Abstract:
A beverage preparation machine of the type which uses pre-packed cartridges of beverage ingredients. The cartridges may be designed so that air becomes entrained so as to produce a desired foam or crema. Air inlets are provided in an outlet nozzle to allow air to enter the beverage preparation machine and so be available for entrainment. Advantageously, the air inlets extend through the sides of the nozzle in an elevated position at a widened portion of the nozzle. This reduces the flow of beverage into and through the air inlets, aiding cleanliness.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. national phase application of International Application No. PCT/GB2010/002094, filed Nov. 12, 2010, which claims benefit from Great Britain Application No. 0919852.4, filed Nov. 12, 2011, both of which are hereby incorporated herein 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. 
     SUMMARY 
     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. Air is entrained into the beverage as it is being brewed to produce the desired 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 that use such cartridges require far less cleaning and can enable the user to make a selection of beverages. 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 cartridge to form the extracted solution. The cartridge may be designed so that air becomes entrained so as to produce a desired foam or crema. Air inlets are provided to allow air to enter the beverage preparation machine and so be available for entrainment within the cartridge. For example, the outlet nozzle of the machine may include an air inlet passage to allow air to pass up into the machine and through to the cartridge where it may become entrained in the flow of beverage being dispensed to assist in forming the desired foam or crema. The use of cartridges in domestic coffee 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 cartridges is described in EP-A-1440644, and examples of cartridges are described in EP-A-1440903. 
     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. 
     Accordingly, the present invention provides a beverage preparation machine configured to dispense a beverage through an outlet nozzle. The outlet nozzle has one or more sides that define a conduit between an entrance and an exit. The conduit widens downstream of the entrance to form a wider portion. Beverage may pour down the conduit before exiting the outlet nozzle and hence the beverage preparation machine. The outlet nozzle further comprises one or more air passages that extend through the one or more sides of the nozzle to provide fluid communication between the conduit and atmosphere. This allows air to be drawn into the beverage preparation machine as a beverage is dispensed. This allows air to flow into the beverage machine to replace air exiting the beverage machine with the beverage. For example, for all beverages including those like tea that do not have a foam, air is drawn downwards with the flow of beverage through the outlet nozzle. For beverages with a foam, air is also lost from the beverage machine in the air entrained within the beverage. In both cases, the air inlets provide a path for a flow of air to enter the beverage machine and replace the air that is lost. The air may flow into the beverage machine, as required, for example to be drawn into a cartridge where it is entrained into the beverage. Where a beverage does not have a foam, the air passages do not result in an adverse effect: they merely allow air drawn out by the beverage flow to be replaced. 
     At least some of the air passages provided, and preferably all of the air passages provided, are located in an elevated position in the wider portion above the exit of the outlet nozzle. It should be appreciated that in the following description, reference to each of the air passages need not necessarily mean each and every air passage provided in the outlet nozzle but, in its broadest sense, may mean each of a subset of the air passages provided. Thus, the outlet nozzle may comprise one or more air passages in an elevated position and one or more air passages at the exit of the outlet nozzle. 
     Preferably, the one or more air passages are paired, with each pair of air passages facing each other across the conduit. Optionally, the one or more air passages are equally spaced around the outlet nozzle. 
     Providing one or more air passages in elevated positions is advantageous as it lessens the chance of beverage entering the one or more air passages. With no beverage entering the air passages, they will remain cleaner for longer. Thus the need to clean may be avoided or, at the very least, much reduced. As the one or more air passages are provided in the side of the outlet nozzle, and may extend directly through the side, they may be very short which further aids ease of cleaning. 
     This effect of inhibiting beverage flow into the air passages may be optimised in many different ways. For example, greater benefit may be achieved by raising the position of the air passages by a greater degree. For example, each of the one or more air passages may be located adjacent the entrance to the outlet nozzle. Another way of optimising the effect is to try to ensure that the beverage does not flow close to the air passages. This is achieved by widening the conduit and placing each of the one or more air passages in the wider portion of the conduit. Widening the conduit also advantageously provides a head space around the flow of beverage. Thus, the air passages allow air to be drawn into the head space around the beverage. The air passages provided in the conduit do not lead to entrainment of air into the beverage flow within the conduit. As described above, for all beverages, air will be drawn downward with the beverage flow through the conduit although this will lead to little, if any, entrainment. Rather, air flow will be down the head space around the beverage flow. Where entrainment is desired, air flowing in through the air passages may flow up into the beverage preparation machine, for example to a cartridge where the air is entrained into the beverage flow, as described above. Thus, the air inlets do not lead to air entrainment within the outlet nozzle. Instead, the outlet nozzle acts merely to preserve a foam where present, and to preserve the absence of a foam where not present. 
