GB2147309A - Liquid lupulin concentrate and mechanical separation method - Google Patents

Abstract

Lupulin powder is heated to 65 DEG C and placed into a preheated (65 DEG C) press (10, 14, 16). Pressure applied by a piston (16) is used to express from the lupulin resins which have been liquified by the heat, and essential oils, leaving a press cake comprising cell material and other solids. The liquid concentrate is expressed through a fine mesh screen wall (28) or a fabric bag wall overlaying a coarse screen. Low grade lupulin powder containing considerable fibrous material can be used. A potent viscous liquid concentrate is obtained. <IMAGE>

Description

SPECIFICATION Liquid lupulin concentrate and mechanical separation method The present invention relates to the provision of a method of mechanically separating a liquid concentrate of hop flavor resins and oils from hop lupulin powder, for use in the brewing of malt beverages, and to the product of such method.

As is well known, extracts from hops are used in the manufacture of beer and ale for imparting the characteristic aroma and taste to the beverage. The substances to which the characteristic aroma and taste are attributable are resins and essential oils contained in the lupulin glands (hereinafter simply referred to as "lupulin").

The brewing potency of hop substances used in the manufacture of beer and ale is measured analytically in terms of the percentage of contained organic acids, termed "alpha acids", which are available in the hop substance which is introduced into the wort.

Presently, the highest potency extract of hops used in the commercial manufacture of malt beverages is a viscous syrupy extract of lupulin obtained by solvent extraction. The extract or concentrate obtained by solvent extraction contains as much as 55% alpha acids, depending upon the quality of the hops used and the nature of the extracting solvent.

Solvent extracts are also the most stable form of hop product because they are stored in sealed metal cans and this protects the flavoring constituents from oxidation.

Most solvent extracts contain a small amount of residual solvent which is objectionable to some brewers. Examples of these solvents are hexane and methylene chloride. Carbon dioxide can be used as a solvent without leaving a residue. However, extraction processes using carbon dioxide require a very high pressure to create and maintain the carbon dioxide in a liquid or fluid gas state. For example, extraction by use of super critical carbon dioxide requires the use of extraction vessels which are capable of withstanding pressures of two thousand to six thousand pounds per square inch (psig). Pumps and other accessories capable of operating under these extreme pressures are also required. As a result, the use of carbon dioxide as the extracting solvent requires a very high capital investment for a processing plant of even moderate capacity.

Lupulin is separated from hop cones in many different ways, resulting in different grades of lupulin powder. A high grade lupulin powder is essentially pure lupulin glands. Lower grades include fibrous vegetable matter from the broken bracts of the hop cone. The following United States Patents disclose various methods of separating lupulin from hops: No. 2,833,652, granted May 6, 1958, to Winifred A. Naatz; No. 3,271,162, granted September 6, 1966, to Laurence R. Bishop; No. 3,390,000, granted June 25, 1968 to Robert J. Brison et al; No. 4,051,771, granted October 4, 1977, to Junjiro Miyata et al and No. 4,053,653, granted October 11, 1977, to Junjiro Miyata et al. The alpha acid content of the lupulin powder obtained by these processes ranges from 15% to 37%.The process of the present invention can be applied to various grades of lupulin powder, such as between 20% and 50% alpha acid.

British Patent No. 1,190,670, published May 6, 1970, proposes a process of crushing or grinding lupulin powder to form a paste consisting of the resins and essential oils, which are freed by the mechanical crushing, and the cellular material of the lupulin. Experiments with this process established that it can only be successfully used with high grade lupulin powder. The presence of even small amounts of fibrous matter made the resulting mixture too dry. When substantially pure high alpha acid content lupulin was used, a semi-fluid paste was produced which became a free-flowing liquid when heated. However, when a lower grade of lupulin was used, having a lower alpha acid content, due to the presence of finely divided fibrous vegetable material from the broken bracts of the hop cone, the resulting product was dry and non fluid and could not be made a fluid by heating.

