WO1994000551A1

WO1994000551A1 - Process for altering flavour of food products

Info

Publication number: WO1994000551A1
Application number: PCT/NZ1993/000053
Authority: WO
Inventors: Warwick Murrow Jameson
Original assignee: The Anchor Brewing Company (Nz) Ltd.
Priority date: 1992-06-25
Filing date: 1993-06-24
Publication date: 1994-01-06
Also published as: ZA934524B; CN1083522A; AU4361693A; NZ243303A

Abstract

Flavours in food products can be enhanced by the addition of ethene. In particular, ethene can be added to essential oils from hops to enhance the flavour in beer. Ethene may be combined with carbon dioxide and/or water. Ethene can also be added to yeast to reduce glucose repression and thereby enhance formation of desirable flavours.

Description

PROCESS FOR ALTERING FLAVOUR OF FOOD PRODUCTS

Technical Field

The invention relates to a process for enhancing flavours in food products and, in particular, to a process for producing a pleasant aroma in beer-

It is to be understood that the term flavour as used throughout this specification includes aroma and taste.

The term "food product" as used throughout this specification includes any solid or liquid consumed by man. In industry, ethene is often referred to as "ethylene".

Background of Invention

A fine hop aroma and hop taste in beer is indicative of quality and these attributes are sought by both brewer and beer drinker. In the beer industry, a number of processes are used to produce beer which has a pleasant aroma.

One method of producing this "hoppy" aroma is called "late copper hopping". This involves adding extra hops to the wort. Another method is dry hopping.

This involves adding selected hops to conditioning beer.

Unfortunately, a relatively long contact time between the beer and the hops is needed. Finally, hop oil may be extracted from hops and added directly to the beer.

These methods of producing a hop aroma have known disadvantages. Instilling a hop aroma flavour into beer via late copper hopping or standard dry hopping method is difficult and often unpredictable in its end result.

Also such processes often contribute little to increasing the flavour in the final product. The flavours are diminished during fermentation and the hop flavour which is produced in the final product is not strong. Extracts of essential oils of hops, prepared using liquid carbon dioxide are available, but are costly. Also they impart little aroma. A stronger hop aroma would be more pleasing to the beer consumer.

Disclosure of the Invention

It is therefore an object of the invention to overcome at least some of the problems outlined above or at least to provide the public with a useful choice.

The applicant has surprisingly found that ethene can be used to enhance the flavour of food products. Surprisingly, when ethene is mixed with a liquid, the resulting ethene/liquid mixture can subsequently be used to enhance the flavour of substances. In particular, the applicant has surprisingly found that when ethene is mixed with a liquid, and this gas-containing liquid is added to beer or beer about to be fermented, a better flavour is produced in the final product, particularly a better hop flavour. It is thought the ethene cross- links with essential oils from hops bringing about a transesterification.

The invention provides a method of adding flavour to food products comprising combining ethene with a food product other than by way of contacting the food product with ethene and holding the food product in a gaseous atmosphere at normal atmospheric pressure.

The invention further provides a method of adding flavour to food products comprising combining ethene in a mixture together with a solid, liquid or gas or combination thereof with a food product.

The invention further provides a method of adding flavour to food products comprising combining ethene with a flavouring substance and adding the resulting combination to the food product.

In a preferred embodiment, ethene is combined with a liquid such as water and the resulting product is combined with a flavouring substance or a flavouring ingredient. The resulting composition may then be added to a food product sought to be flavoured.

Preferably the food product is beer. Preferably the flavouring substance or ingredient is extracted oils. Preferably these are derived from hops.

Preferably a gas is used together with the ethene. This gas is preferably carbon dioxide (but it may be nitrogen or oxygen or a mixture of these gases). Carbon dioxide may help render the ethene non flammable, allow easier metering of gas and prevent over exposure of ethene (technically known as gas burn) .

Alternatively or in addition,^' the gas may act as a suitable carrier to get ethene into solution. Preferably the ethene is present in a lower concentration than the gas. The preferred ratio of ethene to carbon dioxide is dependent on the nature of the food ingredient or product being processed. A desirable ratio for beer may be 25% ethene to 75% carbon dioxide (by volume).

Preferably the ethene or mixture of ethene and gas such as carbon dioxide is added to water and the water/ ethene or water/ethene/gas mixture is added to the flavouring substance. The ratio of water to ethene or water to ethene plus carbon dioxide may be 1:1 (vol/ vol) . However, any ratio of water to gas mixture which is sufficient to achieve the desired result is envisaged. This may be determined for any particular food product, or flavouring substance.

