METHOD OF IMPROVING FROTH ON BEVERAGE DISPENSED FROM A CONTAINER

Abstract: A method of improving the foaming characteristics of a nitrogenated liquid product such as beer, that is packaged in cans or bottles or other suitable containers is disclosed. The method inlcudes the steps of shaking a sealed container to disperse bubbles of nitrogen throughout the liquid product and immediately thereafter opening the container and pouring the liquid product from the container. A method of producing a liquid product, such as beer packed in cans or bottles or other suitable containers is also disclosed. The method is characterised by injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product prior to, during or after filling the liquid product into cans or bottles or other suitable containers.

Description: METHOD OF IMPROVING FROTH ON BEVERAGE DISPENSED FROM A CONTAINER The present invention relates to a liquid product in cans or bottles or any other suitable containers. The present invention relates particularly to a liquid product, such as beer, which contains nitrogen for the purpose of causing the liquid product to have a smooth, non-bitter, taste and excellent foaming characteristics. The present invention also relates to a method of producing a liquid product packed in cans or bottles or any other suitable containers . In this context, the present invention relates particularly, although by no means exclusively, to a method of producing a carbonated beverage product, such as beer, packed in cans or bottles or any other suitable containers, which method is characterised by injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the containers . One particular, although by no means exclusive, application of the present invention is beer and the following discussion of the prior art is in this context. Australian patent application 55602/86 entitled "Carbonating in Bottles and Cans" in the name of Gatehouse Technical Ventures Limited describes that foam is an important element in the consumer appeal of most beers and of some other carbonated beverages. More particularly, the Gatehouse patent application describes that: "The most important means by which foam is produced by any of these liquids is the release of carbon dioxide from super-saturated solution. Super-saturation arises when a previously-closed, pressurised container is opened to atmosphere or when the liquid contents are discharged from within it through a tap or similar device. Bubbles of carbon dioxide gas are then released by turbulent flow, by nucleation on solid surfaces or particles, or by diffusion into existing gas bubbles. In the case of beers and other carbonated beverages, bubbles aggregate to produce foam which rests on top of the beverage in the drinking-glass (or other drinking container) . More bubbles are released, and foam consequently produced, as the beverage is drawn into and flows within the mouth, producing a variety of sensory impressions including viscosity. As the beverage is tipped from the glass, foam clings to its walls, giving an attractive pattern known as 'lacing'." It is known that carbonation causes beer to have carbon dioxide bite and, whilst this taste is regarded favourably by some sections of the consumer market, there are other sections of the market that regard the taste as undesirable. It is known to add nitrogen to beer as an alternative means of producing foam in beer. It is also known that nitrogen causes beer to have a smoother, less bitter, taste. It is also known to add nitrogen to cans to generate super-atmospheric pressure in the head-spaces of the cans to prevent deformation of the sealed cans during normal handling of the cans. There are a number of known options for introducing nitrogen into beer. One option is to dissolve nitrogen in beer prior to filling into cans or bottles. This option is described in a number of patent applications and patents including, by way of example, Australian patents 642219 and 642714 in the name of The BOC Group pic and International application PCT/SE95/01449 (WO 96/17529) in the name of Tetra Laval Holdings & Finance S A. In each of these patents and patent application, the main stated reason for adding nitrogen to cans is to generate super-atmospheric pressure in the head-spaces of the cans to prevent deformation of the sealed cans . The addition of nitrogen to non-carbonated liquid products prior to filling into cans or bottles is also described in a number of patents and patent applications including, by way of example, Australian patent 642789 in the name of The BOC Group pic, ϋ patent application 2134496 in the name of Asahi Breweries Ltd, and US patent 4347695 in the name of General Foods Corporation. The Gatehouse patent application describes the option of dissolving nitrogen in beer prior to filling into cans or bottles in the following negative terms: "if nitrogen is dissolved in the beverage in a reservoir before a filling operation carried out in currently used equipment for filling small containers with carbonated beverages, most of the nitrogen is removed by 'gas washing' because, due to the much lower solubility of nitrogen than carbon dioxide in the liquid, any bubbles liberated by liquid movement