     Widening of the conduit may be achieved by providing a shoulder in the conduit to define a narrower portion and the wider portion. Each of the one of more air passages may be located in the wider portion at the shoulder to shelter them from the flow of beverage. The shoulder may be stepped or it may be curved so as to be gradual. 
     The outlet nozzle may or may not be formed as a single piece. For example, the outlet nozzle may be an assembly of two or more parts. Optionally, the outlet nozzle comprises first and second parts that join together to form the conduit, with the one or more air passages being formed at the joint between the first and second parts. The two parts may be joined in any common way. In a contemplated embodiment, the first part is provided with a downwardly-extending rim and the second part is provided with an upwardly-extending rim, the two rims being sized such that one is received snugly within the other and being provided with interruptions that are aligned to form air passages through the joint. The rims may be used to secure the first and second parts to each other, e.g. using co-operating screw threads. 
     As noted above, the present invention finds useful application in beverage preparation machines that are arranged to prepare beverages from a cartridge containing one or more beverage ingredients. Typically, such cartridges are received in a cartridge holder that may be closed to seal the cartridge within the machine such that fluid like water can be passed through the cartridge to prepare the beverage. The prepared beverage exits the cartridge and is dispensed through the outlet nozzle of the machine. The machine may further comprise a piercer positioned to pierce the underside of a cartridge when placed in the cartridge holder. Typically, the piercer will pierce a laminate such as a foil provided on the underside of the cartridge. The piercer may have a hollow centre to form an outlet for beverage to exit the cartridge. The entrance to the hollow centre of the piercer may form the entrance to the outlet nozzle, i.e. the piercer may form part of the outlet nozzle. 
     Furthermore, the outlet nozzle may comprise first and second parts that join together to form the conduit. The first part may comprise the piercer on its topside and a downwardly-extending rim on its underside with the hollow centre of the piercer extending from the piercer to end within the rim such that the rim encircles the hole through the first part. The second part may comprise an upwardly-extending rim. Preferably, the two rims are sized such that one is received snugly within the other and are provided with interruptions that are aligned to form air passages through the joint. The hole may extend through the first part to terminate centrally within the downwardly-extending rim. This rim may be set back from the hole to form a shoulder in the conduit through the outlet nozzle. Where the upwardly-extending rim of the second part is received within the downwardly-projecting rim, the internal diameter of the upwardly-projecting rim may be such that it is spaced back from the hole so as to form a shoulder. The hole through the first part may become wider as it passes from the topside to the underside, for example by forming its side wall to curve. The curvature may see the side wall smoothly transition into the underside of the first part. The downwardly-projecting rim may extend from or adjacent to the region where the side wall transitions into the underside. 
     The present invention also provides a method of preparing beverages using a beverage preparation machine according to any of the preceding paragraphs. The method may comprise causing the machine to dispense a beverage through the outlet nozzle such that substantially no beverage flows through the one or more air passages. Where the beverage preparation machine is adapted to prepare beverages from a cartridge containing one or more beverage ingredients, the method may further comprise placing such a cartridge into a cartridge holder of the beverage preparation machine, causing the machine to prepare a beverage from the cartridge and to dispense the beverage so prepared through the outlet nozzle such that substantially no beverage flows through the one or more air passages. 
     Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         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 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. 8  is a perspective view of a piercer plate according to an embodiment of the present invention shown in an inverted position; 
         FIG. 9  is a cross-sectional side elevation of the piercer plate of  FIG. 8  shown in its correct orientation; 
         FIG. 10  is a perspective view of a nozzle piece according to an embodiment of the preset invention; 
         FIG. 11  is a cross-sectional side elevation of the nozzle piece of  FIG. 10 ; and 
         FIG. 12  is a cross-sectional side elevation of the piercer plate of  FIG. 8  and the nozzle piece of  FIG. 10  when assembled. 
     
    
    
     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. The beverage machine may comprise a soda fountain, beer pump, or the like. The present invention enjoys particular benefit when used with beverage preparation machines for preparing hot beverages like coffee, tea, hot chocolate and hot milk. In particular, the improvements provided by the present invention enable the production of good quality espressos with a high-quality crema, yet provide a design that is easy to keep clean and hygienic, and that is capable of providing other high-quality beverages. 
