Patent Publication Number: US-9427105-B2

Title: Beverage preparation machines

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 13/318,044, filed Oct. 28, 2011, which is a U.S. national phase application of International Appl. No. PCT/GB2010/000551, filed Mar. 24, 2010, which claims benefit from Great Britain Appl. No. 0907612.6, filed May 1, 2009, and which are hereby incorporated by reference in their entirety. 
    
    
     FIELD 
     The present invention relates to improvements in beverage preparation machines and in particular to a beverage preparation machine of the type which uses pre-packaged containers of beverage ingredients. 
     BACKGROUND 
     Coffee houses have been a part of the “coffee culture” since the 17 th  century. Throughout the years methods of making coffee have been refined and skilled people trained to produce the best coffee beverages. The first coffee machines were developed in the early 1800s and an automatic espresso machine was invented in the 1930s. The automation of the coffee making process has, in turn, lead to a rapid growth, particularly in the last ten years, in the number of coffee houses/shops with more specialist drinks, such as espresso and cappuccino, being in high demand. These types of beverages have historically been regarded as luxury items because of the need for expensive, complex machines capable of producing the high pressures necessary for making them, which had to be properly operated and maintained by a trained barista to produce good quality. Coffee aficionados agree that an espresso can be spoiled by a badly trained operator despite the use of a good quality machine and good quality coffee. This trend, however, has not only lead to an increased demand from consumers for luxury top quality beverages, but also a desire for a greater variety of speciality beverages, and the ability to make such beverages in the comfort of one&#39;s own home. 
     Although there is no agreed technical definition, it is generally understood that, compared to drip coffee, barista quality espresso has a thicker consistency, due to a higher amount of dissolved solids and fine oil droplets suspended throughout the drink. It has a smooth, yet thick, dark reddish brown crema making up 10 to 30% of the beverage. The crema is a polyphasic emulsion of air and the oils, proteins and sugars extracted from the coffee which is produced at a high pressure, traditionally in the region of 9 to 10 bar. The higher pressures increase the rate of coffee wetting and improve extraction as well as being responsible for the development of the crema. 
     It is acknowledged, by discerning espresso drinkers, that espresso produced using water which is cooler than the optimum temperature tastes sour and that produced with water which is hotter than this temperature tastes bitter. The optimum temperature is claimed to be between 92 and 96° C. Other factors which affect the quality of the espresso include the roasting and age of the coffee beans, the grind size, the compaction of the grinds prior to brewing, and the brew time. The “best” espresso is achieved by balancing these key elements of the brewing process. 
     Domestic coffee machines have also developed significantly since the first filter machines were invented in the 1960s and coffee machines are now essential pieces of kitchen equipment in many households. Some such machines dispense individual servings of a beverage directly into a drinking receptacle, and derive the beverage from a bulk supply of beverage ingredients or from individual packages of beverage ingredients such as pods, pads or cartridges. In the following specification such packages will be referenced by the general term cartridges. Machines which use such cartridges eliminate the need for cleaning and can enable the user to make a selection of beverages. An example of one type of such cartridge is described in EP-A-1440903. The beverages are formed from brewing, mixing, dissolving or suspending the beverage ingredients in water. For example, for coffee beverages, heated water is forced through the cartridges to form the extracted solution. The use of cartridges in such machines has become increasingly popular due to their convenience and the quality of the beverage produced. 
     An example of a machine for preparing beverages using this type of cartridge is described in EP-A-1440644. This type of machine provided, inter alia, an improvement over the prior art known at the time in that it operated at a lower pressure than the previously known machines, which were designed for the commercial or industrial markets rather than the domestic market. Hence it was more suitable for the domestic market in terms of cost, reliability and performance. However, the problem that faces systems that operate at a lower pressure is that they are generally not capable of producing barista quality espressos, which require a significantly higher pressure. 
     With the change in consumer trends, however, there is a desire for domestic machines which are capable of producing barista quality espresso and a range of other beverages, for which no training is necessary, which are affordable and which require little or no cleaning. 
     Some machines available on the market claim to produce higher quality beverages but for various reasons, they are comparatively expensive machines. Examples of such machines are the Gaggia L&#39;Amante™, the Gaggia Evolution™, the Nespresso Delonghi Latissimma 660 ™, and the Krups XN2101™. 
     Most of these machines require specially designed cartridges of increased complexity and a particular specification of materials to cope with the high pressures involved in the brewing process for espresso. These cartridges generally incorporate filters and the process uses the geometry of the cartridge to enable the desired quality of the beverage to be produced under high pressure. This constrains the use of the cartridges in the machine for which it is designed. 
     SUMMARY 
     It is, however, desirous to provide an improved beverage preparation machine capable of making a selection of beverages, including a premium quality espresso as well as non-espresso beverages, preferably using pre-packed beverage cartridges. The machine may also be a bulk brewer or other non-cartridge machine. 
     It is also desirous to provide a machine which is backwardly compatible with existing cartridges, such as those described in EP-A-1440903, which are used in existing low pressure beverage preparation machines. 
     Accordingly, the present invention provides a method of preparing beverages using a beverage preparation machine for preparing beverages from one or more beverage ingredients, characterised by controlling the volume of gas in at least a part of a delivery system of the machine to produce predetermined characteristics in a prepared beverage. 
     The volume of gas is preferably actively controlled by increasing the volume to increase the gas:liquid ratio in the beverage produced, decreasing the volume to decrease the gas:liquid ratio or maintaining the volume. 
     Preferably the volume of gas in the delivery system is controlled by inducting additional gas into the delivery system, venting gas from the delivery system and/or purging the delivery system. 
     The method preferably further comprises the step of measuring the actual volume of gas resident in the delivery system. 
     An actual volume of gas resident in the delivery system may be calculated from stored parameters relating to a volume of gas remaining in the delivery system after a last operation of the machine. 
     Control of the volume of gas is preferably effected on a beverage by beverage basis and is preferably effected automatically according to the type of beverage being produced. 
     Alternatively the control of the volume of gas is effected manually. 
     The volume of gas upstream and/or downstream of the beverage ingredients may be controlled. 
     Preferably the volume of gas is controlled by selectively opening and/or closing valve means in the delivery system prior to and/or during beverage preparation. 
     The invention also provides a beverage preparation machine for preparing a beverage from one or more beverage ingredients, characterised by the provision of means for controlling the volume of gas in at least a part of a delivery system of the machine to produce predetermined characteristics in a prepared beverage. 
     The machine preferably comprises means for determining the actual volume of gas resident in the delivery system. 
     The means for determining the actual volume of gas resident in the delivery system may comprise means for calculating the actual volume from stored parameters relating to a volume of gas remaining in the delivery system after a last operation of the machine. 
     Preferably the stored parameters comprise a basic volume parameter stored in the control means, said basic volume being the actual volume of gas which resides in the delivery system of an unused machine or a machine after a purging cycle has been run. 
     The stored parameters may comprise parameters relating to the actual volume of gas remaining in the delivery system after each type of beverage which the machine is programmed to prepare. 
     The means for determining the actual volume of gas resident in the delivery system preferably comprise means for measuring the actual volume of gas in the delivery system. 
     Parameters relating to predetermined volumes of gas required to be present in the delivery system for preparing a predetermined range of beverages are preferably stored in the control means, said control means being programmed to calculate the difference between the predetermined volume required for a beverage in preparation and the actual volume present. 
     The means for controlling the actual volume of gas may comprise valve and/or purge means for venting gas and/or pump means for injecting additional gas into the delivery system. 
     Preferably the valve means comprise an outlet valve downstream and/or a valve upstream of the beverage ingredients. 