entrain nitrogen." Another option for introducing nitrogen into beer is to add nitrogen to beer at a filling station. The Gatehouse patent application describes as an invention a method of producing cans and bottles containing beer in accordance with this option which comprises the steps of: (i) partially filling a can or bottle with a predetermined quantity of beer; (ii) adding a predetermined quantity of liquid nitrogen to the container or bottle; and (iii) sealing the can or bottle. The Gatehouse patent application describes that the addition of nitrogen to beer in amounts of up to 1.14 grams of liquid nitrogen per litre of beer was found to progressively improve foaming properties of beer. International application PCT/AU98/00540 of the applicant proposes the addition of nitrous oxide and optionally nitrogen as an alternative means of producing beer that has good foaming characteristics and has a smoother, less bitter taste than beer that contains carbon dioxide only. The preferred method disclosed in the International application includes the step of pressurising beer after injecting nitrous oxide, carbon dioxide and nitrogen into the beer in order to improve the solubility of the injected nitrous oxide, carbon dioxide, and nitrogen in the beer. The disclosed preferred method also includes the subsequent step of depressurising the beer to a suitable filling pressure before filling the beer into cans, bottles or other suitable containers. Notwithstanding the disclosure in the Gatehouse patent application and in other patent applications and patents, as far as the applicant is aware, there is no commercially available canned or bottled, ie packaged, beer that contain nitrogen in accordance with the above options that has satisfactory foaming characteristics. In particular, the applicant is not aware of any commercially available canned or bottled beer that contain nitrogen in accordance with the above options that generates foam that "surges" after the beer is poured into a glass - which is a characteristic feature of nitrogenated beers that are available on tap. As a consequence of the inadequate foaming characteristics of canned or bottled beer that contain nitrogen in accordance with the above options, the brewing industry has developed a further option for introducing nitrogen into beer which is based on the use of inserts, commonly referred to as "widgets", positioned in cans or bottles. The widgets store nitrogen gas when the cans are sealed and release the gas as small bubbles when the cans or bottles are subsequently opened. There has been considerable research and development work into widgets. As a general proposition it can be said that widgets improve the foaming characteristics of nitrogenated beer. This is reflected in that, as far as the applicant is aware, commercially available canned nitrogenated beer is only available in cans or bottles having widgets. The extent of research and development work and the importance of widgets is also reflected by the number of patent families for widgets in Australia and elsewhere. Notwithstanding the improved foaming characteristics that are attributable to widgets, there is a cost penalty associated with the use of widgets, and in the circumstances there is a need for a non-widget solution to the problem of generating foam in nitrogenated beer (and other liquid products) . One objective of the present invention is to provide a method of improving the foaming characteristics of canned or bottled, ie packaged, nitrogenated beer. Another objective of the present invention is to provide an improved method of producing cans or bottles or other suitable containers containing beer. A particular objective is to provide a method which is an improvement over that described in International application PCT/AU98/00540. According to a first aspect of the present invention there is provided a method of improving the foaming characteristics of a nitrogenated liquid product that is packaged in cans or bottles or other suitable containers which includes the steps of shaking a sealed can or bottle or other suitable container to disperse bubbles of nitrogen throughout the liquid product and immediately thereafter opening the container and pouring the liquid product from the container. The applicant has now found surprisingly that shaking a sealed can or bottle or other container containing nitrogenated beer and thereafter opening the container and pouring the beer from the container significantly improves the foaming characteristics and, more particularly, the surge quality of the beer. The applicant has found that this surprising beneficial result caused by shaking the container applies to nitrogenised beer in containers : (i) with or without widgets; and (ii) with or without other foaming additives, such as nitrous oxide and carbon dioxide. The result is surprising because it is usually the case that deliberate shaking of cans or bottles of beer should be avoided because, usually, canned/bottled beer is highly carbonated and shaking has the adverse effect of producing uncontrolled spray when the cans or bottles are opened. The applicant believes that the effect of shaking is to create small bubbles of nitrogen and to