PL212630B1 - Method for refining hop extracts for beer production - Google Patents

Description

The subject of the invention is a method of refining hop extracts for the production of beer, without diluting them with water and without the presence of liquid or supercritical carbon dioxide. The term refinement is understood to mean the isomerization of alpha acids to isoalpha acids and the simultaneous introduction into the extract of magnesium or potassium or calcium or a mixture thereof.

Hops extracts, being a mixture of mainly alpha acids, beta acids, essential oils, hard resins, waxes and water, obtained mainly by extraction with carbon dioxide under supercritical conditions, i.e. at a pressure above 7.5 MPa and at a temperature above 31 ° C, are added in most breweries, the wort is brewed in order to give the beer the desired bitterness and aroma. In this process, 45 - 65% of the alpha acids are isomerized to isoalpha acids, which give the beer its characteristic bitterness. The remaining alpha acids, being insoluble in water, are separated from the beer in the filtration process and are irretrievably lost. The optimal concentration of isoalpha acids in beer, ensuring its best taste, is 25 - 35 mg / l. In order to increase the use of alpha acids contained in hops and extracts to 80 - 95%, and thus reduce their losses, their initial isomerization is applied, i.e. before adding to the wort. Beta acids contained in the extracts have a positive effect on the fermentation process of the wort and the oils give the beer a pleasant aroma, also called aroma.

Various methods of alpha isomerization of the acids contained in hops and in hop extracts are known. They can be divided into three main groups: isomerization in aqueous solutions, isomerization "dry" and isomerization in liquid or supercritical carbon dioxide. The best known and most frequently used on an industrial scale is isomerization in an aqueous medium at a temperature of about 100 ° C. The extract is first mixed with degassed water and heated to about 90 ° C under a nitrogen atmosphere. A so-called "catalyst", in the form of a magnesium or potassium oxide or carbonate, is then added to this solution and heated to about 100 ° C. Soft gums and waxes are separated from the solution, then the pH is lowered from 7-8 to 5-6 and the beta layer of acids is separated. The remaining alpha acid layer is acidified to pH 2 and diluted with water to 20 or 30% isoalpha acids. The ready solution of pure isoalpha acids is packed into standard packages. These types of solutions are mainly used to correct, i.e. increase the bitterness of beer.

The disadvantage of this method is its complexity and implementation costs, separation of beta acids, high losses and separation of oils.

Another known method of isomerizing extracts is by heating them below the boiling point and mixing them in an aqueous solution of NaOH and MgSO4. The aqueous layer is then separated and the organic layer is a so-called isomerized kettle extract which, after being made alkaline with KOH, is known as PIKE. The disadvantages of this method are: its complexity and high loss of oils.

There is also known a method according to Polish patent No. 58 304 consisting in dissolving the extract in petroleum ether and adding an aqueous solution of sodium or potassium carbonate with a concentration below 5 g / 100 ml of the solution until the pH is 9 - 9.8. The aqueous phase is then separated from the organic phase, which is boiled with an aqueous alkali solution.

Another common method for "dry" alpha isomerization of alpha acids, according to US patents 4123561 and 4154865, is to add a "catalyst" in the form of CaO or MgO, or a mixture thereof at 0.5-3%, to the hop mill prior to pelleting. The hop pellets are kept at ambient or elevated temperature up to 40-100 ° C, preferably up to about 50 ° C, for a period of about 2 weeks. The disadvantages of this method are: high losses of oils, high energy consumption and intended only for breweries using hop pellets, the number of which is systematically decreasing.

According to US patent 5,015,491, the hops extract can be "dry" isomerized by mixing it with a solid compound (bicarbonate, carbonate, oxide, hydroxide) of an alkali metal Na, K, Mg, Ca in a molar ratio of 0.1 - 4, preferably 1 - 3 , and heating to a temperature of minimum 80 ° C, preferably 120-140 ° C. The disadvantages of this method are: a solid product, almost without oils, high energy consumption, specialized expensive equipment, danger of burning the mixture and thermal decomposition of some compounds contained in the extract.

