Abstract:
A beverage whipper, including a whipper disk configured for spinning within the whipper and having a radius is disclosed. The whipper disk further includes a front surface and a plurality of forward-facing concave surfaces that divide the front surface into a plurality of front surface sections. The concave surfaces extend generally radially over more than half the radius and have a circumferential width and a depth, wherein the width is larger than the depth. The front surface sections have a total area that is at least 4-times the total area of the concave surfaces. Also, a beverage dispenser that includes the whipper for forming beverages having crema such as espresso or cappuccino.

Description:
This application claims the benefit of application No. 61/003,168 filed Nov. 14, 2007, the entire content of which is expressly incorporated herein by reference thereto. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a mixing device that provides a frothy fluid product. More particularly, the invention relates to a mixing device for mixing, frothing, and dispensing a beverage. 
     BACKGROUND OF THE INVENTION 
     Espresso drinks, in comparison to other coffee drinks, are noted for a fine layer of bubbles (“crema”) that settles on the top of the drink from fine bubbles that are interspersed within the drink during the brewing process. Coffee consumers in many markets view a crema as a key indicator of a good cup of espresso. Espresso and other coffee and milk drinks are sometimes prepared by mixing a powder or fluid concentrate in water. However, the quality perception of theses drinks is sometimes an issue if the crema does not resemble that when the espresso is prepared from ground coffee. 
     Mixing devices are known for speedier preparation of coffee, espresso, and other such beverages and other foods by mixing a powdered or liquid concentrate food component with a liquid, such as water. These devices typically feed the powdered or concentrate component into the water, which is often pumped tangentially into a mixing chamber to create a whirlpool to mix the powder or concentrate into the water. When these products are reconstituted in a dispenser, the process does not follow the same steps as a roast and ground espresso product so a fine layer crema is not generated. Instead, a layer of undesirable large bubbles (“foam”) may be generated, the magnitude dependent on the particular recipe of the powder or concentrate and the flow path for dispensing. To the consumer these bubbles could indicate that the coffee was not made correctly. 
     In known mixing devices, the mixture is then fed to a whipping mechanism, which is usually a rotating plate. The plate aerates the mixture and produces a froth. The frothed mixture is usually dispensed into a container for drinking. Such known whipping mechanisms, however, may only increase the amount of foam present in the coffee because the froth that they produce is aimed at producing bubbles that are much larger than those that distinguish crema. 
     U.S. Pat. No. 5,927,553, for example, discloses a mixing and dispensing apparatus with a cruciform frothing blade. Other shapes of frothing blades are also known. For instance, companies such as Rhea and Zanussi use whippers with an axially short disk with very steep sloped walls. U.S. Pat. No. 7,059,498, for example, discusses a mixing device including a conical whipping rotor that is configured to produce large bubbles within a beverage so as to form a layer of foam along the top of the beverage. Other whippers have disks with independent ramps extending from a substantially flat plate. The known devices generally have their greatest efficiency for preparing a small group of products. 
     Therefore, there is a need for a mixing device with an improved whipping mechanism that reduces or eliminates the production of large bubbles or foam in favor of finer bubbles. 
     Furthermore, crema generation is often benefited by slow flow speeds, whereas when filling a carafe with a large amount of “American style” coffee, speed is favored and crema production may not even be desirable. If dispensed into a multi-cup carafe for a server to pour from, the large bubbles can often prevent full filling of the carafe if they are overflowing from the top. For this solution, a system is needed that does not produce bubbles or crema and is able to rapidly fill a carafe. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present invention relates to a beverage whipper. The beverage whipper includes a whipper disk having a configuration for whipping a beverage mixture to produce a high quality crema. The configuration is such that the whipper disk defines a transverse radius and includes a front surface and a plurality of forward-facing concave surfaces that divide the front surface into a plurality of front surface sections. The concave surfaces extend generally radially over more than half the radius and having a circumferential width and a depth. The width is larger than the depth, and the front surface has an area that is at least 4-times the area of the concave surfaces. 