     The improvements will be described with reference to a known beverage preparation machine  10  that 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 which may or may not be 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 pump  14 , 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  19  and cartridge recognition means  20 . The cartridge head  17  further comprises inlet and outlet piercers  21 , 22  for forming in the beverage cartridge  19 , in use, an inlet for liquid to enter the cartridge  19  and an outlet for the prepared beverage to exit the beverage cartridge  19 . Beverage leaving the cartridge  19  through the outlet exits the machine  10  from a nozzle piece  70 . 
     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. 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 from the nozzle piece  70 . The dispensing station  27  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 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 pump  14  is operatively connected between the tank  12  and the water heater  13 , and is controlled by the control processor. The flow rate of water through the machine  10  can be controlled by the control processor. A volumetric flow sensor (not shown) is preferably provided in the flow line either upstream or downstream of the pump  14 . 
     The heater  13  is located in the interior of the housing  11 . The water for the dispense cycle is delivered to the cartridge head  17  at a predetermined temperature. The heater  13  is able to adjust quickly the delivery temperature to the required temperature, generally between 80° C. and 98° C., and possibly higher from the incoming water temperature. The heater  13  comprises an over-temperature cut-off which shuts off the heater  13  if the temperature exceeds 98° C. Where desired, the machine  10  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 heater (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  19  by means of a valve. If the pressure of the water flow is acceptable, the water is passed to the cartridge  19 . 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 that 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  19 . 
     The cartridge holder  18  is designed to be capable of handling the opening forces generated by the pressure inside the cartridges  19 , which is around 250 kg for espresso beverages. During operation of the machine  10  the cartridges  19  attempt to expand, but the integrity of the cartridges  19  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 cartridge mount  45  is provided with a substantially circular recess  55  which receives in use the beverage cartridge  19 . The recess  55  includes an irregularity  56  for accommodating a handle portion of the beverage cartridge  19  which also acts to prevent rotation of the beverage cartridge  19  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 . The cartridge mount  45  then moves 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  19  during a dispense cycle and can also confirm visually whether a cartridge  19  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  17  when in the closed position as shown in  FIG. 6 . When the cartridge 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  19   a  of the beverage cartridge  19  biasing it against the lower part  44  as shown in  FIG. 6  (in which the arrangement is illustrated containing a cartridge  19  having a greater depth). The pressure exerted by the tubular extension  61  ensures a fluid tight seal between the cartridge  19  and the holder  18 . 
     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 having a sharpened end for perforating a laminate of the beverage cartridge  19  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. 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  19 . The remainder of the upper end is cut back longitudinally of the cylinder at least to the base of the teeth of the serrated portion, as shown at  68 , to fold or pull the cut laminate away from the outlet aperture before the beverage is dispensed there through. 
     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. Preferably, the inlet piercer  21  and the outlet piercer  22  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 . To close the upper part  44 , a user takes hold of it 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  19   a  of the beverage cartridge  19 . Continued rotation of the upper part  44  rotates the upper part  44  and cartridge mount  45  down into contact with the lower part  43 . 
     With the upper part  44  closed, the piercer  22  has formed the outlet through the laminate provided in the cartridge  19 . The outlet piercer  22  has a hollow centre  22   a  that extends downwardly through the fixed lower part  43  to communicate with the internal bore  71  of the nozzle piece  70 . As can be seen best in  FIGS. 6 and 7 , a conduit extends from the outlet piercer  22  to the base of the nozzle piece  70 . The nozzle piece  70  is provided with a central dispensing passage  72  and a peripheral air inlet passage  73 . The entrance to the central dispensing passage  72  is positioned directly beneath the centre of the outlet piercer  22  such that beverage flowing from the cartridge  19  falls through the central dispensing passage  72  and out of the nozzle piece  70 . 
     The air inlet passage  73  extends from the base of the nozzle piece  70  to the top of the nozzle piece  70  where it meets the base of the outlet piercer  22 . Thus, air may be drawn up and to the cartridge  19 . The cartridge  19  may be designed to cause air to become entrained in the flow of beverage as it exits the cartridge  19 . For example, the cartridge  19  may include a venturi passage or other feature that causes air to become entrained in the flow of beverage. In this case, the air inlet passage  73  allows the air to be drawn up to the cartridge  19  for entrainment. Where a foam is not desired, the cartridge  19  is designed such that air is not entrained. For example, the cartridge  19  may lack an inlet that is otherwise required to admit an air flow provided by the air inlet passage  73 . Further details of such cartridge designs can be found in EP-A-1440903. 