Preferably the resulting blend of ethene, carbon dioxide, water and flavouring substance is added to beer for hop flavour, more preferably to chilled beer which is held at the pre-filtration stage.

Non-isomerised hop extract may be used instead of hops. The extract may contain chlorophyll. Without attempting to explain a mechanism, the chlorophyll may assist in the flavour enhancement of the invention in relation to beer production. Commercially prepared hop oils or essences may be used as an addition to hops or hop extracts. Preferably, good quality hops, low in sulphur and free from oxidation are used. It is preferred that the beer which is subject to the process is substantially phenol free.

Preferably essential oils are extracted from hops which are at a stage of growth such that the bulk of the essential oils are still intact. Properly stored and packaged compressed whole-cone hops are suitable. About 80g hops/hectolitre of beer may be suitable. Essential hop oils may be obtained from hops by washing with a suitable solvent such as an alcohol, eg ethanol, preferably 95% ethanol. The ethanol may be acidified with phosphoric acid to further enhance the formation of esters within the hops. The alcohol solvent may be stripped from the hops using chilled demineralised, acidified water to obtain oils, resins and chlorophyll. Preferably the hop:ethanol ratio is lkg:41itres (wt/vol) . Preferably the recovered wash is kept chilled.

Preferably the carbon dioxide/ethene mix is trickled in to the water via the suction side of a centrifugal pump set up to recirculate the water being treated. Preferably the hop wash is then added with a recirculating pump or high speed stirrer to ensure adequate mixing. Desired quantities of the wash which form an emulsion may be added to chilled beer.

Alternatively, the ethene may be added with carbon dioxide at the carbonation stage of beer production.

As a further alternative, a continuous feed of ethene/C0₂ may be added to recirculating beer itself rather than adding more water if addition of dilution water to beer is not required.

The invention also provides a flavouring composition comprising ethene together with a flavouring substance. Preferably the flavouring substance is hops or essential oils from hops-.

The invention also provides a food product when prepared by the above methods. The invention also contemplates flavour modification in fermented food products.

A limiting factor in yeast fermentation is the inability of some yeasts to tolerate high levels of certain sugars, in particular glucose. At glucose levels of above 0.4% w/v, fermentation may reduce due to a phenomenon known variously as glucose repression, catabolite repression or osmotic shock. The applicant believes without wishing to be bound by any theory, that this phenomenon can be reduced by mixing ethene with a liquid and then adding this ethene/liquid mixture to yeast.

The applicant has therefore developed a process which reduces the phenomenon allowing fermentation to proceed and allowing yeast to add flavour to the fermentable medium. The process also allows fermentations to proceed from very high starting densities of sugar solution (specific gravities 1.080+) whilst allowing a marked reduction in yeast requirement. Greater quantities of liquid can be fermented as a concentrate in the same sized storage vessel capacity.

The applicant believes ethene reduces the phenomenon of glucose repression in yeast and therefore enhances favourable development of flavours such as alcohol, hence the flavour of fermented foods is improved.

Hence, in another aspect, the invention provides a method for contacting yeast with ethene, comprising the steps of mixing ethene into a medium suitable for subsequent contact with yeast. Preferably the ethene is added directly to wort. However, the ethene could be added to a liquid such as water and the resulting combination added to a medium to be fermented after which yeast is added.

Preferably ethene is mixed with carbon dioxide.

Preferably ethene and carbon dioxide are dissolved into the wort. This may be via the wort cooling heat exchanger or at any point that ensures enough turbulence to dissolve the gases into the wort. Preferably there is a higher ratio of carbon dioxide than ethene in the ethene/carbon dioxide mix. A ratio of 25% ethene, 75% carbon dioxide (vol/vol) is preferred initially. However, subsequent ratios may be determined on the basis of dissolvability in the liquid using any particular gas/liquid mixer.

The carbon dioxide may be useful in helping the flavouring substance or ingredient to respire if, for example, the flavouring substance is yeast. The carbon dioxide may reduce the pH of the mixture.

Alternatively, the medium to be fermented may be fruit or vegetable juices and thus ethene (or ethene and carbon dioxide) may be added to juice prior to fermentation or to during fermentation. The ethene may be added to the transfer line between bulk holding and the fermentation method.