     Operation of the valve means is preferably controlled relative to the beverage preparation cycle to vary the actual volume of gas present in the delivery system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  is a front perspective view of a prior art beverage preparation machine with the cartridge head in a closed position; 
         FIG. 2  is a front perspective view of the machine of  FIG. 1  with the cartridge head in an open position; 
         FIG. 3  is a rear elevation of the machine of  FIG. 1  with some parts omitted for clarity; 
         FIG. 4  is a front perspective view of a cartridge head of the machine of  FIG. 1  with some parts omitted for clarity; 
         FIG. 5  is another front perspective view of the cartridge head of  FIG. 4 , with some parts omitted for clarity; 
         FIG. 6  is a cross-sectional view of the cartridge head of  FIG. 4  in a closed position accommodating a version of a beverage cartridge; 
         FIG. 7  is a cross-sectional side elevation of the cartridge head of  FIG. 4  in an open position accommodating the beverage cartridge; 
         FIG. 7 a    is a plan view of a rubber seal for the cartridge head of  FIG. 4 ; 
         FIG. 8  is a schematic showing the various component parts of the machine of  FIG. 1  incorporating a new variable outlet valve; 
         FIG. 9  is a section of schematic of an outflow from the cartridge head incorporating the variable outlet valve of  FIG. 8 ; 
         FIGS. 10-12  are cross-sectional front elevations of one embodiment of the variable valve in the outflow of  FIG. 9  showing it&#39;s closed, open and restricted positions respectively; 
         FIGS. 13 a  and 13 b    are cross-sectional end elevations of an alternative variable outlet valve used in the outflow of  FIG. 9  in its open and closed position respectively; 
         FIGS. 14 and 15  are cross-sectional side elevations of the valve of  FIGS. 13 a    and  13   b;    
         FIG. 16 a    is a side elevation of a beverage receptacle containing a coffee beverage having a large volume of crema produced using an improved gas management system; 
         FIG. 16 b    is a chart showing the brew parameters used in producing the beverage illustrated in  FIG. 16   a;    
         FIG. 17 a    is a side elevation of a beverage receptacle containing a coffee beverage having a small volume of crema produced using the improved gas management system; 
         FIG. 17 b    is a chart showing the brew parameters used in producing the beverage illustrated in  FIG. 17   a;    
         FIG. 18  is a plan view of a beverage cartridge suitable for use in the beverage preparation machine of  FIG. 1 ; 
         FIG. 19  is cross-sectional side elevation of an outer member of the cartridge of  FIG. 18 ; 
         FIG. 20  is a cross-sectional side elevation of a detail of the outer member of  FIG. 19  showing an inwardly directed cylindrical extension; 
         FIG. 21  is a cross-sectional side elevation of a detail of the outer member of  FIG. 19  showing a slot; 
         FIG. 22  is a perspective view from above of the outer member of  FIG. 19 ; 
         FIG. 23  is a perspective view from above of the outer member of  FIG. 19  in an inverted orientation; 
         FIG. 24  is a plan view from above of the outer member of  FIG. 19 ; 
         FIG. 25  is a cross-sectional drawing of an inner member of the cartridge; 
         FIG. 25 a    is a cross-sectional drawing of a detail of the inner member of  FIG. 25  showing an aperture; 
         FIG. 26  is a perspective view from above of the inner member of  FIG. 25 ; 
         FIG. 27  is a perspective view from above of the inner member of  FIG. 25  in an inverted orientation; 
         FIG. 28  is another cross-sectional drawing of the inner member of  FIG. 25 ; 
         FIG. 28 a    is a cross-sectional drawing of another detail of the inner member of  FIG. 25  showing an air inlet; 
         FIG. 29  is a cross-sectional side elevation of the cartridge in an assembled condition; and 
         FIG. 30  is a cross-sectional side elevation of another version of cartridge. 
     
    
    
     DETAILED DESCRIPTION 
     In order to cater for the desired wide selection of good quality beverage types, having different characteristics, the present invention involves one or more significant improvements to known beverage preparation machines. These improvements enable sufficiently high pressures to be generated and maintained for the production of good quality espressos, and the pressure to be varied in a manner which is invisible to the user and requires no manual intervention. Furthermore they enable the crema to be improved in a way not previously possible. 
     These improvements, which will be described in more detail below, include:— 
     1. providing a variable geometry valve downstream of the beverage cartridge to enable the beverage preparation machine to operate at a range of pressures; and 
     2. providing greater control over the end appearance of the dispensed beverage, in particular beverages with crema, by controlling the volume of gas passed through the beverage ingredients. 
     The aforementioned improvements will be described with reference to a known beverage preparation machine  10  which is illustrated in  FIGS. 1 to 7  of the accompanying drawings. It should be noted, however, that the improvements find application in a wide range of beverage preparation machines capable of using a wide range of cartridges which, as noted above, include pods, pads, rigid and semi-rigid cartridges. 
     The beverage preparation machine  10  of  FIGS. 1 to 3  generally comprises a housing  11 , a tank  12 , a water heater  13 , a control processor (not shown), a user interface  16  and a cartridge head  17 . The cartridge head  17  in turn generally comprises a cartridge holder  18  for holding, in use, a beverage cartridge  100  and cartridge recognition means  20 . The cartridge head  17  further comprises inlet and outlet piercers  21 ,  22  for forming in the beverage cartridge  100 , in use, an inlet  107  for liquid to enter the cartridge  100  and an outlet  108  for the prepared beverage to exit the beverage cartridge  100 . 
     Although water is likely to be the most common liquid used in preparing beverages such as coffee, the machine  10  is also capable of handling other liquids, such as milk or milk preparations, for mixing with the beverage ingredients  200 . Any references herein to water should also be taken to include any form of liquid used in preparing beverages. 
     The housing  11  is preferably made in whole or in part from a suitable plastics material or metal. The housing  11  preferably comprises a clam-shell design having a front half  25  and a rear half  26  which allow access during assembly for fitting of the machine  10  components. 
     The front half  25  of the housing  11  defines a dispensing station  27  where dispensation of the beverage takes place, which includes a cupstand  23  with a drip tray located beneath. The machine user interface  16  is also located on the front of the housing  11  and comprises a plurality of control switches, for example, a start/stop button  28 , and a number of status indicators  29 - 32 . The status indicators  29 - 32  are preferably light emitting diodes (LED) which, for example, indicate readiness of the machine  10 , whether an error has occurred in the machine  10  operation, and the mode of operation of the machine  10 . The LEDs  29 - 32  may be controlled to illuminate at a constant intensity, to flash intermittently, or both depending on the status of the machine  10 . The LEDs  29 - 32  may have a variety of colours including green, red and yellow. The start/stop button  28  controls commencement of the dispense cycle and is preferably a manually operated push-button, switch or similar. 
     The tank  12  is located to the rear of the housing  11  and is preferably incorporated in, or connected to, the rear half  26  of the housing  11 . The tank  12  has an inlet for filling the tank  12  with water, or other liquid, which is closed off when the tank  12  is in position in the machine  10 . An outlet is provided towards a lower end of the tank  12  which communicates with the pump  14 . The tank  12  may be made from a transparent or translucent material to allow a consumer to view the quantity of water remaining in the tank  12 . Alternatively, the tank  12  may be made from an opaque material but have provided a viewing window therein. In addition, or in place of the above, the tank  12  may be provided with a low level sensor which prevents operation of the pump  14  and optionally triggers a warning indicator, such as an LED, when the liquid level in the tank descends to a preselected level. The tank  12  preferably has an internal capacity of approximately 1.5 liters. 
     The pump  14  is operatively connected between the tank  12  and the water heater  13 , as shown schematically in  FIG. 8 , and is controlled by the control processor. A suitable pump provides a flow rate of 900 ml/min of water at a pressure of 6 bar. The flow rate of water through the machine  10  can be controlled by the control processor to be a percentage of the maximum flow rate of the pump  14  by cycle chopping the electrical supply to the pump. Preferably the pump can be driven at any of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% of the maximum rated flow rate. The accuracy of the volume of water pumped is preferably + or −5% leading to a + or −5% accuracy in the final volume of the dispensed beverage. A volumetric flow sensor (not shown) is preferably provided in the flow line either upstream or downstream of the pump  14 . Preferably, the volumetric flow sensor is a rotary sensor. 
     The heater  13  is located in the interior of the housing  11 . One suitable heater  13  has a power rating of 1550 W and is able to heat water received from the water pump  14  from a starting temperature of approximately 20° C. to a nominal operating temperature of around 85° C. in under 1 minute. Preferably the dwell time between the end of one dispense cycle and the heater  13  being able to commence a subsequent dispense cycle is less than 10 seconds. The heater maintains the selected temperature to within + or −2° C. during the dispense cycle. The water for the dispense cycle is delivered to the cartridge head  17  at a predetermined temperature. The heater  13  is able to quickly adjust the delivery temperature to the required temperature, generally between 80° C. and 98° C. and possibly higher from the incoming water temperature. Where desired, the machine can incorporate a steam purge. The preferred means of generating the steam purge is to utilise a water heater  13  in the form of a flash (also known as an instantaneous or flow) heater. Typically such flash heaters comprise a tube through which the water passes wherein the tube is heated by one or more resistive elements. The flash heater can be used not only for heating water for forming beverages but also, at higher power settings, for generating a steam purge by boiling off water remaining with the flash heater tube after the beverage has been formed. An advantage of flash heaters is that there is no significant delay whilst water in a boiler heats up. Flash heaters heat water on demand and switch off immediately after each brewing cycle and are therefore very energy efficient. 