disperse these throughout the beer, whereby after cans or bottles of such beer are opened and poured immediately into a glass, the small bubbles generate a surge effect. The term "immediately thereafter" is understood to mean that the beer is poured within 2 minutes of opening the container. The extent of shaking may vary considerably depending on factors such as the amount of nitrogen in the beer and the amount of other foaming agents, such as carbon dioxide and nitrous oxide, in the beer. Typically, cans or bottles or other suitable containers are held and are given one or more short, sharp to and fro movements in the axial direction of the containers which shake the contents of the containers . The nitrogenated beer may be produced by any suitable method. The nitrogenated beer may include any suitable amount of nitrogen. The nitrogenated beer may also include one or more than one other foaming additive, such as nitrous oxide or carbon dioxide. According to a second aspect of the present invention there is provided a method of producing a liquid product packed in cans or bottles or other suitable containers which includes the steps of filling the liquid product into cans or bottles or other suitable containers and sealing the cans or bottles or other suitable containers, and which method is characterised by injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product prior to, during, or after filling the liquid product into cans or bottles or other suitable containers and without externally pressurising the liquid product after injecting the nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide. The term "externally pressurising" is understood to mean applying pressure to a liquid product by external means and not as a result of pressure generated by the injection of nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide. With reference to international application PCT/AU98/00540, this aspect of the present invention is based on the unexpected realisation that it is not necessary to externally pressurise a liquid product after nitrous oxide and, optionally, one or more than nitrogen and carbon dioxide has been injected into the liquid product . The second aspect of the present invention extends to situations in which nitrous oxide (with or without other additives) is injected at any one of the stages, namely prior to, during, and after filling containers and to situations in which nitrous oxide (with or without additives) is injected and two or more of these stages . The nitrous oxide, nitrogen and carbon dioxide may be in a gaseous or a liquid state. Preferably the method includes: (i) injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product; (ii) without externally pressurising the liquid product after step (i), filling the liquid product into cans or bottles or other suitable containers; and (iii) thereafter sealing the cans or bottles or other suitable containers . The cans or bottles or other suitable containers may be made from any suitable material. By way of example, suitable materials include, metal, glass and plastics. Preferably the method further includes injecting nitrogen into the cans or bottles or other suitable containers prior to, during, or after filling the cans or bottles or other suitable containers. In this context the present invention extends to situations in which nitrogen is injected in each stage, ie prior to, during, and after filling the cans or bottles or other containers. More preferably the method further includes injecting nitrogen into the cans or bottles or other suitable containers after filling the cans or bottles or other suitable containers with liquid product and before sealing the cans or bottles or other suitable containers. In one embodiment the method includes chilling the liquid product to a predetermined temperature prior to injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product. In another embodiment the method includes chilling the liquid product to a predetermined temperature after injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product . Preferably the predetermined temperature is in the range of -1°C-8°C. More preferably the temperature range is -1°C- 4°C. It is preferred particularly that the temperature range be -1°C-1°C. Nitrous oxide may be the only additive. Optionally, the method includes injecting any suitable combination of nitrous oxide and one or more than one of nitrogen and carbon dioxide. Specifically: nitrous oxide and nitrogen; nitrous oxide and carbon dioxide; and nitrous oxide, nitrogen and carbon dioxide may be injected into the liquid product. In a situation where the liquid product is beer, carbon dioxide injection may not be necessary because the beer has sufficient carbonation. In a situation where the liquid product is beer, it is preferred that some nitrogen be injected prior to filling the cans or bottles or other suitable containers and that further nitrogen or the balance of nitrogen required be injected into the containers prior to sealing the containers . Preferably, the nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide are injected as a gas. The nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide may be injected into the