The amount of ethene added may be dependent upon the particular strain of yeast used, the specific gravity of the medium its content of catabolite repressing sugars and the stimulatory effect required. The invention also contemplates use of ethene to enhance flavouring in dairy products. With dairy products, it can be used with D-galactose or in cheeses that are made utilising moulds or fungi that have a carboxylic cycle in their respiratory system.

The process as disclosed herein may also be used in the baking industry, to enhance yields of yeast in the propagation of bakers or brewers yeast for commercial sale. The process may also be used to stimulate yeast which has been stored wet or dry for lengthy times. The process may go some way in reducing or eliminating the osmotic shock in yeast when it is added to a high gravity solution. By "osmotic shock" is meant glucose repression and catabolite repression. The process may go some way in reducing the lag phase in yeast multiplication and thus help enhance sporulation. It may also help reduce the risk of bacterial infection, speed up the fermentation and increase yeast yield.

An additional advantage of adding carbon dioxide with the ethene is that the yeast may be able to fix carbon from the carbon dioxide.

It will be appreciated from the above description and from the specific embodiments that surprising advantages can be obtained from the use of ethene to enhance flavour in food products.

In particular, use of the invention allows a brewer to abandon the unreliable and unpredictable methods of attempting to instil hop aroma into beer. Embodiments of the invention are now described by way of example only which describe flavour enhancement in beer.

Best mode for carrying out the invention

Example 1

Use of Ethene for Processing Hops and Extracts and Oils Thereof

Malt phenol, if carried through the beer process to react with hop chlorophyll, may result in a "medicinal" taste in the beer. To reduce this, up to 0.0083% v/w malt grist of 100% hydrogen peroxide is added to the mashing liquor to stimulate malt peroxidase and retain the phenols within the grist.

Oxygen pick-up during lautering must be avoided. Care must be taken to avoid hot wort splashing and air entrainment from the suction side of any wort transfer pumps. This includes recycling wort for clarification. This is because ethene appears to have an affinity for oxygenated components of wort as well as for oxygen itself. Later addition of ethene may amplify the unwanted tastes of oxygenated components and disrupt the action of ethene on hop oils. It is important steps are taken to avoid any oxygen pick-up from the fermenter stage, including pick-up during finings manufacture and addition.

Preparation of An Emulsion of Hop Oils

Hops from which oils are extracted should be of good quality, free from oxidisation. Properly stored and packaged whole-cone hops are well suited to the process. About 80g hops/hectolitre of beer has been found desirable.

The solvent used is food grade ethanol 95% at 4mls/gram of hops. This amount will saturate the hops without leaving a surplus. Prior to addition, the ethanol should be acidified with phosphoric acid to at least pH4. This further enhances the formation of esters within the hops. The acidified ethanol is added to and mixed into the hops and left for a period to ensure total absorption of the alcohol and formation of added esters.

Stripping of Oils From the Hops Small Scale

Demineralised, de-chlorinated water is acidified with phosphoric acid to at least pH4 and chilled. It is added and mixed well with the hops to wash out the oils. In the first wash, the same amount of water is added as ethanol. For example, 4 litres of ethanol are added to 1 kg of hops then 4 litres of chilled water is mixed in. The resultant emulsion is drained off via a sieve then another 4 litres of chilled water is mixed in and the process repeated. Around 3 to 4 washes will suffice. The emulsion obtained is collected and added to pre- filter beer.

Large Scale

Acidified ethanol and hops are mixed in a vat of suitable size. The oils are then extracted using the beer itself by pumping the beer through the hops as a wash. For this, a vertical cylindrical tank may be used with a hinged top and base with suitable seals. This allows the hops to be tipped in directly from the mixer and then easily removed via the base afterwards.

A beer inlet and outlet valve are fitted centre top and centre base, the inlet at the base. A gas inlet is needed centre top and base. A mesh baffle is fitted to the hinged top and base to retain the hops within the tank.

The required quantity of hops are added from the mixer to the "hop oil extractor" and the hinged top is secured. A suitable purging gas is introduced from the base to purge out entrained air. The beer inlet and outlet are connected to the inlet and outlet of the conditioning tank and beer pumped in via the base to percolate through the hops and return to the conditioning tank.

This is carried out slowly to minimize disturbance of sedimented yeast. The longer the beer is recirculated, the more oils will be extracted.