     Water output from the heater  13  is fed via a suitable delivery system to the cartridge head  17  and cartridge  100  by means of a valve. If the pressure of the water flow is acceptable, the water is passed to the cartridge  100 . If the pressure is below or above predetermined limits then the water is diverted by means of the valve to a waste recovery receptacle. 
     The delivery system comprises conduits which connect the tank  12 , the water pump  14 , the water heater  13  and the cartridge head  17  (as shown in  FIG. 8 ) to transport the water from the tank  12  to the cartridge  100 . 
     The cartridge holder  18  is designed to be capable of handling the opening forces generated by the pressure inside the cartridges  100 , which is around 250 kg for espresso beverages. During operation of the machine  10  the cartridges  100  attempt to expand, but the integrity of the cartridges  100  must be maintained. In addition the user must not be able to open the holder  18  whilst the system is pressurised and suitable locking mechanisms are provided to achieve this. 
     One suitable design of cartridge head  17 , as described in WO-A-2006/014936, is shown in  FIGS. 4 to 7 . The cartridge holder  18  of the cartridge head  17  comprises a fixed lower part  43 , a rotatable upper part  44  and a pivotable cartridge mount  45  positioned between the fixed lower part  43  and the rotatable upper part  44 . The upper part  44 , lower part  43  and cartridge mount  45  are rotated about a common hinge axis  46 .  FIGS. 4 to 7  show the holder  18  with some components of the machine  10  omitted for clarity. 
     The rotatable upper part  44  and pivotable cartridge mount  45  are moved relative to the fixed lower part  43  by means of a clamping mechanism. The clamping mechanism comprises a clamping lever having first and second members or parts  47  and  48 . The first part  47  of the clamping lever comprises a U-shaped arm which is pivotably mounted to the upper part  44  at two first pivot points  48 , one on each side of the holder  18 . 
     The second part of the clamping lever comprises two over-centre arms  49 , one on each side of the holder  18  which are each pivotably mounted to the upper part  44  at a second pivot point  50  located on the hinge axis  46  coupling the upper part  44  to the fixed lower part  43 . Each over-centre arm  49  is a reciprocal member comprising a cylinder  49   a , a stem  49   b  and a resilient sleeve  49   c . The cylinder  49   a  has an internal bore and is rotatably mounted at one end at the hinge axis  46 . A first end of the stem  49   b  is slidingly received in the bore of the cylinder  49   a . The opposite end of the stem  49   b  is rotatably mounted to the U-shaped arm  47  at a third pivot point  51 . The third pivot points  51  are unconnected to, and freely moveable relative to, the upper part  44  and lower part  43 . The resilient sleeve  49   c  is mounted externally on the stem  49   b  and extends, in use, between abutment surfaces on the cylinder  49   a  and stem  49   b . The resilient sleeve  49   c  accommodates shortening of the over-centre arm  49  but biases the over-centre arm  49  into an extended configuration. Movement of the third pivot points  51  towards and away from the hinge axis  46  is thus possible by relative movement of the stems  49   b  in the cylinders  49   a . The resilient sleeves  49   c  are preferably formed from silicone. Whilst the illustrated embodiment uses two over-centre arms  49 , it will be apparent that the closure mechanism may be configured with only one over-centre arm  49 . 
     The U-shaped arm  47  extends around the front of the holder  18  and comprises two downwardly dependant hook members  52 , one on each side of the holder  18 , each comprising a cam surface facing the hinge axis  46 . The fixed lower part  43  of the holder  18  is provided with two bosses  53 , or detents, located one on each side of the lower part  43  at or near a front edge  54  thereof aligned generally with the hook members  52 . 
     As shown in  FIG. 4 , the U-shaped arm  47  may be formed from a one piece plastics moulding comprising an ergonomic hand grip and the hook members  52  integral to the arm  47 . 
     The cartridge mount  45  is rotatably mounted between the upper and lower parts  43 ,  44  of the holder  18 . The mount  45  is provided with a substantially circular recess  55  which receives in use the beverage cartridge  100  (which is described in greater details below). The recess  55  includes an irregularity  56  for accommodating the handle portion  24  of the beverage cartridge  100  which also acts to prevent rotation of the beverage cartridge  100  in the holder  18 . The cartridge mount  45  is sprung relative to the fixed lower part  43  such that in the open position, as shown in  FIG. 7 , the cartridge mount  45  is biased out of contact with the fixed lower part  43  so that the cartridge mount  45  is moved out of contact with the outlet and inlet piercer members  21 ,  22 . The cartridge mount  45  is provided with an aperture  57  for receiving there through the inlet and outlet piercers  21 ,  22  and a head of the cartridge recognition means  20  when the cartridge mount  45  is moved into the closed position. 
     The upper part  43  comprises a generally circular body  58  housing a circular viewing window  59  through which a consumer can view the beverage cartridge  100  during a dispense cycle and also visually confirm whether a cartridge  100  is loaded in the machine  10 . The viewing window  59  is cup-shaped having a downwardly directed rim. In addition, the viewing window  59  is provided with a clamping member in the form of an inwardly directed tubular extension  61  as shown in  FIG. 7 . The extension  61  is directed towards the lower part  44  and lies within the volume of the cartridge head when in the closed position as shown in  FIG. 6 . The viewing window  59  is able to move axially relative to the housing  58  of the upper part  43 . One arrangement of accomplishing the relative movement is to provide a wave spring (not shown), or similar resilient means such as a rubberised ring, positioned between the viewing window  59  and the circular housing  58 . In an alternative arrangement, a series of helical compression springs (not shown) are provided extending between the viewing window  59  and the housing  58 . In both cases the resilient means allows the viewing window  59  to move axially relative to the circular housing  58  by a small degree. 
     When the holder  18  is in the closed position, a distal end  62  of the tubular extension  61  of viewing window  59  bears against the clamping surface  18   a  of the beverage cartridge  100  biasing it against the lower part  44  as shown in  FIG. 6  (in which the arrangement is illustrated containing a cartridge having a greater depth). The pressure exerted by the tubular extension  61  on the outer member  102  ensures a fluid tight seal between the cartridge  100  and the holder  18 . It should be noted that the height of the viewing window  59 , and hence also the cartridge head  17 , is such that cartridges  100  of various depths can be inserted. In  FIG. 6  the arrangement is shown with a relative deep cartridge. The same cartridge head  17  can also accommodate shallower cartridges. In this case there will be a gap between the upper surface  11  of the cartridge  100  and the window  59 . However the cartridge  100  is fully sealed at inlet and outlet by the pressure applied by the tubular extension  61 . 
     The lower part  43  comprises the inlet and outlet piercers  21 ,  22  and the head of the cartridge recognition means  20 . The inlet piercer  21  comprises a hollow needle-like tube  63  having a sharpened end  64  for perforating the laminate  108  of the beverage cartridge  100  in use. The inlet piercer  21  is in fluid communication with a water conduit  65 , as shown in  FIG. 7 , which passes through the lower part  43  and is connected to an outlet conduit  66  of the water heater  13 . The outlet piercer  22  is similar in type to the outlet piercer described in the EP-A-0389141 and EP-A-0 334572 and comprises an open ended cylinder of circular or D-shaped cross-section having dimensions larger than the beverage discharge spout  109 . An arcuate portion  67  of the upper end of the outlet piercer  22  is serrated to pierce and eventually cut the laminate of the beverage cartridge  100 . The remainder of the upper end is cut back longitudinally of the cylinder at least to the base of the teeth  68  of the serrated portion to fold or pull the cut laminate  108  away from the outlet aperture before the beverage is dispensed there through. The outlet piercer  22  pierces the laminate  105  externally of the discharge spout  143  and when the cartridge mount  45  is in the closed position, rests in the annulus between the discharge spout  143  and the outer wall  42  of the discharge funnel  140 . The outlet piercer  22  folds back the cut laminate  105  into the annulus. Thereby both the outlet piercer  22  and the cut laminate  105  are held out of the way of the discharged beverage. 
     The outlet piercer  22  is surrounded by a ledge which is raised relative to its surroundings by 0.5 mm. 
     Advantageously, the outlet piercer  22  is removable from the lower part  43  to enable it to be thoroughly cleaned, for example, in a dishwasher. The removable outlet piercer  22  is received in a recess in the lower part  43  where it is seated. The inlet piercer  21  and/or the outlet piercer  22  may be made of a metal, such as stainless steel, or from a plastics material. Advantageously, the use of plastic cutting elements is enabled by use of a laminate  105  which is able to be punctured and cut by a non-metallic material. Consequently, the piercers  21 ,  22  can be made less sharp which lowers the risk of injury to the consumer. In addition, plastic piercing elements are not prone to rust. Preferably, the inlet piercer  21  and the outlet piercer  24  are formed as a single, integral unit which is removable from the lower part  43 . 