liquid product as a gas mixture or as separate gases or as a liquid mixture or as separate liquids or as mixtures of gases and liquids . Preferably, the liquid product supplied to the process a carbonated liquid product. The method may include stripping excess carbon dioxide from the liquid product prior to injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide. In a situation where the liquid product is beer, the principal purpose of nitrous oxide is to take away the adverse effect of carbon dioxide bite caused by carbon dioxide. Nitrous oxide also enhances the head of a beer poured into a glass. The nitrogen is added principally to generate small bubbles which produce foam when sealed cans or bottles are opened. The carbon dioxide and nitrous oxide are more soluble than nitrogen and therefore are not as effective as nitrogen in generating foam - although a portion of both gases will contribute to producing foam when the cans or bottles are opened. The principal purpose of adding carbon dioxide to beer is to ensure that beer does not go "flat" shortly after being poured from the can or bottle into a glass or other container. In addition to the above, each of nitrogen, carbon dioxide and nitrous oxide contributes to producing a super atmospheric pressure in the head spaces of sealed cans or bottles or other suitable containers to withstand deformation during normal handling of the sealed cans or bottles or other suitable containers. According to the present invention there is also provided a liquid product contained under pressure in a sealed can or bottle or other suitable container, which liquid product includes nitrous oxides, nitrogen, and carbon dioxide, which are released as gaseous phases and cause foaming of the liquid product when the can or bottle or other suitable container is opened. Preferably the sealed can or bottle or other suitable container contains 0.01-4 volumes of nitrous oxide per unit volume of the liquid product. More particularly the sealed can or bottle or other suitable container contains 0.01-1.2 volumes of nitrous oxide per unit volume of the liquid product. More preferably the sealed can or bottle or other suitable container contains 0.01-0.8 volumes of nitrous oxide per unit volume of the liquid product. Preferably the sealed can or bottle or other suitable container contains 0.1-3.5 volumes of carbon dioxide per unit volume of the liquid product. More preferably the sealed can or bottle or other suitable container contains 0.5-2.6 volumes of carbon dioxide per unit volume of the liquid product. More preferably the sealed can or bottle or other suitable container contains 0.9-1.7 volumes of carbon dioxide per unit volume of liquid product. It is preferred particularly that the sealed can or bottle or other suitable container contains 1.2-1.6 volumes of carbon dioxide per unit volume of liquid product . Preferably the sealed can or bottle or other suitable container contains 0.1-2.8 volumes of nitrogen per unit volume of the liquid product. More particularly the sealed can or bottle or other suitable container contains 0.5-1.2 volumes of nitrogen per unit volume of the liquid product. More preferably the sealed can or bottle or other suitable container contains 0.8-1.2 volumes of nitrogen per unit volume of the liquid product. It is preferred particularly that the sealed can or bottle or other suitable container contains 1-1.2 volumes of nitrogen per unit volume of the liquid product. Preferably the internal pressure of the sealed bottle or container is greater than 3 atmosphere absolute at ambient temperature. More preferably the internal pressure is 4-5 atmospheres absolute. Preferably the sealed can or bottle or other suitable container does not include a "widget" or other device for storing nitrogen, carbon dioxide and nitrous oxide for release when the can or bottle is opened. Preferably the liquid product is beer. The applicant has carried out a series of experiments/trials producing and thereafter testing liquid products in sealed cans. The applicant found that canned products, such as beer, produced in accordance with the method of the second aspect of the present invention, exhibited excellent foaming characteristics and taste. The applicant also found in the series of experiments/trials that the foaming characteristics of the packaged beer were enhanced in accordance with the first aspect of the present invention by shaking the cans prior to opening the cans and pouring out the liquid products. As is indicated above, this is a surprising result in relation to carbonated liquid products because usually it is the case that even minor amounts of shaking generate excessive amounts of foaming and are undesirable for this reason. The following discussion highlights the key results of the experiments/trials for this aspect of the present invention. Definitions: 1. Surge - a cascade or ripple effect produced by effervescence or dispersed gas bubbles in the beverage (particularly beer) as the bubbles rise to the top of the beer. This phenomenon can be observed where beer is dispensed from a tap into a conical beer glass. 2. Surge time - duration of the surge measured from the time the beer glass is fully filled to the time the surge disappears, ie when the boundary between the head and the beer is distinct or clear cut . 