     While the airflow is important in forming the desired crema in drinks like espresso coffee, and foams in other beverages such as hot chocolate or milk, in practice it has been found that beverage may also flow down the air inlet passage  73  and then from the nozzle piece  70 . This flow of beverage has several disadvantages. The flow of beverage impedes the flow of air up the air inlet passage  73  to the detriment of the quality of the crema produced. Also, the flow of beverage down the air inlet passage  73  necessitates that the passage  73  be cleaned regularly, an operation that is hampered by the fact that the air inlet passage  73  is generally much smaller than the central dispensing passage  72 . 
     Control of the brew cycle is effected by the control processor of the beverage preparation machine  10 , the central processor comprising 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  19  during the operating stage, the speed of charging the beverage cartridge  19 , 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  19  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  19  comprises a code provided on or in the cartridge  19  representing the operational parameters required for optimal dispensation of the beverage in that cartridge  19 . 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  19 . This is especially advantageous where two or more beverage cartridges  19  are used sequentially to form a beverage. For example a coffee cartridge may be used 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  19  into the cartridge head  17 , carrying out a dispense cycle in which the beverage is dispensed, and removal of the cartridge  19  from the machine. 
     To insert the cartridge  19 , the cartridge holder  18  is opened as described above to expose the cartridge mount  45 . The cartridge  19  is then placed on the cartridge mount  45  received within the recess  46 . The cartridge holder  18  is then closed as described above. During closure the inlet and outlet piercers  21 , 22  pierce the cartridge  19  to form the cartridge inlet and outlet. 
     To commence the dispense 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. Once the barcode 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  19  is charged with liquid from the storage tank  12  by means of the pump  14 . The charging with water causes the beverage ingredients in the cartridge 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  19  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  19  is selected to ensure that liquid or beverage does not drip out of the cartridge outlet during this stage. 
     The pause stage allows the beverage ingredients 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 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 dispense stage, liquid is passed through the cartridge  19  in order to produce the beverage from the beverage ingredients. 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 beverage cartridge  19 . Brewing and/or mixing of the beverage in the beverage cartridge  19  occurs, as described in EP-A-1440644, before the prepared beverage exits the cartridge outlet, optionally entrains air into the beverage flow from the air flow provided by air inlet passage  73 , flows through the central dispensing passage  72  of the nozzle piece  70  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 the pressurised steam is blown through the beverage preparation machine  10  and the beverage cartridge  19 . 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  19  by opening the cartridge holder  18  and manually removing and disposing of the cartridge  19 . Alternatively, the machine  10  may be provided with an automatic ejection mechanism for removing the cartridge automatically on opening the cartridge holder  18 . 
     An embodiment of the present invention is shown in  FIGS. 8 to 12 . An outlet nozzle assembly  100  is shown that comprises a piercer plate  110  and an nozzle piece  120 , broadly corresponding to those shown in  FIGS. 5 and 6 . However, the outlet nozzle assembly  100  is advantageously modified to provide an improved air inlet. 
     The piercer plate  110  provides an inlet piercer  111  and an outlet piercer  112  on its topside. The piercers  111 , 112  are akin to the piercers  21 , 22  described previously. Thus the outlet piercer  112  may penetrate a laminate provided in a cartridge  19  to form an outlet. The outlet piercer  112  has a hollow centre  113  that extends through the piercer plate  110  from topside  115  to the underside  116 . The outlet piercer  112  surrounds the hollow centre  113  on the topside  115 , and is surrounded by a skirt  114  on the underside  116 . The hole  113  forming the hollow centre increases in size from topside  115  to underside  116  and in fact curves smoothly such that the internal wall  117  of the hole  113  blends smoothly into the underside  116  of the piercer plate  110 , save for the skirt  114 . The skirt  114  is provided with four interruptions  118 , equally spaced around the skirt  114  at ninety degree intervals. 
     The nozzle piece  120  is generally cylindrical with a hollow centre  121 . The top of the nozzle piece  120  is provided with a brim  122  from which a collar  123  extends. The collar  123  is sized to received the skirt  114  of the piercer plate  110 . The piercer plate  110  and nozzle piece  120  may be secured to one another in any convenient fashion, e.g. a snap-fit, a bayonet fitting, screw thread, etc. When joined, the hollow centre  113  of the piercer plate  110  and the hollow centre  121  of the nozzle piece  120  form a passage through which the exiting beverage flows. This passage widens, thereby forming a head space around the flow of beverage exiting the beverage machine  10 . 