     Preferably, the whipper disk includes a relatively sharp transition between the front surface and the concave portions for promoting cavitation when the whipper is spinning. The relatively sharp transition is preferably disposed on both circumferential sides of each of the concave surfaces. 
     In a preferred embodiment, the concave surfaces are substantially semi-cylindrical. Further preferably, the front surface is domed in a convex direction and can be formed having a generally elliptical cross-section. The front surface preferably has a radially inner portion and an outer edge, the concave portion extending substantially from the inner portion to the outer edge and preferably having a width-to-depth ratio of at least about 1.5 at any point along the concave surface. 
     Another embodiment of the present invention relates to a beverage dispenser. The beverage dispenser can also include a whipper housing defining a cavity configured for flowing a liquid beverage mixture therethrough, the whipper disk being rotatably disposed within the housing cavity. A motor is operably associated with the whipper to spin the whipper disk sufficiently fast to produce a high quality crema in the beverage mixture. An outlet conduit is connected downstream to the housing for dispensing the whipped beverage mixture. The dispenser also includes a restrictor associated with the outlet conduit for restricting the flow of the whipped beverage mixture therethrough. 
     According to a first mode, the restrictor is preferably configured for prolonging a dwell time in which the beverage mixture is acted on by the whipper disk. In an embodiment, a fluid-flow restrictor is disposed between the housing and the fluid outlet, and is configured to increase fluid back-pressure within the housing for prolonging the dwell time in which the beverage mixture is acted on by the whipper disk. The preferred restrictor is a mean to restrict the diameter of the outlet conduit. In the preferred embodiment, the restrictor can be a tapered portion of the outlet conduit. Tapered portion is configured to restrict the flow of the fluid therethrough, which can reduce the velocity of the flow of the liquid product through output conduit, which, in turn, prolongs the exposure of the fluid to the whipper disk. This can lead to increased efficiency in the production of crema-forming bubbles. Usually it is preferable that the tapered portion extends over a long length of the outlet conduit rather than on a short length. 
     According to a second mode, the restrictor can be configured for breaking up bubbles of the crema larger than a predetermined size within the fluid, thereby reducing the number of bubbles present within the fluid over the predetermined size. The restrictor can be in the form of a spiral restrictor disposed within the outlet for disrupting the reducing larger bubbles in the crema. Alternatively, the restrictor can define a plurality of holes having diameter and a length along a direction of flow that is at least as long the diameter for reducing larger bubbles of the crema. 
     The beverage dispenser can be implemented according either the first or the second above mode, yet in the preferred embodiment the beverage dispenser implements simultaneously the first and the second mode. According to this preferred mode, the beverage dispenser comprises at least two types of restrictor: one first restrictor configured to increase fluid back-pressure within the housing for prolonging the dwell time in which the beverage mixture is acted on by the whipper disk and a second restrictor configured for breaking up bubbles of the crema larger than a predetermined size within the fluid. Said first restrictor is usually placed upstream the said second restrictor. 
     The beverage dispenser can also include a bypass inlet in fluid communication with the outlet conduit and configured for receiving a fluid from a fluid source that feeds both the mixing chamber and the bypass inlet. In this embodiment, the beverage mixture is preferably formed at a first concentration that is variable based on a volume of fluid provided into the mixing chamber, and the outlet conduit is configured to reduce the first concentration to a lower, second concentration by receiving the fluid from the fluid source through the bypass inlet while the beverage mixture passes therethrough. 