The present invention seeks to provide a method of mechanically separating flavor-producing resins and essential oils from hop lupulin which can be used successfully to process both high and low grade lupulin powders to obtain a substantially pure concentrate. Mechanical pressure is used to crush the walls of the lupulin glands, to free the resins and essential oils. However, instead of the freed resins and essential oils and the lupulin wall material being ground together, the process of the present invention separates the liquids from the solids. The fluidizable resins and essential oils are mechanically expressed from the hop lupulin solids as they are freed from the cells, leaving all solids behind in the form of a press cake.Whatever fibrous vegetable matter might exist in the lupulin powder is left behind in the press cake, together with the cellular wall material of the lupulin glands.

The method of the present invention comprises heating a quantity of hop lupulin powder to melt resins contained therein; applying pressure to the heated hop lupulin powder to rupture the lupulin and to express therefrom a viscous liquid concentrate of hop flavor resins and essential oils, substantially free of cellular material, and at the same time produce a residue press cake comprising cellular material; and separating the viscous liquid concentrate from the press cake material.

In accordance with an embodiment of the invention, the viscous concentrate is expressed through a wall of material which is permeable to the concentrate but not to the solids which make up the press cake. The wall may be a screen wall with mesh openings smaller in size than intact lupulin glands, or a fabric wall with similar size openings.

If a screen wall is used, the lupulin powder is placed directly on the screen wall and pressed. If a fabric wall is used, the lupulin powder is placed in side of a bag constructed from the fabric and the bag is pressed.

An important matter is the recognition that the press cake can be further processed by the use of solvents to in that manner extract whatever available alpha acids which remain in the press cake.

The two products produced by the two processes are not mixed together. Rather, the solvent-residue-free product of the mechanical separation process is sold into those markets requiring a solvent-residue-free product. The product produced by treating the press cake with a solvent is sold into a market which will accept a slight amount of solvent residue in the product.

In another aspect there is provided apparatus for expressing flavor resins and oils from hop lupulin which has been preheated to melt resins contained therein, comprising: a cylinder having an open end and an end closure end member at the opposite end, the end closure member having an inner surface formed to include a pattern of channels leading toward a collection opening; a screen member overlaying the channels; the cylinder including a discharge opening in communication with the channels; and a piston insertable into the cylinder; whereby in use the piston and cylinder are preheated and preheated hop lupulin is placed between the screen and the piston and the piston is moved toward the screen to express a viscous liquid concentrate of hop flavor resins and oils from the lupulin which is substantially free of cellular material, and at the same time producing a residue press cake comprising cellular material.

Also included within the invention is a method of brewing which comprises the method of the invention, the use of the inventive apparatus or the use of hop lupulin concentrate prepared using the method or aparatus of the invention. Further included are beverages brewed by such methods.

The present invention is further described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a flow diagram of both the primary method of the present invention and an optional secondary phase method; Figure 2 is an exploded pictorial view of a press of a type that was actually used to practice the invention; Figure 3 is an enlarged scale vertical sectional view taken through the press, showing a quantity or charge of lupulin powder positioned between a piston and a small mesh screen; Figure 4 is a view like Figure 3, but showing the lupulin powder within a bag and the bag positioned between the piston and large mesh support screen for the bag; and Figure 5 is an enlarged scale pictorial view showing channel forming grooves in the upper surface of a closure member for the lower end of the press cylinder, and further showing a discharge opening into which the grooves drain.

In the drawing, like reference characters refer to like parts throughout.

Referring to Figure 1, lupulin powder is separated from hop cones in any known manner, such as by threshing. Next, the lupulin powder is heated to a temperature sufficient to melt the resins within the lupulin glands. The heated lupulin powder is then placed into a press, the parts of which have been heated so that they will not cool down the resins. Alternatively, the lupulin in the press is heated together with this press by some means such as a heating jacket. Within the press, the heated lupulin powder is force fed against a permeable wall of material having openings therein which are smaller in size than intact lupulin glands. A sufficient amount of pressure is applied to both break the walls of the lupulin and express the freed resins and essential oils out through the permeable wall, away from the solids.A concentrate is produced which is in the nature of a viscous syrup or liquid, high in alpha acid content and substantially solid free.