     In use, the upper part  44  of the holder  18  is movable from an open position in which it is orientated vertically or towards the vertical as shown in  FIG. 2 , to a closed position in which it is orientated substantially horizontally and in interengagement with the fixed lower part  43  and cartridge mount  45 . The upper part  44  is moved from the open to the closed positions by operation of the clamping lever. To close the upper part  44  a user takes hold of the clamping lever by the U-shaped arm  47  and pulls downwards. Consequently, the upper part  44  rotates which first brings the tubular extension  61  of the viewing window  59  into contact with the clamping surface  118   a  of the beverage cartridge  100 . Continued rotation of the upper part  44  rotates the upper part  44  and cartridge mount  45  down into contact with the lower part  43 . Further rotation of the U-shaped arm  47  causes the U-shaped arm  47  to rotate relative to the upper part  44  and the lower part  43  resulting in the hook members  52  of the upper part  44  engaging the bosses  53  of the lower part  43  with the cam surface riding over the bosses  53 . During this last stage of rotation the cartridge  100  is compressed between the cartridge mount  45  and the viewing window  59 . As a result, the viewing window  59  is moved axially slightly relative to the circular housing  58  of the upper part  44  against the bias of the wave spring or helical springs. This movement allows for a take up of tolerances in the beverage cartridge  100  and beverage preparation machine  10  and ensures that the amount of compressive force applied to the cartridge  100  is kept within an acceptable range. The clamping force of the mechanism as moderated by the action of the wave spring or helical springs ensures a clamping pressure on the cartridge  100 . It has been found that a force of between 150N and 400N is required to counter the pressure in the cartridge  100 . During closure of the cartridge head the laminate  105  of the cartridge  100  is tensioned as it is brought into contact with the ledge surrounding the outlet piercer  22  which causes the laminate  105  to flex out of plane as the distal end of the outer tube  42  of the cylindrical funnel is moved upwardly by 0.5 mm relative to the flange  147 . This movement also ensures that the great majority of the compressive force applied to the cartridge  100  acts through the central region of the cartridge  100  through the load-bearing inner member  103 . These clamping forces help prevent failure of the cartridge  100  during pressurisation and also ensure that the inner member  103  and outer member  102  are fully seated relative to one another and thus that all internal passageways and apertures remain at their intended dimensions even during internal pressurisation. 
     In the closed position, the separation of the distal end  62  of the tubular extension  61  and the lower part  44  is shown by reference D in  FIG. 6 . This distance is fixed by the dimensions of the viewing window  59 , housing  58  and lower part  44 . The distance D is chosen to be the same or marginally smaller than the distance d between the clamping surface  118   a  and laminate  105  under surface of the cartridges  100 . In this way, on closure of the cartridge head  17  the cartridges  100  are subjected to a fixed, known degree of compression. In addition, both the first and second embodiments of cartridge can be clamped with the same degree of compression since distance D is the same for both cartridge types. 
     An imaginary datum line can be drawn between the first and second pivot points  48 ,  50  of the holder  18 . As can be seen in  FIG. 7 , in the open position the third pivot points  51  are located on the side of the datum line nearest the fixed lower part  43 . As the upper part  44  reaches the closed position, the third pivot points  51  of the clamping lever pass through the datum line joining the first and second pivot points  48 ,  50  to the opposite side of the line, furthest from the fixed lower part  43 . Consequently, the U-shaped arm  47  ‘snaps through’ from a first stable position to a second stable position. The snap through action is accommodated by shortening of the over-centre arms  49  and consequential compression of the resilient sleeves  49   c . Once the third pivot points  51  are past the imaginary datum line, the recovery of the resilient sleeves  49   c  acts to continue the motion of the third pivot points  51  away from the imaginary datum line. The clamping lever thus has a bi-stable operation in that the lever is stable in the open or closed positions but unstable at the point when the third pivot points  51  lie on the imaginary datum line joining the first and second pivot points  48 ,  50 . Thus, the snap-through action of the clamping lever provides a positive closure mechanism which leads to a definite closure action wherein in the final stages of the clamping lever&#39;s rotation, the snap-through action of the U-shaped arm  47  and second arms forces the hook members  52  firmly into engagement with the bosses  53 . In addition, the resilient sleeves  49   c  provide a resistance to re-opening of the upper part  44  since a minimum force is required to compress the sleeves  49   c  sufficiently to move the third pivot points  51  back into line with the datum line joining the first and second pivot points  48 ,  50 . Advantageously, the interengagement of the hook members  52  and the bosses  53  prevents separation of the upper and lower parts other than by rotation of the clamping lever. This is useful in preventing opening of the cartridge head  17  during operation when the cartridge head  17  is subject to internal pressurisation. 
     The pressure exerted by the upper section  44  ensures a full fluid tight seal between the cartridge  100  and the cartridge holder  18 . The clamping forces help prevent failure of the cartridge  100  during pressurisation and also ensure that all of the internal passageways and apertures within the cartridge  100  remain at their intended dimensions even during internal pressurisation. To improve the seal with the cartridges  100  the applicant has now found that lining the recess  55  of the cartridge mount  45  with a rubber seal  55   a  (see  FIG. 7 a   ) improves the machine&#39;s ability to withstand the significantly higher pressures generated during the brewing cycle. 
     Control of the brew cycle is effected by the control processor of the beverage preparation machine  10 , which comprises a processing module and a memory. The control processor is operatively connected to, and controls operation of, the heater  13 , pump  14 , user interface  16 , and other components described below. 
     The operational behaviour of the machine  10  is determined by software embedded in the control processor, for example as described in EP-A-1440644. The memory of the control processor includes one or more variables for one or more operational parameters for the beverage preparation machine  10 . In the prior art machines these are generally the temperature of the liquid passed through the beverage cartridge  100  during the operating stage, the speed of charging the beverage cartridge  100 , the presence or otherwise of a soak step, the total dispensed volume of the beverage, the flow rate of the liquid during the discharge stage, and the period of the purge stage. 
     One purpose of the cartridge recognition means  20  is, inter alia, to allow the machine  10  to recognise the type of beverage cartridge  100  that has been inserted and to adjust one or more operational parameters accordingly. The variables for the operational parameters are stored in the memory. The cartridge  100  comprises a code  120  provided on or in the cartridge  100  representing the operational parameters required for optimal dispensation of the beverage in that cartridge  100 . An example of the code is described in EP-A-1440644. 
     The control processor memory further stores information on the type of beverage dispensed so that the operating cycle of the machine  10  may be adjusted for the next cartridge  100 . This is especially advantageous where two or more beverage cartridges  100  are used sequentially to form a beverage. For example a coffee cartridge may be dispensed followed by a milk cartridge to form a cappuccino beverage. Alternatively a chocolate cartridge could be used followed by a milk cartridge to produce a creamy hot chocolate beverage. By using a memory that stores information on the first beverage dispensed, the manner of dispensing the second cartridge, say a milk cartridge, may be altered to achieve an optimum beverage. In the above example the milk dispensed for hot chocolate may, typically, be diluted less than the milk added to the coffee. In addition, the milk dispensed for chocolate may be dispensed at a slower flow rate to lessen the degree of foaming of the beverage. Many combinations of cartridges are possible and operating parameters as will be obvious to the skilled person. In addition, the memory may be used to allow the machine  10  to ‘predict’ the type of beverage that a user will next want to dispense. For example, if a user predominantly drinks one beverage type then the machine can instruct the water heater to remain at the optimum temperature for that beverage type. 
     Operation of the known prior art machines  10  comprises insertion of a beverage cartridge  100  into the cartridge head  17 , carrying out a dispense cycle in which the beverage is dispensed and removal of the cartridge  100  from the machine. 
     To insert the cartridge  100  the cartridge holder  18  is opened as described above to expose the cartridge mount  45 . The cartridge  100  is then placed on the cartridge mount  45  received within the recess  46 . The cartridge holder  18  is then closed by operation of the clamping handle  51  as described above. During closure the inlet and outlet piercers pierce the cartridge  100  to form the cartridge inlet  107  and outlet  108 . 
     To commence the operating cycle the user operates the start/stop button  28 . The operating cycle comprises the steps of cartridge recognition and the beverage preparation cycle. 