     A further embodiment of the invention relates to a method of preparing a beverage mixture with a layer of high-quality crema. The method includes the step of introducing a beverage mixture into a housing including a whipper disk rotatably disposed within the housing and configured for whipping a beverage mixture to produce a high-quality crema. The method further includes causing the whipper disk to spin sufficiently fast to produce a high-quality crema in the beverage mixture, and dispensing the whipped beverage mixture through an outlet conduit connected downstream to the housing, the outlet conduit including a restrictor for restricting the flow of the whipped beverage mixture through the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above features and other advantages of the invention will become better understood by reference to the following detailed description of preferred embodiments and the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a whipping mechanism according to an embodiment of the present invention; 
         FIG. 2  is a side cross-sectional view thereof; 
         FIG. 3  is a top cross-sectional view thereof; 
         FIG. 4  is a perspective view of a whipper disk used therein; 
         FIG. 5  is a perspective view of a plate that can be affixed on an output nozzle thereof; and 
         FIG. 6  shows an alternative embodiment of a dispensing spout configured for use with the whipping mechanism of  FIGS. 1-5 , the dispensing spout including a removable sieve. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1-3 , a preferred embodiment of the invention includes a mixing device  10  that has an input container  12 . The input container  12  comprises a bowl portion  14  with a tangential inlet  16  for feeding a fluid under pressure. An automatically controlled valve is preferably provided to control the fluid flow into the input container  12 . The fluid is introduced through the tangential inlet  16  at a speed selected to produce a swirling flow, preferably substantially a whirlpool effect. 
     A component to be mixed with the fluid, which may be a liquid concentrate or a powdered food substance, is fed into an inlet  18  or into a plurality of inlets, which are generally configured as an opening at the cover portion  20  above the bowl portion  14 . Preferably, the component is in the form of a liquid concentrate. The concentrate or other substance can be fed by hand or automatically by a source that is disposed above the cover  20  of the device  10 . The source preferably has a dosing mechanism, such as a dosing screw, to automatically dose a predetermined amount of the food substance into the input container  12 . A cover  20  extends around the inlet  18  or inlets and includes a lip  19 , protruding into the bowl portion  14  to prevent the swirling fluid from exiting the input container  12  by the upper side thereof. A suction is applied to orifice  21 , adjacent the underside of the lip  19  for extracting any splashed fluid material. The inlet  18  is sufficiently large to receive the substance poured therein and also to receive a sufficient amount of air for mixing with the fluid and component. 
     In the embodiment shown, a throat portion  22  of the input container  12  is disposed below the bowl portion  14 . The throat portion  22  preferably has a narrower diameter than the bowl portion  14  and has a throat opening  24  disposed on a lateral side, as shown in  FIG. 2 . The throat portion  22  is preferably generally coaxial with the bowl portion  14  and narrows substantially evenly along the axis of the bowl portion  14 . This improves the fluid flow therein and reduces any trapping of powder or other food substance. Preferably, a transition between the bowl portion  14  and the throat portion  22  has an inward bend  25 , followed by a conically sloped portion  27 , which is followed by an outward bend  29 , in cross-section. 
     Referring to  FIGS. 2 and 3 , a whipper assembly  26  is in fluid communication with the input container, preferably at the throat opening. The whipper assembly includes a whipper disk  28 . A motor  30  drives disk shaft  32 , which drives the whipper disk  28  so that the motor  30  drives the whipper at about whipper axis  34 . A motor controller is preferably provided to control the operation and speed of the motor  30 . 
     The preferred whipper disk  28  has a convex, substantially dome-shaped whipper surface  36 . The dome-shaped surface  36  preferably faces outwardly with respect to the whipper axis  34 . The dome shape of whipper surface  36  can be configured such that whipper surface  36  is a revolved surface formed from a circular arc segment. In such a configuration, whipper surface  36  is in the form of a truncated sphere having a transverse radius  38  and a surface radius  48 . Preferably, transverse radius is between 5 mm and 20 mm in length. In an embodiment, transverse radius is at least about 12 mm. Preferably, transverse radius  38  is between 10 mm and 18 mm and more preferably about 16 mm. Surface radius  48  is larger than transverse radius, and is preferably between 3 times and 5 times larger than transverse radius. In a preferred embodiment, surface radius  48  is about 4 times larger than transverse radius  38 . In an embodiment surface radius is at least about 20 mm. In one embodiment, surface radius  48  is preferably less than about 100 mm. In a preferred embodiment, surface radius  48  is between about 30 mm and 80 mm and is more preferably about 65 mm. Alternatively, whipper surface  36  can be a surface of revolution formed by a portion of an ellipse or other oval shape. In such an embodiment the segment of the ellipse used to form the surface of revolution is symmetrical about the minor axis thereof. The whipper surface  36  preferably has a surface area of between about 150 mm 2  and 3000 mm 2 . In a preferred embodiment, whipper surface  36  has a surface area of between about 500 mm 2  and 1500 mm 2 , and more preferably between about 700 mm 2  and 900 mm 2 . 