3. Head size - the height of the foam above the beer in a glass . 4. Serving temperature - the temperature of beer measured after it is filled into a beer glass. 5. Head-space - the empty space above the liquid content in a container. 6. Gas volume - total volume of a gas dissolved in the beer or present in the head-space per volume of beer in the container. 7. Shake - a complete to and fro swing of a beer container. A light shake is one where the distance traversed by the container is less than 200mm. A heavy shake is one where the distance traversed is more than 250mm. In the experiments/trials, the applicant found that, for a given gas mixture and composition, a given level of foaming agents (eg hop extract and PGA used in the brewing industry) , and a given serving temperature, the number of light shakes given to the packaged beer affects the surge time and the head size. Typical examples are: 1. Type of beer: bitter, draught Gas composition: 1.2 v/v C0 2 , 0.03 v/v N 2 0, 0.8 v/v N 2 Serving temperature:4°C Surging times: 20 seconds after 1 light shake; 30 seconds after 2 light shakes; 50 seconds after 3 or more light shakes Head sizes: 15mm after 1 light shake; 18mm after 2 light shakes; 25mm after 3 or more light shakes . Type of beer: stout, draught Gas composition: 1.2 v/v C0 2 , 0.03 v/v N 2 0, 0.9 v/v N 2 Serving temperature: 4°C Surging times : 35 seconds after 1 light shake; 55 seconds after 2 light shakes; 90 seconds after 3 or more light shakes Head sizes: 18mm after 1 light shake; 20mm after 2 light shakes; 23mm after 3 or more light shakes . Type of beer: lager, draught Gas composition: 1.4 v/v C0 2 , 0.03 v/v N 2 0, 0.8 v/v N 2 Serving temperature :4°C Surging times: 20 seconds after 1 light shake; 30 seconds after 2 light shakes; 45 seconds after 3 or more light shakes Head sizes: 20mm after 1 light shake; 22mm after 2 light shakes; 25mm after 3 or more light shakes . One heavy shake approximates 2 light shakes; 2 heavy shakes approximate 3 or more light shakes. Shaking the container before opening imparts two things to the beer: 1. Gases in the head-space are dissolved or dispersed into the beer; and 2. A foamy head is formed in the container. The foamy head and the extra gases dissolved or dispersed in the beer help to produce the surge when the container is subsequently opened and the beer poured into a conical glass . Similar patterns in surge time and head size can be obtained with beer containing C0 2 and N 2 , with or without N 2 0. The second aspect of the present invention is described further by way of example with reference to the accompanying drawing which is one preferred embodiment of a method of producing canned beer in accordance with the present invention. The preferred embodiment described below relates to producing beer. It is emphasised that the present invention is not limited to producing beer and extends to producing any carbonated and non-carbonated liquid product. With reference to the figure, carbonated beer produced by conventional beer-making technology flows along a line 12 and excess carbon dioxide (if any) is stripped from the beer prior to the beer reaching a holding tank 14. The beer flows from the holding tank 14 through a chiller 16 in which the beer is chilled to a temperature in a range of -1°C to 4°C. Thereafter, the beer flows to a filling station 26 at which the beer is filled into cans and the filled cans are sealed. Nitrous oxide in gaseous form is injected into the beer upstream of the chiller 16. The gas may be injected on its own or as a gas mixture with one or more than one of carbon dioxide and nitrogen. In a situation where carbon dioxide and nitrogen are injected into the beer, each gas may be injected on its own or as a gas mixture with the other gases . The amount of each gas injected into the beer should be within the broad ranges described above and having regard to the levels of injection of the other gases. As a general guideline, as the level of injected carbon dioxide increases, the level of injected nitrous oxide can decrease. In addition to the gas injection prior to the chiller 16, liquid nitrogen is injected into the head space of each filled can prior to sealing the can. The injection of liquid nitrogen at this point rather than upstream of the filling station 26 is preferable in view of the comparatively low solubility of nitrogen in beer. Moreover, injection of liquid nitrogen at this point obviates the capital and operating costs associated with pressurising beer to improve the solubility of nitrogen in the beer and thereafter depressurising the beer to a suitable filling pressure as is required in the International application of the applicant that is discussed above. Many modifications may be made to the preferred embodiments described above without departing from the spirit and scope of the present invention. By way of example, whilst the preferred embodiment described above chills the beer after injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the beer, the present invention is not limited to this arrangement and gas injection can be made after chilling the beer.