The solids are compressed in the press into a press cake which might contain sufficient additional alpha acid to warrant its further processing by solvent exraction (labeled "optional secondary phase method"). If the press cake is solvent processed, the resulting extract is not mixed with the concentrate obtained by mechanical separation.

Rather, the concentrate produced by mechanical separation is sold into a market requiring a concentrate which is free of an extracting solvent residue. The extract recovered by solvent extraction of the press cake is sold into a market which will accept an extract which includes a small amount of extracting solvent residue.

The essential features of the press are that it be capable of applying sufficient pressure to express the resins and essential oils from the lupulin powder while at the same time retaining the solid structural material of the lupulin glands and any fibrous material which might be present. Various types of commercially suitable presses should be available, as the pressing of fats and oils from other types of vegetable materials, e.g. cocoa beans and other oil-bearing seeds, is a well established technology.

Figures 2-4 illustrate a simple form of press which was used to test and prove the method of the present invention.

Referring to Figure 2, the press is shown to comprise a cylinder 10 defining an inner chamber 12. A lower end closure for the chamber 12 is shown in the form of a plug 14 which is insertable into the lower end of cylinder 10. A piston 16 having a piston head 18 at its lower end is insertable into the chamber 12 through the upper end of the cylinder 10. Member 14 provides a fixed closure for the lower end of chamber 12 and piston head 18 provides a movable closure for the upper end of chamber 12.

Piston head 18 is formed to include a peripheral groove into which a seal ring 24 is placed, to seal against leakage between piston head 18 and the sidewall of cylinder 10.

By way of typical and therefore nonlimative example, the upper surface of end member 14 may be formed to include a pattern of concentric "V" shaped channels or grooves 20. The raised ridges between the channels 20 are wide, relative to the width of the channels 20. The concentric channels 20 are cut by three radial channels 21, one of which has vertical holes 22 drilled along it. These holes 22 are positioned at the points where concentric channels 20 meet this radial channel. The holes which may measure 1/16" (1.6 mm) in diameter, for example, are drilled through to an inner horizontal collecting duct 23 (e.g. about 3116" (4.8 mm) in inner diameter) which is positioned directly beneath the main radial channel and leads to drain opening 26.

There are two peripheral grooves cut into the side of the member 14- one above and one below the collecting duct outlet - for placement of seal rings 24, to seal against leakage between end member 14 and the sidewall of cylinder 10.

A screen 28 is supported on ridges 30 formed between the grooves 20. Screen 28 is attached at its edges to the member 14, such as by welding or by use of an epoxy resin or other suitable adhesive. The sidewall of cylinder 10 is formed to include an outlet opening 32 which is aligned with drain-opening 26 when closure member 14 is inserted into the lower end portion of cylinder 10.

The cylinder 10 and the piston 16 are heated before use. A quantity or charge of lupulin powder is also heated, such as in an oven, and is then poured into the preheated cylinder, onto the screen 28. The screen 28 has an opening size which is smaller than the size of intact lupulin glands, so the lupulin powder will not fall through but rather will be retained on the screen 28. The cross-sectional dimension of an average lupulin gland is about 0.15-0.2mm.

The preheated piston 16 is then inserted into the cylinder 10 and the assembly is placed between the plattens of a hydraulic press. The lower end of the assembly rests on the lower platten and the upper platten makes contact with the upper end of piston 16. Hydraulic cylinders are used for moving the plattens relatively together.

The liquified resins and essential oils begin to flow out through outlet opening 32 when the pressure on the lupulin powder reaches approximately 500 psig (3.42 MPa). The pressure on the lupulin powder is progressively increased up to 5000 psig (34.2 MPa), or more, to obtain a maximum yield of the liquid concentrate. Following the pressing, the piston 16 and the lower end closure member 14 are removed from the cylinder 10, the press cake is removed from the screen 28, and the apparatus is cleaned.