     A central tube  42  is formed substantially near the center of whipper disk  28  along whipper axis  34 . Whipper surface  36  surrounds central tube  42  and is configured to have a surface area that is between 4.5 and 5 times the transverse area of central tube  42 . More preferably the surface area of whipper surface  36  is about 4.8 times the transverse area of central tube. Preferably, a line  68  passing from the edge of whipper disk to the intersection of whipper surface  36  and central tube  42  forms an angle  69  relative to a plane defined by the edge of whipper disk. Angle  69  can vary with the diameter and height of whipper disk, and is preferably between about 0° and about 45°. Preferably, angle  69  is between 10° and 30°. More preferably angle  69  is about 15°. Preferably, whipper disk has a height  44  that is defined as the distance between a plane formed by the outside edge of disc back surface  49  and a plane defined by the intersection of whipper surface  36  and central tube  42 . Preferably, height  44  is at least about 1 mm and at most about 15 mm, more preferably is at least about 2 mm and at most about 8 mm, although other heights can be used. In an embodiment, height  44  is between 4 mm and 8 mm, and more preferably about 5 mm. 
     Whipper disk  28  includes a plurality of concave portions  60  formed thereon. That separate whipper surface  36  into segments  39 . Concave portions  60  preferably extend from the center of whipper disk  28  radially outward to near the edge of whipper disk  28 . In the embodiment shown, concave portions  60  have a uniform shape with respect to whipper surface  36 , and the depth is not uniform, decreasing in a radial, outward direction. In an alternative embodiment, the shape and depth can be varied or uniform. In a preferred embodiment, the width  66  and depth  67  are measured at the innermost portion thereof, as shown in  FIG. 4 . In an embodiment, width  66  is between about 1 and 2 times larger than the depth  67 . More preferably the width  66  is about 1.5 times larger than the depth  67 . Preferably, each concave portion  60  extends along at least 50% of the radius of whipper disk  28 . In the embodiment shown in  FIG. 4 , the innermost end of concave portion  60  is spaced apart from whipper axis  34  in a radial direction. Additionally, concave portion  60  terminates radially inward of the outside edge of whipper disk  28 . In such an embodiment concave portion  60  can extend along at least about 75% of transverse radius  38 . In other embodiments concave portion  60  can extend along at least 80% of transverse radius  38  and more preferably at least 90%. In an embodiment, concave portions  60  may be formed so as to extend substantially all the way to the outside edge of whipper disk  28 . 
     Whipper disk  28  can include a number of concave portions  60 , and preferably includes between 1 and 10 concave portions  60 . In a preferred embodiment, whipper disk  28  includes between 2 and 6 concave portions, and more preferably includes 4 concave portions. The size, and particularly the width  66  of concave portions  60  varies with the number of concave portions  60  present in whipper disk  28  such that the aggregate surface area of whipper surface segments  39  is about three-times the aggregate surface are of the area occupied by concave portions  60 , and more particularly about four times the aggregate surface area. Also, the preferred concave portions  60  are substantially equally spaced about the whipper surface  36 . 
