NOVEL APPLICATIONS OF HOP ACIDS

Abstract

The present invention relates to novel applications of hop acids and formulations using hop acids. More specifically, the present invention relates to formulations comprising hop acids to stabilise or emulsify hop oils or other essential oils in aqueous media. We describe an aqueous emulsifiable composition comprising 0.01-5.00 wt % of at least one essential oil and 0.005-10.0 wt % of at least one hop acid, the balance being water. We also describe a method of stabilising or emulsifying an essential oil or mixture of essential oils. The method comprises mixing the essential oil or mixture of essential oils with at least one hop acid to form an essential oil and hop acid mixture and mixing the essential oil and hop acid mixture with water. We further describe the use, as an emulsifier, of a composition comprising at least one hop acid and beverages obtainable with the composition.

Claims

1. An aqueous emulsifiable composition comprising 0.01-5.00 wt % of at least one essential oil and 0.005-10.0 wt % of at least one hop acid, the balance being water.

2. A composition as claimed in claim 1 wherein the at least one hop acid is at least one hop beta acid, hop alpha acid, iso-alpha acid, rho-iso-alpha acid, tetrahydro-iso-alpha acid, hexahydro-iso-alpha acid, hexahydro-iso-beta acid, hulupone or humulinone or a mixture or mixtures thereof.

3. A composition as claimed in claim 2 wherein the at least one hop acid is at least one hop beta acid.

4. A composition as claimed in any preceding claim wherein the at least one hop acid is at least one hop acid salt, preferably a monovalent salt, more preferably a potassium salt or a sodium salt, most preferably a potassium salt.

5. A composition as claimed in any preceding claim wherein the at least one hop acid or hop acid salt is at least one isolated or purified hop acid or hop acid salt.

6. A composition as claimed in any preceding claim wherein the at least one essential oil is at least one hop essential oil, or at least one fruit essential oil, at least one flower essential oil, at least one seed essential oil, or mixture or mixtures thereof.

7. A composition as claimed in any preceding claim wherein the composition has a hop acid content and total essential oil content in a ratio of about 1:5 to about 5:1; preferably in a ratio of about 1:2 to about 2:1.

8. A composition as claimed in any preceding claim wherein the composition is formed by mixing the at least one hop acid and the at least one essential oil; and combining the mixture with water.

9. A composition as claimed in any preceding claim wherein the composition has an essential oil content of up to about 2 wt %; or up to about 1 wt %.

10. A composition as claimed in any preceding claim wherein the composition has an essential oil content of from 0.1 wt % to 1 wt %.

11. A composition as claimed in any preceding claim wherein the composition has a hop acid content of about 0.01 wt % or more, or about 0.05 wt % or more.

12. A composition as claimed in any preceding claim wherein the composition has a hop acid content of up to about 5 wt % or up to about 2 wt %.

13. A composition as claimed in any preceding claim wherein the composition has a hop acid content of 0.05 wt % to 2 wt %.

14. A method of stabilising or emulsifying an essential oil or mixture of essential oils, the method comprising the step of mixing the essential oil or mixture of essential oils with at least one hop acid to form an essential oil and hop acid mixture and mixing the essential oil and hop acid mixture with water.

15. A method as claimed in claim 14, wherein the hop acid is hop beta acid, hop alpha acid, iso-alpha acid, rho-iso-alpha acid, tetrahydro-iso-alpha acid, hexahydro-iso-alpha acid, hexahydro-beta acid, hulupone, humulinone or a mixture thereof.

16. A method as claimed in claim 15 wherein the hop acid is hop beta acid.

17. A method as claimed in any one of claims 14 to 16 wherein the hop acid salt is a monovalent salt, preferably a potassium salt or a sodium salt, more preferably a potassium salt.

18. A method as claimed in any one of claims 14 to 17 wherein the hop acid or hop acid salt is an isolated hop acid or hop acid salt.

19. A method as claimed in any one of claims 14 to 18 wherein the at least one essential oil is at least one hop essential oil, or at least one fruit essential oil, at least one flower essential oil, at least one seed essential oil, or mixture or mixtures thereof.

20. A method as claimed in any one of claims 14 to 19 wherein the hop acid and essential oils are mixed in a ratio of about 1:5 to about 5:1; preferably in a ratio of about 1:2 to about 2:1.