An alternative procedure is to place the heated lupulin powder inside of a tightly woven fabric bag 30, such as a canvas or Nylon bag, and then place the bag 30 into the cylinder chamber 12, onto a coarse screen 28' (Figure 4). The use of the bag 30 facilitates removal of the press cake and preparation of the assembly for the next charge. The use of a fabric bag (30) also makes it possible to use a large mesh support screen 28', since the wall material of the bag 30 performs the function of screening and retaining the solid materials.

There are no sharply defined conditions of temperature and pressure required to make the method work. However, temperatures below 60"C and pressures below 500 psig are not satisfactory from the standpoint of yield and production rate.

The upper limit of pressure is determined only by the capability of the press. However, pressures above 5000 psig (34.2 MPa) on the lupulin powder gave only a slightly higher yield of concentrate.

Temperatures above 65" reduce the viscosity of the resin and therefore reduce the time required for pressing. However, hop flavors are known to be sensitive to heat and for this reason extremely high temperatures should be avoided.

The method of the present invention will be further described by reference to the following examples: Example I A press cylinder was used having an internal chamber diameter of 85 mm and a height of 193 mm. A screen 28 was used which had openings measuring about 0.125 mm across. A charge of 140 grams of lupulin powder having an alpha acid content of about 45.5wt% was weighed out and warmed in an oven to approximately 65"C. The press assembly was also heated to approximately 65"C.

The heated lupulin powder was then poured into the cylinder 10, onto the screen 28. Then the piston 16 was inserted and the assembly was placed between the plattens of a conventional hydraulic press. The press was operated to force the piston 16 against the lupulin powder. Liquid concentrate began flowing out through the outlet opening 32 when the applied pressure on the lupulin powder reached about 500 psig (3.42 MPa). The pressure was progressively increased over a period of fiteen minutes to the maximum capability of the press which was about 5,000 psig (34.2 MPa) on the lupulin powder.

Ninety-five grams of liquid concentrate was collected and it had an alpha acid content of 55.2 wt%. This represented a yield of 82% of the total alpha acid available in the lupulin powder.

The liquid concentrate was light brown in color and possessed a pleasing aroma of natural hops. It became very viscous at room temperature (20 - 25"C) but liquified readily upon being heated to approximately 60"C.

The press cake that was produced weighed 45 grams and had an alpha acid content of 23.8 wt%.

Example II A charge of 140 grams of lupulin powder was placed into a Nylon bag and the Nylon bag was placed in the cylinder on top of a coarse mesh screen 28' having mesh openings of approximately 0.34 mm across. The Nylon fabric had mesh openings of approximately 0.07 mm across.

The lupulin powder charge and the press components were all preheated to approximately 65"C.

The piston 16 was moved against the bag and the pressure progressively increased over a period of fifteen minutes to the maximum capacity of the press, the same as was done in connection with Example I. The 140 grams of lupulin powder, having an alpha acid content of about 45 wt%, yielded 92.8 grams of liquid concentrate, having an alpha acid content of 53.6 wt%. This was a yield of 79% of the available alpha acid.

Example 111 In this Example, a lower grade of lupulin powder was used, having an alpha acid content of about 35 wt%. the lower alpha acid content was due to the presence of finely divided green fibrous vegetable matter from the broken bracts of the hop cone.

One hundred grams of this lower grade of lupu- lin powder was heated to about 65"C and placed in a canvas bag. The bag was placed in the heated cylinder 10, on a base screen 28 having a mesh opening of 0.34 mm square. A heated piston 16 was inserted into the cylinder 10 and the assembly was placed in a hydraulic press. Pressure was applied and was gradually increased to about 3,000 psig (20.5 MPa) on the lupulin powder, expressing liquid concentrate through the wall of the canvas bag. The size of the mesh openings in the canvas was not determined. However, the bag retained the solids, indicating that the mesh size was small enough.