     In a preferred embodiment, concave portions  60  are semicylindrical in shape. In such an embodiment, concave portions  60  extend along an axis  62  and have a radius  63  such that the concave portion is defined by the intersection of the cylinder defined thereby and whipper disk  28 . Accordingly, the size and shape of concave portion  60  will vary with the radius thereof, as well as the position and orientation of axis relative to whipper disk  28 . In a preferred embodiment, axis  62  is normal to whipper axis  34 . In such an embodiment, as with other possible embodiments, concave portions  60  will have a shape that tapers in the outward direction of radius  63 . As shown in  FIG. 4 , the width at the top of concave portions  60  decreases with the distance from whipper axis  34 . Alternatively, axis  62  can be downwardly declined relative to whipper axis  34 . Preferably whipper disk  28  is spaced apart from back wall  58  of the whipper housing at a distance substantially equal to the height  44  of whipper disk  28 , although it can be slightly less by about 5 to 15% in order to give the desired size properties for concave portion. Preferably, radius  63  is between about 1 mm and 10 mm. More preferably, radius  63  is between about 3 mm and 8 mm. In a preferred embodiment radius  63  is about 4 mm. In an embodiment, radius  63  is at least about 1 mm less than the height of whipper disk  28  at the apex of whipper surface  36 . In an embodiment where concave portions  60  taper, the percentage of the overall circumference of whipper surface  36  that is occupied by the concave portions  60  in aggregate can vary with the radial distance from the whipper axis  34  at which the circumference is measured. In an embodiment, at the innermost end of concave portions  60 , concave portions  60  can occupy at least about 50% of the total circumference, and more preferably about 75%. Further, at the outside edge of whipper disk  28 , concave portions  60  can occupy between about 0% and 10% of the total circumference. In one embodiment, concave portions  60  can occupy 0% of the total circumference at a distance of up to 5 mm from the outside edge of whipper disk  26 . In an embodiment, concave portions  60  occupy about 50% of the total circumference at a radial distance that is between about 25% and 50% of the transverse radius  38 . Further, concave portions can occupy less than 25% of the total circumference beginning at a radial distance that is at least about 50% of the transverse radius  38 , and less than about 10% of the total circumference at a distance that is at least about 75% of the transverse radius  38 . 
     The edge  64  formed between whipper surface  38  and concave portion  60  is preferably substantially sharp so as to create cavitations in the fluid exposed thereto. Preferably, an angle  65  is formed along edge  64  that may vary with the distance from whipper axis  34 . Preferably, angle  65 , when measured near the innermost portion of concave portion  60 , is between about 30° and 90° and is more preferably about 90°. In a preferred embodiment, angle  65  preferably decreases as it extends toward the outer edge of whipper disk  26 . Whipper discs with the desirable aspects create small bubbles using a localized vacuum effect as concave cross section of the disc passes through the mixture. 
     The preferred whipper disk  28  is optimized to efficiently produce a quantity of bubbles within fluid based on the flow of fluid substantially near whipper disk  28  at a sufficient flow rate. The formation of bubbles within the fluid is improved by the controlled cavitation within the fluid caused by movement of whipper disk  28  in a volume of fluid surrounding whipper disk  28 . The structure of the preferred whipper disk  28  is configured, according to the embodiments disclosed herein, to produce not only a desired quantity of bubbles within the fluid, but also bubbles that are generally of a smaller size than other known whipping devices. Specifically, when whipper disk  28  is used with a coffee product, and in particular an espresso product formed within mixing chamber  12  as discussed above, the bubbles formed are of a small size sufficient to form a layer of crema when the bubbles settle along the top of the dispensed fluid. Although bubbles within crema and within foam may include some bubbles of a similar size, the bubbles are generally much smaller within crema than within foam. In general, the preferred whipper disk  28  is configured to increase the proportion of small bubbles to large bubbles within the dispensed fluid. 
     Whipper disk  28  preferably includes an attachment portion near whipper axis  34 . Attachment portion is preferably in the form of a central tube  42  that is configured to engage the output shaft of motor  30 . The engagement between tube  42  and the output shaft can be facilitated by a configuration that results in a press-fit therebetween. Preferably the parts are configured to maintain a friction fit therebetween such that whipper disk  28  rotates with the rotation of the motor output shaft  32 . Alternatively, the tube  42  and the output shaft  32  can have mating profiles to facilitate the mutual rotation thereof. Whipper disk  28  is disposed within a whipper housing  52 , which in the embodiment shown is integral part of unitary construction with the input container  12 . 