21. A method as claimed in any one of claims 14 to 20 wherein the essential oil or mixture of essential oils, the hop acid or mixture of hop acids and water are mixed to provide an essential oil content of up to about 5 wt %, preferably up to about 2 wt %, more preferably up to about 1%.

22. A method as claimed in any one of claims 14 to 21 wherein the essential oil or mixture of essential oils, the hop acid or mixture of hop acids and water are mixed to provide a hop acid content of about 0.01 wt % or more or about 0.05 wt % or more.

23. A method as claimed in any one of claims 14 to 22 further comprising the step of shear mixing the mixture or high-pressure homogenisation of the mixture, preferably, high-pressure homogenisation.

24. Use, as an emulsifier, of a composition comprising at least one hop acid.

25. Use as claimed in claim 24 wherein the at least one hop acid is hop beta acid, hop alpha acid, iso-alpha acid, rho-iso-alpha acid, tetrahydro-iso-alpha acid, hexahydro-iso-alpha acid, hexahydro-beta acid, hulupone, humulinone or a mixture thereof, preferably wherein the hop acid is hop beta acid.

26. Use as claimed in claim 24 or claim 25 wherein the hop acid is a hop acid salt, preferably a monovalent salt, more preferably a potassium salt or a sodium salt, most preferably a potassium salt.

27. Use as claimed in any one of claims 24 to 26 wherein the hop acid or hop acid salt is an isolated or purified hop acid or hop acid salt.

28. Use as claimed in any one of claims 24 to 27 in the emulsification in water of at least one essential oil.

29. A method of flavouring a beverage, the method comprising mixing a composition as claimed in any one of claims 1 to 13 with a beverage.

30. A method as claimed in claim 29 wherein the beverage has an alcohol content of 10% ABV or lower, 5% ABV or lower, 1.2% ABV or lower; 1.0% ABV or lower; 0.5% ABV or lower; 0.1% ABV or lower; or 0.05% ABV or lower.

31. A method as claimed in claim 29 or claim 30 wherein the beverage is a beer.

32. A method as claimed in claim 31 wherein the composition is mixed with the beverage during or at the end of the beer brewing process.

33. A beverage obtained by the method of any one of claims 29 to 32.

Description

ASSESSMENT OF FORMULATION STABILITY

[0070] FIG. 1 shows the stability of aqueous whole oil formulations (based on the preparations in Examples 13 to 16) after 35, 105 and 360 days.

[0071] FIG. 2 shows the stability results of the aqueous solutions of fractionated oil formulations (based on Examples 3, 6 and 9 with 0.1% KBA and Examples 4, 7 and 10 with 0.05% KBA) after 48, 99 and 239 days.

[0072] FIG. 3 shows the stability results of the aqueous solutions of fractionated oil formulations (based on Examples 5, 8 and 11 with 0.2% KBR) after 35, 105 and 360 days.

[0073] FIG. 4 shows the stability results of aqueous formulations under different mixing. The term ‘shear mixed’ denote formulations which were shear mixed at 24,000 rpm, but not high pressure homogenised. ‘10×10K psi’ denotes formulations homogenised by 10 passes at 10,000 psi (69 MPa). ‘10×25K psi’ denotes formulations homogenised by 10 passes at 25,000 psi (172 MPa).

[0074] The stability was assessed by the following scale: 5—No visible separation, 4—very slight separation, 3—slight separation, 2—some separation, 1—significant separation.

[0075] FIG. 1 demonstrates the stability of the whole oil formulations after 35, 105 and 360 days. Very good stability is seen.

[0076] FIGS. 2 and 3 demonstrate that the fractionated oil formulations with both KBR and KBA, have even better stability. FIG. 4 shows the benefit of high-pressure homogenization. Shear mixed samples did show some separation of the hop oil but can be rapidly re-mixed simply by shaking.

[0077] Table 4 below shows the stability of formulations made using Example 20 of varying oil concentration (note: samples were not high pressure homogenised).

TABLE-US-00005 TABLE 4 Oil Potassium hop beta Stability concentration acid concentration 3 days 70 days 10% w/w 10% w/w 1 1 1% w/w 1% w/w 4 3 0.5% w/w 0.5% w/w 5 4 0.1% w/w 0.1% w/w 5 4 0.05% w/w 0.05% w/w 5 5 0.01% w/w 0.01% w/w 5 5

[0078] Table 5 below shows the stability of formulations made using Examples 21 to 23 of varying oil types and concentration (note: samples were not high pressure homogenised).