Claims: CLAIMS : 1. A method of improving the foaming characteristics of a nitrogenated liquid product that is packaged in cans or bottles or other suitable containers which includes the steps of shaking a sealed can or bottle or other suitable container to disperse bubbles of nitrogen throughout the liquid product and immediately thereafter opening the container and pouring the liquid product from the container. 2. The method defined in claim 1 includes holding the sealed container and giving one or more short, sharp to and fro movements in the axial direction of the container which shake the contents of the container. 3. The method defined in claim 1 or claim 2 wherein the liquid product is beer and the beer includes one or more than one other foaming additive, such as nitrous oxide or carbon dioxide. 4. A method of producing a liquid product packed in cans or bottles or other suitable containers which includes the steps of filling the liquid product into cans or bottles or other suitable containers and sealing the cans or bottles or other suitable containers, and which method is characterised by injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product prior to, during or after filling the liquid product into cans or bottles or other suitable containers and without externally pressurising the liquid product after injecting the nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide. The method defined in claim 4 includes: (i) injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product; (ii) without externally pressurising the liquid product after step (i), filling the liquid product into cans or bottles or other suitable containers; and (iii) thereafter sealing the cans or bottles or other suitable containers . 6. The method defined in claim 4 or claim 5 further includes injecting nitrogen into the cans or bottles or other suitable containers prior to, during or after filling the cans or bottles or other suitable containers . 7. The method defined in any one of claims 4 to 6 further includes injecting nitrogen into the cans or bottles or other suitable containers after filling the cans or bottles or other suitable containers with liquid product and before sealing the cans or bottles or other suitable containers. 8. The method defined in any one of claims 4 to 7 includes chilling the liquid product to a predetermined temperature prior to injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product. . The method defined in any one of claims 4 to 7 includes chilling the liquid product to a predetermined temperature after injecting nitrous oxide and, optionally, one or more than one of nitrogen and carbon dioxide into the liquid product . 10. The method defined in claim 8 or claim 9 wherein the predetermined temperature is in the range of - 1°C-8°C. 11. The method defined in any one of claims 4 to 101 wherein when the liquid product is beer, the method includes injecting some nitrogen prior to filling the cans or bottles or other suitable containers and injecting further nitrogen into the containers prior to sealing the containers .

Inventors: PAN CHRISTOPHER CHIA SHYONG, PAN, CHRISTOPHER, CHIA, SHYONG
Applicants: AMCOR PACKAGING AU PTY LTD, PAN CHRISTOPHER CHIA SHYONG, AMCOR PACKAGING (AUSTRALIA) PTY LTD, PAN, CHRISTOPHER, CHIA, SHYONG
Application year: 1999
Main classification: B65D85
IPC codes: A23L2, B65D81, C12C11