A "dry" isomerization process in supercritical CO 2 is known according to US Patent No. 4,338,348. Adsorptive agents, for example silicone gel, diatomaceous earth, bentonite, alkali metal salts and oxides, are added to the extract. The addition of adsorbent is from 0.01 to 10 in relation to the weight of alpha acids. Isomerization in supercritical CO2 is effective as low as 5 MPa, preferably 20-30 MPa. Good results are also obtained with pressures above

PL 212 630 B1

MPa, but then the process is very energy-consuming and requires more expensive equipment. The minimum process temperature is above 33 ° C, but isomerization is faster at temperatures above 80 ° C. The isomerization time depends on the parameters of CO2 and the form of the hops product and ranges from a few minutes to several hours. The main disadvantages of this method are: high-pressure, complicated and expensive apparatus and energy consumption.

Yet another method of isomerization, described in the French patent FR 2,590,589, consists in irradiating the extract dissolved in liquid or supercritical carbon dioxide at a pressure of 5-30 MPa, at a temperature of 0 - 75 ° C, with UVA rays with a wavelength of 250 - 450 nm. The source of radiation can be a laser or special lamps and filters. The disadvantages of this process are the same as that described above.

The process of the invention overcomes or reduces the disadvantages of the known methods described above. It is most similar to that described in US patent 5,015,491. The main differences are as follows:

- a small amount of aqueous ethyl alcohol is added to the hop extract to lower its viscosity and facilitate mixing with a solid isomerizer, also known as a "catalyst",

- the isomerization of extracts is carried out at low temperature, i.e. below 60 ° C,

- the time of the isomerization process is many times longer and this process can also take place in containers with the finished product,

- the content of elements valuable for the human body, such as Mg or K or Ca in the extract, can be significantly increased in order to make the beer additionally a dietary supplement,

- the isomerized extract can be in a liquid form rather than a solid by adding an appropriate amount of a diluent, i.e. an ethyl alcohol solution.

The essence of the invention is that an aqueous solution of ethyl alcohol with a concentration of 40 - 96% by volume, in the amount of 0.1 - 1 in relation to the volume of the extract, is added to the extract and mixed, and then an isomerizer is added, which is an oxide or hydroxide of magnesium or potassium. or calcium or any mixture thereof, in the form of a solid, fine-grained, i.e. powder or small granules with a grain size of less than 2 mm, in the amount of 1.1 - 50 moles per mole of alpha acids, and the resulting homogeneous reaction mixture is kept in ambient temperature or less than 60 ° C, preferably under an inert atmosphere to prevent oxidation of the alpha acids. For example, carbon dioxide or nitrogen or a mixture thereof may be present above the reaction mixture. The isomerization process is carried out in homogenizers equipped with a stirrer, preferably immediately after supercritical extraction with carbon dioxide and / or in the packaging process and / or in product packaging, which should be made of a material that does not transmit light, due to the sensitivity of isoalpha acids to UV radiation . The isomerization process in product packages can be accelerated by storing them for several hours to two weeks at a temperature above the ambient temperature and below 60 ° C.

Unexpectedly, it turned out that the process of alpha acid isomerization also takes place at a satisfactory rate at low temperature, in the absence of liquid or supercritical carbon dioxide, in an aqueous solution of ethyl alcohol, in contact with a powdered isomerizer, being a magnesium or potassium or calcium oxide or hydroxide. or any mixture thereof. Proper selection of the concentration and amount of ethyl alcohol solution in relation to the mass of the isomerizer does not result in the formation of two liquid phases after the isomerization. It is generally known that MgO and CaO, upon contact with water, rapidly react to Mg (OH) 2 and Ca (OH) 2 and therefore it does not matter whether the isomerizer is an oxide or a hydroxide.

For standardization, that is, to correct the content of isoalpha acids in the product to the desired value, a known additive such as glucose or a saturated solution of sucrose or other sugar can be used. Due to the sensitivity of isoalpha acids to UV radiation, containers with the product should be made of light-proof material.

The implementation of the invention is illustrated in the examples below. The examples used hops extract containing: 40.5% alpha acids, 20.9% beta acids and 4.6% oils. ₃ density of the extract was about 1 g / cm ^3. 1 g of the extract was assumed to contain approximately 1.1 mmol of alpha acids. The concentration of ethyl alcohol in aqueous solutions is given in% by volume. The analyzes of the extracts were performed using the high performance liquid chromatography method, abbreviated to HPLC, for High Performance Liquid Chromatography.