TABLE-US-00006 TABLE 5 Stability of oil formulation after 74 days Hydro- Potassium distilled hop beta Target hop Lemon Peppermint Oil acid oil oil oil concen- concen- Example Example Example tration tration 21 22 23 5% w/w 5% w/w 1 1 1 2% w/w 2% w/w 2 2 1 1% w/w 1% w/w 3 3 2 0.5% w/w 0.5% w/w 4 3 2 0.1% w/w 0.1% w/w 4 4 3 0.05% w/w 0.05% w/w 4 4 4 0.01% w/w 0.01% w/w 5 4 4

Density of Potassium Hop Resin and Essential Oils

[0079] The density of the essential oils and the hop acid salts was assessed, and the results are shown in Table 6 below.

TABLE-US-00007 TABLE 6 Component Density - g/ml at 25° C. HD Target hop oil 0.92 MD Target hop oil 0.91 SD Target hop oil 0.86 Spicy fraction 1.17 Citrussy fraction 0.98 Floral fraction 0.92 Late hop floral fraction 0.93 Orange oil 0.85 Potassium beta acid resin 1.09 Potassium iso-alpha acid resin 1.15

[0080] Table 7 below shows the stability of formulations made using Examples 27 with varying ratios of oil and KBR (note: samples were not high pressure homogenised).

TABLE-US-00008 TABLE 7 Ratio Calculated Stability of formulation of oil density of 5 days 37 days to KBR mixture 1% oil 0.1% oil 1% oil 0.1% oil 5:1 0.90 1 1 1 1 2:1 0.94 1 1 1 1 1:1 0.97 2 4 1 4 1:2 1.01 3 5 3 4 1:5 1.05 4 4 2 4

[0081] It was observed that the optimum formulations arise when the combined density of the hop acid and oil are similar to the density of the water so that the oil remains in suspension and does not tend to rise or cream to the top or sediment on the bottom. This suggests that the hop acids may be acting as weighting agents, as well as or rather than emulsifiers.

Other Hop Acids

[0082] The use of other hop acid salts was assessed, and the results shown in Table 8.

TABLE-US-00009 TABLE 8 Hop Acid Stability Formulation (potassium salt) 19 days 210 days Example 17 Alpha acid 4 2 Example 18 Iso-alpha acid 3 1 Example 19 Beta acid 4 3

[0083] It was observed that all hop acids improve the stability of the formulations although hop beta acids show optimum effectiveness.

Flavoured Drinks

[0084] Table 9 shows that aqueous hop beta acid and essential oil formulations containing sugar show good stability.

TABLE-US-00010 TABLE 9 Lemon Syrup Sugar Oil Hop beta acid Stability Formulation concentration concentration concentration 14 days Example 28 50% 100 ppm 50 ppm 4 Example 29 50% 500 ppm 250 ppm 5 Example 30 50% 100 ppm 0 ppm 1 Example 31 50% 500 ppm 0 ppm 2

[0085] When these syrups were added to still or sparkling water, sweet, lemon-flavoured drinks were produced (Example 32).

Hop Beta Acids in Salts and Free Acid Form.

[0086] The use of hop beta acids as different salts (sodium and potassium) and in their free acid form was assessed and the results shown in Table 10.

TABLE-US-00011 TABLE 10 Formulation Hop beta Acid used Stability 3 days Example 34 KBA 4 Example 35 NaBA 4 Example 36 Hop beta acid crystals 2 Example 37 None 1

[0087] It was observed that best stability was formulations with hop beta acids in their salt form, rather than their free acid form. As expected, if no hop beta acids were added to the formulation, the oil rapidly separated from the water.

DISCUSSION

[0088] From our work, we have determined that hop acids (optimally in their salt form) can stabilise hop oils and other essential oils in aqueous formulations. The formulations disperse well and have excellent stability.

[0089] The formulations are made by mixing the hop or other essential oil and potassium hop beta acid resin and then mixing vigorously into water. Stability can be enhanced by high-pressure homogenisation of the aqueous formulation. The formulations are typically cloudy in appearance. Optimum formulations show good stability at least up to six months. Even at high oil concentrations of 5 wt %, if separation does occur, a brief shake by hand readily restores a uniform emulsion.