After extraction, beer remaining in the extractor is gently blown back into the conditioning tank with a gas introduced via the gas inlet valves. Extraction is enhanced by occasionally introducing gas, such as nitrogen, into the base of the hop oil extractor, to agitate the contents.

The extraction of hops in this manner has considerable advantage over liquid carbon dioxide extraction. The hops are subjected to further esterification and any hop variety can be used. Also carbon dioxide extracts are very costly. Liquid carbon dioxide extracts can be used as the hop oil feedstock for the process if desired by diluting the extract with ethanol acidified to pH4 with phosphoric acid and then adding the emulsion to the conditioning beer.

Addition of Ethene

Three main options exist for the timing of ethene additio .

(a) Addition of ethene to the beer in the pre-filter conditioning tank

Success is dependent on the absence of oxygen or oxidised material in the beer.

Pure water is saturated with an ethene/carbon dioxide mix by using a suitable gas diffuser. A suitable gas mix is 75% carbon dioxide, 25% ethene. The gas is trickled into the water via the suction side of a centrifugal pump set up to recirculate the water being treated, the pump also acting as a gas diffuser. The gases may be metered into the water using a gas flowmeter and a timer, to give a desired mixed gas/water ratio. The hop wash is then added to the gas/water mix with the recirculating pump or high speed stirrer running to ensure adequate mixing of the resultant emulsion. About 45 litres of ethene may be added per kilogram of hops used, according to the hop oil content of the emulsion. After mixing, the emulsion is allowed to cool. The emulsion, or a desired quantity of it is then injected into chilled beer entering at the base of the recipient tank using a high speed pump, to give an equivalent in emulsion of about 80g of hops per 100 litres final beer volume. The beer is held at the pre-filtration stage. The beer is filtered off when it is of sufficient clarity. This is normally in three or four days.

If the beer is to be subject to a redox treatment, the ethene and hop oils should be added not less than four days before, and in no circumstances, after redox. Redox treatment of beer may inhibit transesterification of hop oil esters by ethene.

(b) Addition of ethene at carbonation

The ethene can be added with the carbon dioxide at carbonation. This method avoids any possible disturbance of settled sedimented yeast by addition during the pre-filter stage. In this method, 2000 litres of filtered beer which has had an emulsion of extracted hop oils from 2 kilograms of hops added to it during the pre-filter conditioning stage, would require 90 litres of ethene to be added. If the beer is required to contain 4 volumes of carbon dioxide, a gas mix of 90 litres of ethene plus 8000 litres of carbon dioxide is required. This is an ethene/carbon dioxide mix of 1.1% ethene to 98.9% carbon dioxide (vol/vol). Normal carbonation is undertaken with this gas mix.

(c) Direct addition of ethene to beer

As an alternative, a continuous feed of ethene gas can be added to recirculating beer itself to give the beer the same ethene content as in examples (a) and (b) , that is, about 45 litres of ethene for the emulsion prepared from 1 kilogram of hops.

As ethene does not have to be added to water, this method is useful if addition of dilution water is not required. Using a suitable diffuser to get the gas into solution, pure ethene can be used or an ethene/carbon dioxide mix.

After the carbonation stage, air incorporation during bottling should be avoided. Carbonated beer may be given redox treatment not less than four days after ethene addition and prior to bottling. Bottles must be tinted to prevent penetration of ultra-violet or near ultra-violet light. Such light may cause residual hop chlorophyll in the beer to produce further ethene causing the beer to develop a gas-burnt aroma and taste.

The methods shown in these examples provide commercial advantages for brewers by providing controllable methods of enhancing hop flavour in beer that reduce inefficiencies and inconsistencies of known methods. Also brewers are able to use hops of their choice rather than have to rely on extracts available. Cost may be reduced because traditional C0₂-prepared extracts are very costly. Other advantages include the fact that the head retention on beer is improved, and yeast which ferment at higher temperatures can be used. Loss of hop aromatics with such yeast is less of a problem using the process according to the invention. Example 2

Application of Ethene to Yeast

A gas mix of 75% C0₂ and 25% ethene is used to diffuse into wort when injected into the hot end of a para-flow wort cooler. A suitable metering device and timer is used to determine when a desired amount of gas mix has been absorbed into the wort.