     Cartridge recognition is performed by the optical cartridge recognition means  20  as described above assuming that the outputs from the cartridge sensor and lock sensor are satisfactory. Once the barcode  40  has been decoded the operational parameters of the machine  10  are adjusted by the control processor. The preparation cycle is then automatically commenced. The preparation cycle has four main stages, although not all of these are used for all beverage types: 
     1. Pre-wet 
     2. Pause 
     3. Brew stage 
     4. Purge 
     In the pre-wet stage the cartridge  100  is charged with liquid from the storage tank  12  by means of the pump  14 . The charging with water causes the beverage ingredients  200  in the chamber  160  to be wetted. The charging may take place at a “fast” flow rate of 600 ml/min or a “slow” flow rate of 325 ml/min. The slow charging rate is particularly useful for cartridges  100  containing viscous liquid beverage ingredients where the ingredients require some dilution before they are able to be pumped at a higher volume flow rate. The volume of liquid injected into the cartridge  100  is selected to ensure that liquid or beverage does not drip out of the cartridge outlet  108  during this stage. 
     The pause stage allows the beverage ingredients  200  to soak in the liquid injected during the pre-wet stage for a predetermined period of time. Both the pre-wetting and soaking stages are known to increase the yield of the extractibles from the beverage ingredients  200  and to improve the end flavour of the beverage. Pre-wetting and soaking are particularly used where the beverage ingredients are roast and ground coffee. 
     In the brew stage liquid is passed through the cartridge  100  in order to produce the beverage from the beverage ingredients  200 . The temperature of the liquid is determined by the control processor which sends instructions to the heater  13  to heat the liquid passing from the tank  12  to the cartridge head  17 . Liquid enters the cartridge holder  18  via an inlet valve and the inlet piercer and then passes into the inlet chamber  126  of the beverage cartridge  100 . Brewing and/or mixing of the beverage in the beverage cartridge  100  occurs, as described in EP-A-1440644, before the prepared beverage exits the cartridge outlet  104 , enters the outlet valve  37  and is directed into a suitably placed receptacle in the dispensing station  27 . 
     During the purge cycle the temperature of the water heater  13  is raised sufficiently high to convert the water remaining in the system to steam and blowing the pressurised steam through the beverage preparation machine  10  and the beverage cartridge  100 . This ensures that all beverage is dispensed and that the flow path is cleared ready for dispensing another beverage. The purge cycle may not commence immediately on cessation of the brew/mixing stage to allow for the majority of the fluid to clear the flow path. 
     Once the operating cycle has been completed, the machine automatically stops and the consumer removes the cartridge  100  by opening the cartridge holder  18  and manually removing and disposing of the cartridge  100 . Alternatively, the machine  10  may be provided with an automatic ejection mechanism for removing the cartridge automatically on opening the cartridge holder  18 . 
     The first of the significant improvements to the known beverage preparation machines  10  referred to above is the provision of variable geometry valve  60  (see  FIGS. 9 to 15 ) provided adjacent the cartridge outlet  108  to provide post-cartridge pressure control. This enables the machine  10  to produce a wide variety of beverages, as it allows the cartridges  100  to be selectively brewed at either high or low pressure or a varying pressure during the brew cycle, depending on the type of brew cycle required for the beverage ingredients in the cartridge as identified by the cartridge recognition means  20 , thus providing an automated variable pressure system. The modified machine is capable of producing beverages at a range of pressures, for example from 0 to 9 bar, and more preferably from 0 to 6 bar. 
     The variable geometry valve  60  is positioned downstream of the cartridge  100 , and preferably positioned in the beverage outlet  37 , which is partially housed in, and extends from, the lower section  43  of the cartridge head  17  (see  FIGS. 6 and 7 ). The valve  60  has at least an open and a restricted state, and more preferably all of the states identified below:— 
     1. Open ( FIG. 11 ) 
     2. Restricted ( FIG. 12 ) 
     3. Closed ( FIG. 10 ) 
     4. Cleaning/purging. 
     Various types of valve may be used for the outlet valve  60 , such as ball valves, pinch valves, sleeve valves, seat valves or disc valves. The embodiment illustrated in  FIGS. 10 to 12  is a ball type valve which has a rotating element  69  located in a chamber  70  in the beverage outlet  37 . The rotating element  69  is rotatable between preset positions to provide the required states. The diameter of the bore of the valve  60  in the unrestricted position is preferably at least 5 mm which is required, for example, for cartridges  100  providing low pressure filter beverages. 
     An alternative suitable valve is a pinch valve illustrated in  FIGS. 13 to 15  which comprises a flexible tube  71 , preferably made of silicon rubber or an elastomeric material, and a clamping mechanism  72 . In the unrestricted position ( FIGS. 13 a    and  14 ) the beverage flows freely through the tube  71 . The clamping mechanism  72  is activated to provide a restricted position ( FIGS. 13 b    and  15 ) and closed position. 
     The valve  60  is controlled automatically by the control processor of the machine  10 . Once the type of cartridge  100  inserted into the machine  10  has been identified, by the decoding the barcode  40 , the control processor selects the correct initial setting and, if appropriate, any subsequent operation of the valve  60  for the relevant beverage type. 
     The machine  10  can operate in a range of modes, with the valve  60  in one or more positions, some examples of which are:— 
     1. Valve Open Throughout the Brewing Cycle 
     When the valve  60  is in its open position the operating pressure is below 2 bar allowing a steady state through flow rate of up to 400 ml/min. The beverage is dispensed under similar conditions to those described in EP-A-1440644. This mode is particularly useful as it renders the machine  10  backwardly compatible with existing cartridges for preparing low pressure beverages, such as tea, foamed milk or chocolate. 
     2. Valve Restricted Throughout the Brewing Cycle 
     When the valve  60  is in its restricted position it creates a relatively high back pressure within the cartridge  100 , which results in an operating pressure of up to 4, 6 or even 9 bar and provides a steady state through flow rate of 60 to 300 ml/min. This is sufficient to obtain the necessary solids extraction and emulsification of oils in the beverage ingredients  200  for an espresso beverage. The consequential restriction in the beverage outlet  37  provides a shearing and mixing action in the beverage flowing through the valve  60 , giving rise to good air/liquid emulsification and resulting in an improved crema. This mode can advantageously be used for preparing higher pressure beverages, such as espressos and cappuccinos, from cartridges  100  which do not have means for entraining air to effect the mixing action, i.e. so called non-eductor cartridges. 
     3. Valve Closed then Restricted 
     If the valve  60  is closed immediately at the start of the brewing cycle (before the pump  14  commences and during the pre-wet cycle), this enables a higher pressure to be developed within the cartridge  100  than when the valve  60  is in it&#39;s restricted position. 
     Further combinations may be appropriate, such as valve closed then open or valve closed then restricted then open according to the desired effect to be achieved. 
     If required, the valve  60  can be pulsed between various positions during the brewing cycle, or a part thereof. This manner of valve operation during the delivery cycle enables beverages with a crema having a graduated colour and/or bubble size to be produced. 
     During the purge cycle the valve  60  is controlled by the control processor to divert the steam to a drain area rather than to the dispensing station  27  to preserve the appearance of the beverage and prevent contamination. 
     The second of the significant improvements to the known beverage preparation machines  10  referred to above is the addition to the brew control system of gas management. Surprisingly the applicant has now discovered that the characteristics of beverages prepared in this type of beverage preparation machine  10  can be modified beyond boundaries hereto seen in prior art machines. The surprising effect is enacted by controlling the volume of gas in the delivery system during the preparation of the beverage to prescribe the amount of high quality crema resulting in a controlled amount of crema on a beverage varying from a delicate layer up to a surprisingly deep layer in the final beverage. The applicant has found a way to successfully use gases within the beverage preparation machine to modify the gas:liquid ratio to produce a surprising volume of good stable crema in prepared beverages never seen before in prior art machines. Maintaining a greater volume of gas resident in the delivery system enables a much larger gas:liquid ratio to be achieved during brewing and dispensing and this produces a correspondingly larger volume of crema. Decreasing the volume of gas enables the ratio to be decreased to reduce the crema volume. The bubble size is also influenced by the gas:liquid ratio, so a lower ratio can be used to provide a tight and creamy crema and a higher ratio used to provide a more loose and bubbly crema. This improvement therefore provides the ability to optimise the crema volume and bubble size for each beverage dispensed. It has been found that by manipulating the gas good quality espressos can be brewed with a crema volume greater than 25% of the beverage volume whilst minimising the occurrence of bubbles having a diameter of more than 172 microns which is not previously seen to be possible in known beverage preparation machines of this type. 
     The improvement is achieved by adapting the control of the brew cycle to provide means for managing the volume of gas within the delivery system which conveys the water from the tank  12  to the beverage ingredients  200  and to the dispensing outlet. All further references in this specification to the delivery system are intended to include any predetermined section thereof, for example the section extending from the water heater  13  to the cartridge  100  and may also include, if relevant, some gas contained within a headspace of the cartridge  100 . 