The weight of the press cake was about 36.4 grams, showing that about 63.6 grams of resin had been expressed. The press cake contained about 14.4 wt% alpha acid, corresponding to about 5.24 grams of alpha acid in the press cake out of the original 35 grams of alpha acid. The calculated recovery of alpha acid in the liquid concentrate was about 85%.

Example IV In this run, the lupulin powder used was quite low grade; it contained only 30.2 wt% alpha acid.

A charge of 100 grams of lupulin powder was weighed out and placed into a Nylon bag of the type used in Example II. The alpha acid content of this charge was about 30.2 grams. The bag and its contents and the press cylinder and the piston were all heated to about 65"C. The bag was placed into the cylinder 10, the piston 16 (preheated to 65"C) was inserted, and the assembly was placed between the plattens of a hydraulic press. The press was operated to gradually increase the pressure on the lupulin powder charge up to the pressure of about 2,500 psig (17.1 MPa).

The press cake weighed about 56 grams and had an alpha acid content of about 8.5 wt%. This computed to be a residual of about 4.8 grams of alpha acid that was left in the press cake. The quantity of alpha acid in the expressed liquid concentrate calculated to be about 25.4 grams, representing 84% of the alpha acid in the original charge The liquid concentrate had a light brown color and the pleasant aroma of natural hops.

In accordance with the present invention, the press cakes removed from the press cylinder 10 could be further processed by use of the known solvent extraction method. As previousiy mentioned, if solvent extraction is used to recover additional alpha acid from the press cakes, the product of this secondary phase method is kept separate from the product produced by mechanical separation in the press and is sold into markets which will accept a liquid concentrate which includes small amounts of solvent residue.

It will be readily apparent to those skilled in the art that many modifications can be made in the method steps and/or apparatus used without departing from the invention that is defined by the appended claims.

Claims (27)

1. A method of separating flavor resins and oils from hop lupulin powder, comprising: heating a quantity of hop lupulin powder to melt resins contained therein; applying pressure to the heated hop lupulin powder to rupture the lupulin and to express therefrom a viscous liquid concentrate of hop flavor resins and essential oils, substantially free of cellular material, and at the same time produce a residue press cake comprising cellular material; and separating the viscous liquid concentrate from the press cake material.

2. A method according to Claim 1, comprising expressing the viscous liquid concentrate through a wall of material which is permeable to the viscous liquid concentrate but not to the press cake.

3. A method according to Claim 2, comprising expressing the viscous liquid concentrate through openings in a screen which are smaller in size than intact lupulin glands, so that the cellular material will be retained on the screen, to in this manner form the press cake and separate the viscous liquid from the press cake.

4. A method according to Claim 1, comprising placing the heated hop lupulin into a bag constructed from a fabric material that is permeable to the viscous liquid concentrate but not to the press cake material, supporting the bag on a permeable screen, and applying pressure to the bag to in that manner express viscous liquid concentrate out from the heated hop lupulin, through the bag wall material, while retaining the press cake within the bag.

5. A method as claimed in Claim 4 wherein the screen has openings larger than intact lupulin glands.

6. A method according to any one of Claims 3 to 5 comprising supporting the screen on a surface which includes channels into which the separated viscous liquid concentrate flows as it is being expressed from the heated hop lupulin through the screen openings.

7. A method according to Claim 6, wherein the surface supporting the screen is the inner surface of an end closure member of a cylinder into which the heated hop lupulin is placed and a piston is inserted into the cylinder and used to apply pressure to the heated hop lupulin.

8. A method according to Claim 7 wherein the channels lead to a collection opening.

9. A method according to Claim 7 or Claim 8, comprising heating both the cylinder and the piston so that they will keep the lupulin warm.

10. A method according to any one of the preceding claims, comprising extracting additional hop flavor constituents from the press cake by use of a solvent.

11. A method according to any one of the preceding claims, comprising using hop lupulin mixed with finely divided green fibrous vegetable matter from broken hop cone bracts, and collecting said fibrous vegetable matter in the press cake.