In particular, 2 litres of ethene/1,000 litres ex copper wort at a specific gravity of 1.080 is used. This means at a 75/25 carbon dioxide/ethene gas mix, 8 litres gas mix is absorbed, 2 litres of which is ethene. A pitching rate of 2 litres wet yeast is used. Effectively, 2 litres ethene per 2 litres wet yeast is used for an all malt wort. If a catabolite repressing sugar is used as a wort adjunct ethene levels may need to increased.

It is understood that the invention is not limited to the described embodiments but that numerous variations and modifications may be made to these embodiments without departing from the scope of the invention as set out in the claims.

Moreover, where specific processing steps, materials and apparatus have been described, and known equivalents exist thereto, such equivalents are incorporated as if specifically set forth.

Industrial Applicability

The method of the invention may find wide application in the enhancement of flavours in food products, particularly fermented products, and more particularly beer.

Claims

1. A method of adding flavour to food products comprising combining ethene with a food product other than by way of contacting the ethene to a food product and holding the food product in a gaseous atmosphere at normal atmospheric pressure.

2. A method of adding flavour to food products comprising combining ethene in a mixture with a solid, liquid or gas or combination thereof with the food product.

3. A method according to claim 1 or claim 2 wherein the food product is beer.

4. A method according to claim 3 wherein the ethene is combined with essential oils from hops prior to its combination with beer.

5. A method according to anyone of claims 1 to 4 wherein the ethene is combined with carbon dioxide prior to its contact with any other substance.

6. A method according to claim 5 wherein the carbon dioxide is present in a higher ratio (vol/vol) than the ethene.

7. A method according to claim 6 wherein the ratio of ethene to carbon dioxide is 25:75 (vol/vol).

8. A method according to any one of claims 1 to 7 wherein the ethene or ethene/carbon dioxide mix is combined with water and wherein the ethene/water or ethene/carbon dioxide/water mix is added to the food product.

9. A method according to claim 8 wherein the ratio of water to ethene or water to ethene plus carbon dioxide is 1:12 (vol/vol).

10. A method of adding flavour to a food product comprising combining ethene with a flavouring substance and adding the resulting combination to the food product.

11. A method according to claim 10 wherein the flavouring substance is essential oils from hops and the food product is beer.

12. A method according to claim 10 or claim 11 wherein the ethene is combined with carbon dioxide prior to combination with the flavouring substance.

13. A method according to claim 12 wherein the carbon dioxide is present in a higher ratio (vol/vol) than the ethene.

14. A method according to claim 13 wherein the ratio of ethene to carbon dioxide is 25:75 (vol/vol).

15. A method according to any one of claims 10 to 14 wherein the ethene or ethene/carbon dioxide mix is combined with water prior to combining it with the flavouring substance.

16. A method according to any one of the preceding claims wherein the ethene or ethene mix is added to beer in a pre-conditioning tank.

17. A method according to claim 5 or claim 12 wherein the ethene/carbon dioxide mix is added to the beer at the carbonation stage of beer production.

18. A method according to claim 17 wherein the ratio of ethene to carbon dioxide is 1.1% to 98.9% (vol/ vol) .

19. A method according to claim 4 or claim 11 wherein the essential oils from hops are obtained by washing hops with acidified alcohol followed by stripping of essential oils from the hops with demineralised, acidified water.

20. A method of improving the flavour in a fermentable food product comprising mixing ethene into a substrate suitable for contact with yeast during fermentation.

21. A method according to claim 20 wherein the ethene is combined with carbon dioxide.

22. A method according to claim 21 wherein the ratio of ethene to carbon dioxide is 25:75 (vol/vol).

23. A method according to any one of claims 20 to 22 wherein the ethene is diffused into wort during fermentation of beer.

24. A method according to claim 23 wherein the volume of ethene used equals the volume of yeast.

25. A method of enhancing flavour in dairy products comprising adding ethene to the dairy product.

26. A method of adding flavour to a food product, substantially as herein described with reference to Example 1.

27. A method of improving the flavour in a fermentable food product substantially as herein described with reference to Example 2.

28. A food product when prepared according to the method of any one of claims 1 to 27.

29. A flavouring composition for use in enhancing flavour in a food product comprising ethene together with water and/or carbon dioxide.

30. A flavouring composition comprising ethene together with a flavouring substance.

31. A flavouring composition according to claim 30 wherein the flavouring substance is hops or hop extract including essential oils from hops.

32. A flavouring composition according to claim 30 or claim 31 wherein the ethene is combined with water and/or carbon dioxide prior to combination with a flavouring substance.