     The “basic volume” of gas which can reside within the delivery system of any given machine  10  is dependant on its construction. The “actual volume” at any given time will vary according to whether the machine  10  has just been used to prepare a beverage, what type of beverage it was used for and whether a steam purge cycle has been run. Thus the improved brew cycle control incorporates means for varying the volume of gas in the delivery system according to the type of beverage to be dispensed (i.e. one requiring a crema with smaller and fewer bubbles or one which requires a greater froth of larger bubbles) taking into account the actual volume of gas already present. The means for varying the volume of gas may be achieved by combinations of:— 
     1. purging the delivery system after a brewing cycle is complete, and prior to a subsequent high pressure brew, which will increase the gas:liquid ratio; 
     2. venting gas from the delivery system prior to high pressure brewing, which will decrease the gas:liquid ratio; and 
     3. inducting gas into the delivery system prior to high pressure brewing, which will increase the gas:liquid ratio. 
     Valve means are preferably provided to enable the volume of gas within the delivery system to be reduced and an air pump to enable gas (typically air) to be injected into the system. A separate, dedicated air valve may be incorporated in the delivery system, either upstream or downstream of the cartridge  100 . Preferably the variable geometry valve  60  described above may be used as the valve means. 
     To enable this improved brew cycle control to be effected, additional parameters to those described in connection with the basic machine  10  may be stored in the memory of the control processor. These additional parameters include the basic volume of gas for the specific construction of machine  10  (which will apply to the machine  10  which is unused or after it has been purged) and the volume required during high pressure brewing for optimising the crema for each specific beverage. Preferably the additional parameters also include the actual volume of gas which will remain in the delivery system after each type of brew operation which the machine  10  is capable of. However this is not wholly necessary if the machine  10  is programmed to run a steam purge cycle after every beverage is dispensed, which effectively resets the actual volume to the basic volume, because it flushes the dispensing system downstream of the water heater  13  of any remaining liquid. 
     The brew cycle will therefore include an additional step, namely a gas adjustment cycle before the pre-wet cycle. The gas adjustment cycle thus includes:— 
     1. An assessment of the required volume of gas for the type of beverage to be prepared. This will most conveniently be the selection from the processor memory of the required parameter associated with the cartridge code  120 ; 
     2. The determination of the actual volume of gas currently resident in the delivery means according to the last operation of the machine  10 . This will be the basic volume for an unused machine or if a purge cycle has been run. If the machine has just been used to prepare a beverage and no purge cycle run, the processor ideally selects from the memory the parameter for the remaining gas according to the last beverage. Alternatively, means may also be provided to specifically monitor the volume of gas within the delivery system at any point in time; 
     3. A calculation of the volume of gas to be inducted into or vented from the delivery system to achieve the required volume; 
     4. The modification of the volume of gas, if required, by the induction of additional gas (typically air) or the venting of excess gas. 
     In one example the beverage preparation machine  10  has a basic volume of gas of 36 ml in the section of the delivery means extending between the water heater  13  and the beverage ingredients  200 . 
     There are a number of different modes of operation for step  4  depending on the outcome of step  3 , depending on what type of valve means are used. If the valve means are downstream of the cartridge, i.e. an outlet valve, one way of controlling the volume of air upstream of the beverage ingredients  200  prior to high pressure brewing is by closing the outlet valve at different points in the brew cycle as follows:— 
     1. The Correct Volume of Gas is Present 
     If the processor calculates that it requires the full basic volume of gas (36 ml) for the beverage to be dispensed, as determined from the reading of the code  120 , it closes the outlet valve at the start of the brew cycle, before any water flows from the water heater  13 . This means that the compression of gas in the delivery system will commence immediately and the cartridge  100  will be subject to higher pressures during the pre-wet and soak cycles, with the valve only opening to dispense the resultant beverage. As the outlet valve is closed before the pump  14  is started, all of the 36 ml of trapped gas is mixed in to the resulting beverage and a larger volume of slightly coarser crema is obtained ( FIG. 16 a   ). In the example shown the volume of crema Y in a graduated glass, flat bottomed beaker was 20 ml compared to the volume of liquid X, which was 50 ml. 
     The chart shown in  FIG. 16 b    represents an example of brew cycle parameters used to produce a beverage in this mode with a large volume of crema under test conditions. 
     In this chart, a stop condition of 0 seconds (e.g. against the remove gas step) indicates that the step is not carried out. 
     2. Too Much Gas is Present 
     If, on the other hand, a beverage with a small volume of crema is indicated by the cartridge  100  inserted and there is an excess of gas present in the system, the outlet valve is closed after the pump  14  has operated for a short time until the excess gas in the delivery system has escaped through the open valve at low pressure. With the valve being closed later in the brew cycle, the required volume of gas is vented to atmosphere via the cartridge  100  and valve, so a smaller quantity of trapped gas is left to be compressed and mixed in to the resulting beverage during high pressure brewing and consequently a smaller volume of finer crema is obtained ( FIG. 17 a   ). In the example shown the volume of crema Y in a graduated glass, flat bottomed beaker was 5 ml compared to the volume of liquid X, which was 50 ml. 
     The chart shown in  FIG. 17 b    represents an example of brew parameters used to produce a beverage in this mode with a small volume of crema under test conditions. 
     3. Insufficient Gas Present 
     If step  3  indicates that more gas needs to be inducted, the outlet valve is closed immediately and the air pump operated until the deficit has been made up. Thereafter high pressure brewing commences. 
     The following graph is a digital image analysis showing a comparison of the crema characteristics produced by the present beverage preparation machine  10  (machine A) utilising the gas management system and two prior art machines (machines B and C) without such gas management system. Comparing the profiles for each machine from the peak (˜172 μm diameter) rightwards (increasing bubble size), it can be seen that machine A exhibits a very tight distribution of small bubbles within the crema. Machine C (the Nespresso Latissma™) which is a high pressure machine which has a pressure rating of around 19 bar and operates at a pressure between 9 and 15 bar) produces a broader/coarser distribution with a number of larger diameter bubbles, whilst machine B (the applicant&#39;s own Tassimo/Bosch Machine™) similar to that described in EP-A-1440644 which is a low pressure machine operating at pressures below 2 bar) is coarser still, though without the larger bubbles seen for machine C. 
     The tail to the left of the chart (extremely small bubbles) is characteristic of the limits of the image analysis systems used to produce the graph, though is qualitatively similar. 
     Some elements of the control of the gas in the beverage machine  10  may also be effected manually by the use of suitable buttons for the user to press, to indicate the type of beverage being produced and the required crema characteristics. 
     Whilst this improvement has been described with reference to beverage machines  10  which use cartridges  100 , it may also be used in bulk brewers and other non-cartridge machines. 
     Embodiments of cartridges  100  which are suitable for use in the machine  10  having the improvements described above are shown in  FIGS. 18 to 30 . 
     The cartridge  100  generally comprises an outer member  102 , an inner member  103  and a laminate  105 . The outer member  102 , inner member  103  and laminate  105  are assembled to form the cartridge  100  which has an interior  106  for containing one or more beverage ingredients, an inlet  107 , an outlet  108  and a beverage flow path linking the inlet  107  to the outlet  108  and which passes through the interior  106 . The inlet  107  and outlet  108  are initially sealed by the laminate  105  and are opened in use by piercing or cutting of the laminate  105 . The beverage flow path is defined by spatial inter-relationships between the outer member  102 , inner member  103  and laminate  105  as discussed below. Other components may optionally be included in the cartridge  100 , such as a filter  104 , as will be described further below. 
     A first version of cartridge  100  which will be described is shown in  FIGS. 19 to 29 . The first version of the cartridge  100  is particularly designed for use in dispensing espresso-style products such as roast and ground coffee where it is desirable to produce a crema. However, this version of the cartridge  100  may be used with other products such as chocolate, coffee, tea, sweeteners, cordials, flavourings, alcoholic beverages, flavoured milk, fruit juices, squashes, sauces and desserts. 
     As can be seen from  FIG. 23 , the overall shape of the cartridge  100  is generally circular or disc-shaped with the diameter of the cartridge  100  being significantly greater than its height. A major axis X passes through the centre of the outer member as shown in  FIG. 19 . Typically the overall diameter of the outer member  102  is 74.5 mm±6 mm and the overall height is 16 mm±3 mm. Typically the volume of the cartridge  100  when assembled is 30.2 ml±20%. 