12. A method of separating flavor resins and oils from hop lupulin, comprising: preheating a quantity of hop lupulin to melt resins contained therein; applying pressure to the heated hop lupulin by use of heated press apparatus, to express therefrom a viscous liquid concentrate of hop flavor resins and oils which is substantially free of cellular material, and at the same time produce a residue press cake comprising cellular material; and separating the viscous liquid concentrate from the press cake by flowing the viscous liquid concentrate away from the press cake as the pressure is being applied.

13. A method according to Claim 12, comprising expressing the viscous liquid concentrate through a wall means which is permeable to the viscous liquid concentrate but not to the press cake material.

14. A method according to Claim 12, wherein the wall means comprises a screen having openings which are smaller than intact hop lupulin glands, so that the cellular material will be retained on the screen, to in this manner form the press cake and separate the viscous liquid from the press cake.

15. A method according to Claim 13 wherein the wall means comprises a bag into which the heated hop lupulin is placed and which is constructed from a fabric material that is permeable to the viscous liquid concentrate but not to the press cake material, the bag is supported on a screen having openings bigger than intact lupulin glands, and pressure is applied to the bag to express viscous liquid concentrate out from the heated hop lupulin, through the bag wall material, while retaining the press cake within the bag.

16. A method according to Claim 14 or Claim 15, comprising supporting the screen on a surface which includes channels into which the separated viscous liquid concentrate flows as it is being expressed from the heated hop lupulin through the screen openings.

17. A method according to any one of Claim 12 to 16, comprising extracting additional hop flavor constituents from the press cake by use of a solvent.

18. A method fo separating flavor resins and oils from hop lupulin substantially as hereinbefore described with reference to the accompanying drawings.

19. Apparatus for expressing flavor resins and oils from hop lupulin which has been preheated to melt resins contained therein, comprising: a cylinder having an open end and an end closure end member at the opposite end, the end closure member having an inner surface formed to include a pattern of channels leading toward a collection opening; a screen member overlaying the channels; the cylinder including a discharge opening in communication with the channels; and a piston insertable into the cylinder, whereby in use the piston and cylinder are preheated and preheated hop lupulin is placed between the screen and the piston and the piston is moved toward the screen to express a viscous liquid concentrate of hop flavor resins and oils from the lupulin which is substantially free of cellular material, and at the same time producing a residue press cake comprising cellular material.

20. Apparatus according to Claim 19, comprising a screen having openings therein which are smaller in size than intact lupulin glands, whereby in use the hop lupulin is placed on the screen and the screen is used for collecting the press cake material and causing the viscous liquid concentrate to be separated from the cake material.

21. Apparatus according to Claim 19, comprising a bag made of wall material which is permeable to the viscous liquid concentrate but not to the press cake material, into which the heated hop lupulin is placed, and which then is placed on the screen and against which the piston is moved, whereby when the piston is moved against the bag the hop lupulin is pressed and the flavor resins and oils are expressed out from the heated hop lupulin, through the bag wall material, through the screen openings, and into the channels and from the channels into the discharge opening.

22. Apparatus according to any one of Claims 19 to 21, wherein the end closure for the cylinder is removably insertable into the cylinder, and the apparatus further includes seal means for sealing bnetween the end closure member and the cylinder.

23. Apparatus according to Claim 22, wherein the end closure member includes a sidewall opening in communication with the channels, and the cylinder includes a sidewall opening in the end closure member, when the end closure member is in place within the cylinder.

24. Apparatus for expressing flavor resins and oils from heated hop lupulin substantially as hereinbefore described with reference to the accompanying drawings.

25. Hop lupulin concentrate whenever prepared by a method according to any one of Claims 1 to 18 or by using an apparatus according to any one of Claims 19 to 24.

26. A method of brewing which comprises a method according to any one of Claims 1 to 18, the use of apparatus according any one of Claims 19 to 24 or the use of hop lupulin concentrate according to Claim 25.

27. A beverage whenever brewed by a method according to Claim 26.