali under reflux for 2 to 2 1/2 hours, during which time the Isomerization of the ά-acid was practically complete. After isomerization, the aqueous solution before extraction with 200 ml petroleum ether by adding hydrochloric acid acidified to pH 1

b) Alternatively, after isomerization, the aqueous solution was filtered to remove the hops with hydrochloric acid acidified to pH 1 and extracted with petroleum ether. The filtered hops became after dispersion in distilled water also acidified to pH 1 and extracted with petroleum ether to remove any iso-oc acid still adsorbed on it.

c) The petroleum ether solution originating from one of the above-mentioned processes a) and b) was mixed with aqueous sodium bicarbonate (5 % By weight, pH 8 to 9) and yielded a practically pure solution of the iso-α acids. After acidifying this with iso-oc acid rich aqueous solution and the subsequent back extraction obtained with petroleum ether and evaporation of the solvent 1.65 g of a resin which contained 80% iso-α-acids. This corresponds to a total recovery of 66.5% of the original oc-acid material in the iso-oc-acid form.

Example 5

15 g of lupulin (14.8 % alpha acid) was weighed into a round bottom flask and macerated in 15ΟΟ ml of distilled water for 15 minutes using a Silverson mixer. The mixture obtained was adjusted to pH 9 * 0 by adding a sodium carbonate solution (10% by weight / volume) and boiled for 30 minutes, after which the isomerization of the α-acids was practically complete.

The isomerization mixture was cooled to 20 ° C. and allowed to settle, the liquid above was decanted off. Of the Leached lupulin sludge was washed with distilled water (approx 1 1) Boiled for another 15 minutes, allowed to settle and the

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part above decanted again. Analysis of the United The above parts showed a 96% recovery of the available α-acids in the form of iso-α-acids.

The addition of the isomerized solution to beers gave no off-taste and showed 60% use of the iso-alpha acids.

Example 4

To the above liquids obtained in Example 3, 2 w / v. % of a filter mass (kieselguhr) was added and the mixture was stirred well during the rapid addition of 30 ml of concentrated hydrochloric acid. The resulting precipitate was allowed to settle with the filter mass and the clear liquid above was decanted off and discarded. The precipitate was washed with a boiling aqueous sodium carbonate solution at pH 9 »0 and yielded a purified and concentrated solution of the iso-α-acids. Analysis of this solution indicated that 72% conversion of the original alpha acids had been obtained. The addition of this extract to beer gave no off-taste and resulted in 66% use of the iso-α-acids.

Example 5

30 g of lupulin (23.8 % α-acid) were dispersed in 600 ml of distilled water and, after adjusting to pH 9 by adding aqueous alkali, refluxed for 2 to 2 1/2 hours, during which time the isomerization of the α-acid was practically completed. After the isomerization, the aqueous solution was cooled to 20 ° C. and quickly acidified to pH 1 by adding 5 ml of concentrated hydrochloric acid in order to precipitate the acid-insoluble hops at the edge. The solids (leached lupulin and precipitated material) were removed by centrifugation and the above liquid, which contained a negligible amount of isoliumulone, was discarded. Extraction & the solids with an aqueous sodium or potassium bicarbonate solution (1 to 10%) at 80 ° G

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yielded a solution which, in the analysis, contained 4.95 g of iso-oc acid. This corresponds to a total recovery of 69j 5% of the original α-acids.

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Claims (1)

Claims 1. Process for the preparation of an iso-a-acid extract from
a material containing lupulin, such as e.g. B. lupulin itself, hops or hop powders, characterized in that the material is treated with an aqueous alkaline solution to produce an aqueous extract containing the iso-oc acids that this extract is then subjected to at least partial further purification in order to To remove impurities from it and to deliver an iso-ot-acid extract that has an improved bittering effect. 2. The method according to claim 1, characterized in that the The pH of the aqueous alkaline solution is 8.5 to 9 »5. 3. The method according to claim 2, characterized in that the pH is 9.0. 4-. Method according to one of the preceding claims, characterized in that that the aqueous alkaline solution used contains sodium carbonate. 5. The method according to claim 3 _f, characterized in that the isomerization is effected by boiling the solution for 30 to 45 minutes. 6. The method according to any one of the preceding claims, characterized in that an amount of about 10 g of lupulin per liter aqueous solution is used. 7. The method according to any one of the preceding claims, characterized in that the material macerates before isomerization will. 8. The method according to any one of the preceding claims, characterized in that the extract is then acidified to pH 1 will. 909847/0656 '9 · Method according to claim 8, characterized in that the iso-ot-acids detected with an inert absorbent or by Centrifugation can be brought to settle and the solid is extracted with an aqueous solution at pH 8 to 9. 10. The method according to claim 9 »characterized in that kieselguhr is used as the inert absorbent. 11. The method according to claim 9 or 10, characterized in that a sodium or potassium carbonate solution as the aqueous solution is used. 12. The method according to claim 8, characterized in that the iso-oc acids from the acidified extract in an organic, are extracted with water immiscible solvent that the solvent then with a weakly basic aqueous Solution is back extracted. 13 · The method according to claim 12, characterized in that the aqueous solution used has a pH in the range from 8 to 9 ". · I 14. The method according to claim 12, characterized in that a sodium or potassium carbonate or bicarbonate solution is used as the solution or a phosphate or citrate buffer is used. 15 «Method according to one of claims 12 to 14, characterized in that that the organic solvent is a chlorinated hydrocarbon, a water-immiscible ether or a Hydrocarbon is used. 16. The method according to claim 15 »characterized in that the solvent is methylene chloride, diethyl ether, benzene or petroleum ether is used. 17. The method according to any one of claims 12 to 16, characterized in that that the ratio of aqueous phase to organic phase is in the range from 1: 1 to 1: 3. . 909847 / 06S6 18. The method according to any one of claims 12 to 17 j, characterized in that that the solvent is added before acidification. 19 · Modification of the method according to one of claims 1 to ~~ 7 "» thereby characterized in that lupulin itself is used as the material and the aqueous extract is treated to make the solid Separate material from it. 20. The method according to claim 19 »characterized in that the separated solid material is extracted with water in order to obtain further iso-oc acid therefrom. 21. The iso-oc- obtained by the method according to claim 1 ■ Acid extract. ORIGINAL INSPECTED 9098A7 / 06SS