     The outer member  102  generally comprises a bowl-shaped shell  110  having a curved annular wall  113 , a closed top  111  and an open bottom  112 . The diameter of the outer member  102  is smaller at the top  111  compared to the diameter at the bottom  112 , resulting from a flaring of the annular wall  113  as one traverses from the closed top  111  to the open bottom  112 . The annular wall  113  and closed bottom  112  together define a receptacle having an interior  134 . 
     A hollow inwardly directed cylindrical extension  118  is provided in the closed top  111  centred on the major axis X. As more clearly shown in  FIG. 20 , the cylindrical extension  18  comprises a stepped profile having first, second and third portions  119 ,  120  and  121 . The first portion  119  is right circular cylindrical. The second portion  120  is frusto-conical in shape and is inwardly tapered. The third portion  121  is another right circular cylinder and is closed off by a lower face  131 . The diameter of the first, second and third portion  119 ,  120  and  121  incrementally decreases such that the diameter of the cylindrical extension  118  decreases as one traverses from the top  111  to the closed lower face  131  of the cylindrical extension  118 . A generally horizontal shoulder  132  is formed on the cylindrical extension  118  at the junction between the second and third portions  120  and  121 . 
     An outwardly extending shoulder  133  is formed in the outer member  102  towards the bottom  112 . The outwardly extending shoulder  133  forms a secondary wall  115  co-axial with the annular wall  113  so as to define an annular track forming a manifold  116  between the secondary wall  115  and the annular wall  113 . The manifold  116  passes around the circumference of the outer member  102 . A series of slots  117  are provided in the annular wall  113  level with the manifold  116  to provide gas and liquid communication between the manifold  116  and the interior  134  of the outer member  102 . As shown in  FIG. 21 , the slots  117  comprise vertical slits in the annular wall  113 . Between twenty and forty slots are provided. In the embodiment shown thirty-seven slots  117  are provided generally equi-spaced around the circumference of the manifold  16 . The slots  117  are preferably between 1.4 and 1.8 mm in length. Typically the length of each slot  117  is 1.6 mm representing 10% of the overall height of the outer member  102 . The width of each slot  117  is between 0.25 and 0.35 mm. Typically, the width of each slot  117  is 0.3 mm. The width of the slots  117  is sufficiently narrow to prevent the beverage ingredients passing there through into the manifold  116  either during storage or in use. 
     An inlet chamber  126  is formed in the outer member  102  at the periphery of the outer member  102 . A cylindrical wall  127  is provided, as most clearly shown in  FIG. 23 , which defines the inlet chamber  126  within, and partitions the inlet chamber  126  from, the interior  134  of the outer member  102 . The cylindrical wall  127  has a closed upper face  128  which is formed on a plane perpendicular to the major axis X and an open lower end  129  co-planar with the bottom  12  of the outer member  102 . The inlet chamber  26  communicates with the manifold  116  via two slots  130  as shown in  FIG. 19 . Alternatively, between one and four slots may be used to communicate between the manifold  116  and the inlet chamber  126 . 
     A lower end of the outwardly extending shoulder  133  is provided with an outwardly extending flange  135  which extends perpendicularly to the major axis X. Typically the flange  135  has a width of between 2 and 4 mm. A portion of the flange  135  is enlarged to form a handle  124  by which the outer member  102  may be held. The handle  124  is provided with an upturned rim  125  to improve grip. 
     The outer member  102  is formed as a single integral piece from high density polyethylene, polypropylene, polystyrene, polyester, or a laminate of two or more of these materials. A suitable polypropylene is the range of polymers available from DSM UK Limited (Redditch, United Kingdom). The outer member may be opaque, transparent or translucent. The manufacturing process may be injection moulding. 
     The inner member  103  as shown in  FIGS. 25 to 28 , comprises an annular frame  141  and a downwardly extending cylindrical funnel  140 . A major axis X passes through the centre of the inner member  103  as shown in  FIG. 25 . 
     As best shown in  FIGS. 26 and 27 , the annular frame  141  comprises an outer rim  151  and an inner hub  152  joined by ten equi-spaced radial spokes  153 . The inner hub  152  is integral with and extends from the cylindrical funnel  140 . Filtration apertures  155  are formed in the annular frame  141  between the radial spokes  153 . A filter  104  is disposed on the annular frame  141  so as to cover the filtration apertures  155 . The filter is preferably made from a material with a high wet strength, for example a non-woven fibre material of polyester. Other materials which may be used include a water-impermeable cellulosic material, such as a cellulosic material comprising woven paper fibres. The woven paper fibres may be admixed with fibres of polypropylene, polyvinyl chloride and/or polyethylene. The incorporation of these plastic materials into the cellulosic material renders the cellulosic material heat-sealable. The filter  104  may also be treated or coated with a material which is activated by heat and/or pressure so that it can be sealed to the annular frame  141  in this way. 
     As shown in the cross-sectional profile of  FIG. 25 , the inner hub  152  is located at a lower position than the outer rim  151 , resulting in the annular frame  141  having a sloping lower profile. 
     The upper surface of each spoke  153  is provided with an upstanding web  154  which divides a void space above the annular frame  141  into a plurality of passages  157 . Each passage  157  is bounded on either side by a web  154  and on a lower face by the filter  104 . The passages  157  extend from the outer rim  151  downwardly towards, and open into, the cylindrical funnel  140  at openings  156  defined by the inner extremities of the webs  154 . 
     The cylindrical funnel  140  comprises an outer tube  142  surrounding an inner discharge spout  143 . The outer tube  142  forms the exterior of the cylindrical funnel  140 . The discharge spout  143  is joined to the outer tube  142  at an upper end of the discharge spout  143  by means of an annular flange  147 . The discharge spout  143  comprises an inlet  145  at an upper end which communicates with the openings  156  of the passages  157  and an outlet  144  at a lower end through which the prepared beverage is discharged into a cup or other receptacle. The profile of the discharge spout  43  comprises a stepped profile with a distinct dog-leg  166  near an upper end of the tube  143 . 
     As shown in  FIG. 25 , the discharge spout  143  is provided with a partition  165  which extends part way up the discharge spout  143  from the outlet  144 . The partition  165  helps to prevent the beverage spraying and/or splashing as it exits the discharge spout  143 . 
     A rim  167  is provided upstanding from the annular flange  147  joining the outer tube  142  to the discharge spout  143 . The rim  167  surrounds the inlet  145  to the discharge spout  143  and defines an annular channel  169  between the rim  167  and the upper portion of the outer tube  142 . The rim  167  is provided with an inwardly directed shoulder  168 . At one point around the circumference of the rim  167  an aperture  170  is provided in the form of a slot which extends from an upper edge of rim  167  to a point marginally below the level of the shoulder  168  as most clearly shown in  FIGS. 25 and 25   a . The slot has a width of 0.64 mm. 
     An air inlet  171  is provided in annular flange  147  circumferentially aligned with the aperture  170  as shown in  FIGS. 28 and 28   a . The air inlet  171  comprises an aperture passing through the flange  147  so as to provide communication between a point above the flange  147  and the void space below the flange  147  between the outer tube  142  and discharge spout  143 . Preferably, and as shown, the air inlet  171  comprises an upper frusto-conical portion  173  and a lower cylindrical portion  172 . The air inlet  171  is typically formed by a mould tool such as a pin. The tapered profile of the air inlet  171  allows the mould tool to be more easily removed from the moulded component. The wall of the outer tube  142  in the vicinity of the air inlet  171  is shaped to form a chute leading from the air inlet  171  to the inlet  145  of the discharge spout  143 . As shown in  FIG. 28 a   , a canted shoulder  174  is formed between the air inlet  171  and the chute to ensure that the jet of beverage issuing from the slot  170  does not immediately foul on the upper surface of the flange  147  in the immediate vicinity of the air inlet  171 . 
     The inner member  103  may be formed as a single integral piece from polypropylene or a similar material as described above and by injection moulding in the same manner as the outer member  102 . 
     Alternatively, the inner member  103  and/or the outer member  102  may be made from a biodegradable polymer. Examples of suitable materials include degradable polyethylene (for example, SPITEK supplied by Symphony Environmental, Borehamwood, United Kingdom), biodegradable polyester amide (for example, BAK 1095 supplied by Symphony Environmental), poly lactic acids (PLA supplied by Cargil, Minn., USA), starch-based polymers, cellulose derivatives and polypeptides. 