P r z k ł a d 1

To 50.4 g of hop extract, 10 ml of 96% aqueous ethyl alcohol solution was added and mixed. Then 4.5 g of MgO in the form of a powder with grains smaller than 0.2 mm was added and mixed. The reaction mixture was covered and left at ambient temperature for 4 days. At this time, HPLC analysis showed 29.8% isoalpha acids and 2.5% alpha acids. The degree of alpha isomerization of acids

The PL 212 630 B1 was thus about 92%. Another analysis was performed after another 10 days, i.e. 14 days after the mixture was prepared. There was an increase in the degree of isomerization by 3.6%, ie up to 95.6%.

P r z k ł a d 2

To 50.7 g of hop extract, 50 ml of 50% aqueous ethyl alcohol solution was added and mixed. Then 32 g of CaO in the form of a powder with grains smaller than 1 mm was added and mixed. The reaction mixture was covered and left at ambient temperature also for 4 days. At this time, HPLC analysis showed 15% isoalpha acids and 1% alpha acids. The degree of isomerization was almost 94%. The re-analysis was performed analogously to example 1. There was an increase in the degree of isomerization by 3.8%, that is to 97.8%.

P r z k ł a d 3

To 50.2 g of hops extract, 25 ml of 75% aqueous ethyl alcohol solution was added, mixed and placed in a water bath at a temperature of about 50 ° C. Then 16 g of powdered KOH with grains smaller than 0.4 mm was added and mixed. The reaction mixture was covered and left for 3 hours. At this time, HPLC analysis showed 22.4% isoalpha acids and 0.8% alpha acids. The degree of isomerization was thus approximately 96.5%.

P r z k ł a d 4

To 51.0 g of the extract was added 25 ml of a 75% aqueous ethyl alcohol solution and mixed. Then 2.3 g of MgO powder with grains smaller than 0.2 mm and 3.2 g of KOH powder with grains smaller than 0.4 mm were added and mixed. The reaction mixture was closed and left at ambient temperature for 4 weeks. At this time, HPLC analysis showed 26.0% isoalpha acids and 0.5% alpha acids. The degree of isomerization was approximately 98.1%.

P r z k ł a d 5

To approximately 6 kg of the extract at 42 ° C in the homogenizer, 3 liters of 96% ethyl alcohol were added and mixed. Then 360 g of MgO in the form of a powder with grains smaller than 0.2 mm was added and mixed. The homogenizer was purged with carbon dioxide, capped and left for 4 hours. After this period, the reaction mixture was heated to 45 ° C, mixed, a sample was taken for analysis, and then it was filled into metal cans with a capacity of 0.5 L. Before filling the cans, the reaction mixture contained 15.5% isoalpha acids and 12, 2% alpha acids. The degree of isomerization was thus approximately 56%. The sealed cans of the reaction mixture were stored at ambient temperature. After 8 weeks, a sample was taken from one of the cans for analysis. It was found that the content of isoalpha acids increased to 27.1% and the content of alpha acids decreased to 0.6%. The degree of isomerization therefore increased to about 97.8% during this time.

Claims (5)

A method of refining hop extracts for the production of beer, consisting in their isomerization and enrichment in Mg, and / or K and / or Ca, using an isomerizer which is an oxide or hydroxide of these metals or any mixture thereof, characterized in that the extract is added to an aqueous solution of ethyl alcohol with a concentration of 40 - 96% by volume, in the amount of 0.1 - 1.0 in relation to the volume of the extract, and mixed, then an isomerizer, which is an oxide or hydroxide of magnesium or potassium or calcium, or any mixture thereof, is added, solid, fine-grained, i.e. powder or small granules with a particle size of less than 2 mm, in an amount of 1.1 to 50 moles per 1 mole of alpha acids and further mixed and the resulting homogeneous reaction mixture is kept at ambient temperature or below 60 ° C preferably under an inert gas atmosphere. 2. The method according to p. The process of claim 1, wherein carbon dioxide or nitrogen or a mixture thereof is above the reaction mixture. 3. The method according to p. The process of claim 1, characterized in that the alpha isomerization of the acids takes place in agitator-equipped homogenizers, preferably directly after supercritical carbon dioxide extraction and / or in the confectioning process and / or in product packaging. 4. The method according to p. The product of claim 1, wherein the product containers are made of a non-transmissive material. 5. The method according to p. The method of claim 4, wherein the isomerization process in the product packages is accelerated by storing them for several hours to two weeks at a temperature above ambient temperature and below 60 ° C.