     The collar  123  of the nozzle piece  120  is provided with four gaps  124  of a corresponding size to the interruptions  118  provided in the skirt  114  of the piercer plate  110 . The gaps  124  are also equally spaced around the collar  123  at ninety degree intervals. When assembled, the interruptions  118  in the skirt  114  are aligned with the gaps  124  in the collar  123 . The piercer plate  110  and/or the nozzle piece  120  may have indexing means to ensure that the interruptions  118  and gaps  124  align when the outlet nozzle assembly  100  is assembled. When aligned in this way, the interruptions  118  and gaps  124  form air passages  102  between the central bore  104  of the outlet nozzle assembly  100  and atmosphere. The air passages  102  are formed in the widened portion of the passage, thereby admitting air into the head space around the flow of beverage. 
     The air passages  102  extend from atmosphere just under the fixed lower part  44  of the cartridge head  18 , and allow air to be drawn into the nozzle piece  120 . Where air is being entrained in the beverage being dispensed, air entering through the air passage  102  may be drawn up into the beverage machine  10  to the cartridge  19  where it is available for entrainment into the beverage being dispensed from the cartridge  19  through the outlet nozzle assembly  100 . This airflow may assist in the formation of a crema or other foam, as described above. 
     In addition to providing an air flow to replace air being entrained in the beverage as it exits the cartridge  19 , the air passages  102  allow an airflow into the nozzle piece  120  to replace air drawn down through the nozzle piece  120  by the flow of beverage. This air flow is present even when dispensing beverages such as tea where air entrainment into the beverage is to be avoided. Thus, positioning the air passages  102  in the head space around the beverage flow as it does not lead to entrainment of air into the beverage flow within the nozzle piece  120 . Yet, where entrainment is required, an air flow into the beverage machine  10  is provided that may continue to the cartridge  19  where the air is entrained into the beverage flow. 
     Moreover, the passages  102  formed by the interruptions  118  and gaps  124  are formed at the top of the nozzle piece  120  such that flow of beverage into the air passages  102  is minimised. This is further aided by the widening of the hole  113  through the piercer plate  110  from the outlet piercer  112  to where it meets the nozzle piece  120 . As beverage does not flow through the air passages  102 , they will stay clean for far longer. In addition, cleaning the air passages  102  is straightforward. The piercer plate  110  need only be removed from the fixed lower part  44  and, optionally, the nozzle piece  120  may be removed from the piercer plate  110 , and then the interruptions  118  and the gaps  124  are easily cleaned. This is to be contrasted with the narrow elongate air inlet passage  73  of  FIGS. 6 and 7 . 
     Moreover, adopting the arrangement of  FIGS. 6 and 7  by removing the air inlet passage  73  from within the nozzle piece  70  enlarges the passage through the nozzle piece  70 . 
     It will be evident to the person skilled in the art that modifications may be made to the embodiment described above without departing from the scope of the invention as defined by the appended claims. 
     For example, the number of air passages  102  formed through the outlet nozzle assembly  100  may be varied from the four shown in  FIGS. 8 to 12 . For example more or less may be used. The size and positioning of the air passages  102  may also be varied, and the sizes of the interruptions  118  and gaps  124  need not be the same. Preferably, an even number of air passages  102  are formed as pairs that are aligned across the skirt  114  and collar  123 . 
     The size of the skirt  114  and the collar  123  may also be varied. Moreover, the sizes of the skirt  114  and collar  123  may be varied, or may be reversed such that the collar  13  of the nozzle piece  120  is received within the skirt  114  provided on the underside of the piercer plate  110 . 
     There may not be a requirement for an outlet piercer  112 . For example, the present invention may be used with coffee percolators that dispense brewed coffee through a filter funnel into the outlet nozzle assembly  100 . Indeed, the present invention may be used with many types of beverage preparation machines, including those that merely hold and dispense a beverage (e.g. soda siphons, beer taps, etc.). Of course, other types of beverage preparation are envisaged, such as brewing coffee and/or tea or heating beverages such as milk. 
     The outlet nozzle assembly  100  may comprise further parts, e.g. devices for ensuring the quality of a foam produced with the beverage. These devices may be provided in the central bore  104 , for example surfaces that provide a flow interruption. Also, the outlet nozzle assembly  100  may comprise a further part that joins downstream of the one or more air passages  102 . For example, this part may include a surface for controlling the foam produced. Thus, the air passages  102  may help form a foam, and further devices in the outlet nozzle assembly  100  may help preserve the foam.