     The laminate  105  is formed from two layers, a first layer of aluminium and a second layer of cast polypropylene. The aluminium layer is between 0.02 and 0.07 mm in thickness. The cast polypropylene layer is between 0.025 and 0.065 mm in thickness. In one embodiment the aluminium layer is 0.06 mm and the polypropylene layer is 0.025 mm thick. This laminate  105  is particularly advantageous as it has a high resistance to curling during assembly. As a result the laminate  105  may be pre-cut to the correct size and shape and subsequently transferred to the assembly station on the production line without undergoing distortion. Consequently, the laminate  108  is particularly well suited to welding. Other laminate materials may be used including PET/Aluminium/PP, PE/EVOH/PP, PET/metallised/PP and Aluminium/PP laminates. Roll laminate stock may be used instead of die cut stock. 
     The cartridge  100  may be closed by a rigid or semi-rigid lid instead of a flexible laminate  105 . 
     Assembly of the cartridge  100  involves the following steps: 
     a) the inner member  103  is inserted into the outer member  102 ; 
     b) the filter  104  is cut to shape and placed onto the inner member  103  so to be received over the cylindrical funnel  140  and come to rest against the annular frame  141 ; 
     c) the inner member  103 , outer member  102  and filter  104  are joined by ultrasonic welding; 
     d) the cartridge  100  is filled with one or more beverage ingredients; 
     e) the laminate  105  is affixed to the outer member  102 . 
     These steps will be discussed in greater detail below. 
     The outer member  103  is orientated with the open bottom  112  directed upwards. The inner member  103  is then inserted into the outer member  102  with the outer rim  151  being received as a loose fit in an axial extension  114  at top  111  of the cartridge  100 . The cylindrical extension  118  of the outer member  102  is at the same time received in the upper portion of the cylindrical funnel  140  of the inner member  103 . 
     The third portion  121  of the cylindrical extension  118  is seated inside the support rim  167 . The shoulder  132  of the cylindrical extension  118  between the second portion  120  and third portion  121  bears against the upper edge of the support rim  167  of the inner member  103 . An interface zone is thus formed between the inner member  103  and the outer member  102  comprising a face seal between the cylindrical extension  118  and the support rim  167  which extends around nearly the whole circumference of the cartridge  100 . The seal between the cylindrical extension  118  and the support rim  167  is not fluid-tight though since the slot  170  in the support rim  167  extends through the support rim  167  and downwardly to a point marginally below the shoulder  168 . Consequently the interface fit between the cylindrical extension  118  and the support rim  167  transforms the slot  170  into an aperture providing gas and liquid communication between the annular channel  169  and the discharge spout  143 . The aperture is typically 0.64 mm wide by 0.69 mm long. 
     The filter  104  is then placed over the inner member  103  such that the filter material contacts the annular rim  151 . An ultrasonic welding process is then used to join the filter  104  to the inner member  103  and at the same time, and in the same process step, the inner member  103  to the outer member  102 . The inner member  103  and filter  104  are welded around the outer rim  151 . The inner member  103  and outer member  102  are joined by means of weld lines around the outer rim  151  and also the upper edges of the webs  154 . 
     As shown most clearly in  FIG. 29 , the outer member  102  and inner member  103  when joined together define a void space in the interior  106  below the annular flange  141  and exterior the cylindrical funnel  140  which forms a filtration chamber. The filtration chamber  160  and passages  157  above the annular frame  141  are separated by the filter paper  104 . 
     The filtration chamber  160  contains the one or more beverage ingredients  200 . The one or more beverage ingredients  200  are packed into the filtration chamber  160 . For an espresso-style beverage the ingredient is typically roast and ground coffee. The density of packing of the beverage ingredients in the filtration chamber  130  can be varied as desired. Typically, for a filtered coffee product the filtration chamber contains between 5.0 and 10.2 grams of roast and ground coffee in a filtration bed of thickness of typically 5 to 14 mm. Optionally, the interior  106  may contain one or more bodies, such as spheres, which are freely movable within the interior  106  to aid mixing by inducing turbulence and breaking down deposits of beverage ingredients during discharge of the beverage. 
     The laminate  105  is then affixed to the outer member  102  by forming a weld  161  around the periphery of the laminate  105  to join the laminate  105  to the lower surface of the outwardly extending flange  135 . The weld  161  is extended to seal the laminate  105  against the lower edge of the cylindrical wall  127  of the inlet chamber  126 . Further, a weld  162  is formed between the laminate  105  and the lower edge of the outer tube  142  of the cylindrical funnel  140 . The laminate  105  forms the lower wall of the filtration chamber  160  and also seals the inlet chamber  126  and cylindrical funnel  140 . However, a small gap  163  exists prior to dispensation between the laminate  105  and the lower edge of the discharge spout  43 . A variety of welding methods may be used, such as heat and ultrasonic welding, depending on the material characteristics of the laminate  105 . 
     Advantageously, the inner member  103  spans between the outer member  102  and the laminate  105 . The inner member  103  is formed from a material of relative rigidity, such as polypropylene. As such, the inner member  103  forms a load-bearing member that acts to keep the laminate  105  and outer member  102  spaced apart when the cartridge  100  is compressed. It is preferred that the cartridge  100  is subjected to a compressive load of between 130 and 280N in use. The compressive force acts to prevent the cartridge failing under internal pressurisation and also serves to squeeze the inner member  103  and outer member  102  together. This ensures that the internal dimensions of passageways and apertures in the cartridge  100  are fixed and unable to change during pressurisation of the cartridge  100 . 
     In use the water, under pressure, enters the cartridge  100  through the inlet  107  into the inlet chamber  126 . From there the water is directed to flow through the slots  117  and round the manifold  116  and into the filtration chamber  160  of the cartridge  1  through the plurality of slots  117 . The water is forced radially inwardly through the filtration chamber  160  and mixes with the beverage ingredients  200  contained therein. The water is at the same time forced upwardly through the beverage ingredients  200 . The beverage formed by passage of the water through the beverage ingredients  200  passes through the filter  104  and filtration apertures  155  into the passages  157  lying above the annular frame  141 . 
     Beverage in the radial passages  157  flows downwardly along the passages  157  formed between the webs  154  and through the openings  156  and into the annular channel  169  of the cylindrical funnel  140 . From the annular channel  169  the beverage is forced under pressure through the aperture  128  by the back pressure of beverage collecting in the filtration chamber  160  and passages  157 . The beverage is thus forced through aperture as a jet and into an expansion chamber formed by the upper end of the discharge spout  143 . As shown in  FIG. 29 , the jet of beverage passes directly over the air inlet  171 . Passage of the beverage through the restriction of the aperture causes the pressure of the beverage to be reduced. As the beverage enters the discharge spout  143  the pressure of the beverage is still relatively low. As a result air is entrained into the beverage stream in the form of a multitude of small air bubbles as the air is drawn up through the air inlet  171 . The jet of beverage issuing from the aperture is funneled downwards to the outlet  144  where the beverage is discharged into a receptacle such as a cup where the air bubbles form the desired crema. Thus, the aperture and the air inlet  171  together form an eductor which acts to entrain air into the beverage. Flow of beverage into the eductor should be kept as smooth as possible to reduce pressure losses. It should be noted that, in the high pressure state, the air eduction mechanism is de-activated. 
     The sealing of the filter  104  onto the spokes  153  and the welding of the rim  151  with the outer member  102  ensures that there are no short-circuits and all the beverage has to pass through the filter  104 . 
       FIG. 30  shows a second embodiment of beverage cartridge  100  which can be used in the beverage preparation machine  10  of the present invention. Like components between the first and second embodiments have been referenced with like numerals. Many of the components and functions of the second embodiment of cartridge  100  are the same as for the first embodiment. However, it can be seen from  FIG. 30  that the cartridge  100  has a greater overall height compared to the cartridge  100  shown in  FIG. 29 . The outer member  102  is taller and thereby defines a larger void space in which a larger quantity of beverage ingredients  200  can be stored. The second embodiment of cartridge  100  is therefore suitable for dispensing larger volumes of beverage. The diameter of the outer member  102  and cartridge  100  are the same as in the first embodiment. Typically the storage volume of the cartridge  100  when assembled is 50 to 58 ml±20%. As with the first embodiment, the upper surface of the outer member  102  is provided with a recess having a clamping surface  118  located at a bottom thereof. According to the present invention, the separation D between surface  118   a  and the underside of the laminate  105  is the same as for the first embodiment. As a result, the elongated recess extends approximately 60% of the distance towards the laminate  105 . This advantageously allows for a simplified clamping arrangement to be used as described below. 
     Also, the second embodiment of cartridge  100  lacks an eductor air inlet  171 . 
     The first and second embodiments of cartridge  1  described above are given as examples of an “eductor” type of cartridge and a “non-eductor” type cartridge which may be used with the improved beverage preparation machine described above.