[0090] The hop acids may be acting solely as emulsifiers (ie., they have a polar portion to solubilise in water and lipophilic portion to solubilise oil). However, when added to water, the potassium hop beta acids would be expected to form mainly the free acid and hence be water-insoluble (pKa-ca. 5.5-7.8) under the acidic or neutral pH conditions of certain essential oil preparations. Accordingly, we hypothesise that the hop beta acids potentially may alternatively or additionally be acting as weighting agents. Hop oils typically have density of 0.8-0.9 g/ml and potassium hop beta acids have density of ca. 1.1 g/ml. By mixing the acids with oil, the resultant droplets could be expected to have similar densities to water, thereby being less prone to creaming.

[0091] Hop acids found to be suitable in this work include hop beta acids (lupulones), hop alpha acids (humulones), iso-alpha acids (iso-humulones), rho-iso-alpha acids (rho-iso-humulones), tetrahydro-iso-alpha acids (tetrahydro-iso-humulones), hexahydro-iso-alpha acids (hexahydro-iso-humulones), hexahydro-beta acids (hexahydro-lupulones), hulupones, humulinones, including co, n, ad homologues, isomers (e.g. cis/trans), stereoisomers (R and S) and mixtures thereof. Preferred formulations use beta acids, but other hop acids such as alpha acids, iso-alpha acids and tetrahydroiso-alpha acids also show good properties.

[0092] From our work, it appears that any essential oil is suitable for formulation in accordance with the present invention. The invention is particularly useful for food and drink applications using essential oils such as: hop, orange, lemon, lavender, oregano. The essential oils may be whole hop oils (e.g. steam distilled (SD), molecular distilled (MD), hydro-distilled (HD)) or fractionated hop oils (e.g. spicy, citrussy, floral, late hop floral fractions), as required, having regard to the intended purpose of the essential oil. For example, the formulations can be used to dose hop oil formulations in the brewing process—ideally at end of the process—to the final bright beer or to dose citrus essential oils into fruit-based drinks.

[0093] Accordingly, the present invention also provides methods of flavouring beverages by mixing an inventive composition with a beverage; and beverages obtainable by this method. The compositions of the present invention are useful in flavouring low alcohol beverages, such as beers having an alcohol content of 1.2% ABV or lower; 1.0% ABV or lower; 0.5% ABV or lower; 0.1% ABV or lower; or 0.05% ABV or lower.

[0094] Additional components, such as thickening agents, e.g. Xanthan gum can be added.

[0095] In the context of brewing beer, since hop alpha acids and hop beta acids are already commonly present in beer, by applying the methods and compositions of the present invention, it is not necessary to use ethanol or propylene glycol, or other synthetic emulsifiers. Hitherto, there have been very few natural emulsifiers available for food use, hence this application has a broad scope not only in beer, but for many other food and drink formulations.

[0096] Additionally, hop acids have antimicrobial activity, so will tend to protect the aqueous formulations from micro-contamination. No bacterial, yeast or mould growth was seen in any unopened samples, even after extended periods of storage, such as twelve months or more. This demonstrates that products prepared with compositions of the present invention have good shelf-life.

[0097] Taste testing trials have shown that, when formulations are added to beer, the flavour or aroma of the hop oil are released into the beer. Hop beta acids themselves have very little taste impact and so will not give any negative effect on aroma or flavour of the final beer in the amounts resulting from use of the compositions of the present invention. Other hop acids are bitter, but the amount added by the formulations of the present invention are sufficiently low that the amount of hop acid will not significantly affect taste of final product. For example, iso-alpha acids have a taste threshold in beer of a few ppm whereas the taste threshold for hop essential oils is typically in terms of parts per billion. Typically, beer contains 10-100 ppm iso-hop alpha acid for bitterness. Accordingly, in the context of the preferred formulations in which the ratio of hop oil to hop acid salt is in the range of 1:2 to 2:1, the addition of 400 ppb of hop oil to a beer will only add an additional 200-800 ppb of iso-hop alpha acids and will therefore have a negligible or no impact on the taste of the beer.

[0098] Additionally, the emulsification properties of hop acids can not only be exploited for essential oils, but may be used to stabilise other oil/water-based mixtures. For instance, with food and beverages, the hop acids can be used to emulsify any oil soluble components such as flavours, colours, antioxidants and vitamins. Similarly, in cosmetic and personal care products, the hop acids can be used to emulsify water insoluble components such as flavours, colours, aromas and active ingredients. Additionally, the hop acids may be used to emulsify certain water-insoluble active ingredients in pharmaceutical compositions.