     The preferred whipper housing  52  has an inner housing surface  54  with a shape that at least partially overlies whipper disk  28 . A shear gap  56  is defined between the inner housing surface  54  and the circumferential portion of the whipper surface  36  that can vary as whipper housing  52  extends over whipper disk  28 . Measured at the most narrow point between whipper disk  28  and whipper housing  52 , the shear gap  56  can be at least about 0.5 mm, more preferably at least about 0.8 mm, and most preferably at least 1 mm. Measured at this location, shear gap  56  is preferably at most about 2.5 mm and more preferably at most about 1.5 mm. In the preferred embodiment, however, the size and configuration of the shear gap is not required in the formation of sufficiently small bubbles within the fluid. Rather, the configuration of whipper disk  28 , itself, influences bubble formation, the whipper housing  52  being shaped to provide both for flow of the fluid into contact with whipper disk  28  and retention of the fluid in contact with whipper disk  28 . Preferably, housing  52  is structured such that as much of the fluid as possible is brought into contact with whipper disk  28 . Similarly, whipper housing  52  is further structured such that the fluid remains in substantial contact with the whipper disk  28  long enough to form an acceptable number of bubbles therein. It is understood that when referring to the fluid coming into contact with whipper disk  28 , that direct contact is not required, it is simply enough that the fluid be influenced by the shape and movement of whipper disk  28  to form the desired cavitations therein, resulting in bubbles. 
     Whipper disk  28  can be spaced from back wall  58 . In the preferred embodiment, rear surface  49  of whipper disk  28  is spaced from back wall  58  at a distance that is minimized to prevent too large a quantity of fluid from passing into the space between whipper disk  28  and back wall  58 , but is sufficient to prevent interference by, for example, friction between whipper disk  28  and back wall  58  during operation of whipper disk  28 . Accordingly, the rear surface  49  of whipper disk  28  is spaced apart from back wall  58  by at least about 0.25 mm and at most 2 mm. More preferably the spacing is at least about 0.5 mm, and most preferably at least about 1 mm. 
     The back wall  58  preferably has a larger diameter than that of the whipper disk  28 , preferably at least about 10% to 20% larger. The outer diameter of the back wall  58  of the preferred embodiment is at least about 30 mm and at most about 60 mm, while the diameter of the whipper  28  is typically 20 mm to 36 mm and more preferably about 32 mm. 
     A product exit tube  72  is disposed downstream of the whipper disk  28  and back wall  58  and is disposed to dispense the prepared fluid mixture. The product exit tube  72  is shown as an integral part of unitary construction with the input container  12 . The product exit tube  72  preferably comprises a conduit with a diameter selected according to the final product that is to be dispensed. The preferred product exit tube  72  has an internal diameter of about between 2 mm and 5 mm for embodiments intended to prepare several different milk and coffee beverages. Embodiments intended primarily for coffee preferably have a product exit tube  72  with an internal diameter of about between 1 mm and 3 mm, and in embodiments intended primarily for milk, the internal diameter is preferably from about 4 mm to 8 mm. The diameter of the product exit tube  72  is selected to obtain the desired pumping performance from the whipper disk  28 . Increasing the diameter of the conduit allows a faster flow, while decreasing the diameter provides more back-pressure to retain the fluid mixture in the whipper assembly and input chamber  12  for a longer time. A dispensing spout  75  is preferably attached at the end of the product exit tube  72  for easier dispensing into a cup. 
     As shown in  FIG. 2 , dispensing spout  75  can be configured with a tapered portion  77  therein, which acts as a restrictor. Tapered portion  77  is configured to restrict the flow of the fluid therethrough, which can reduce the velocity of the flow of the liquid product through output spout  72 , which, in turn, prolongs the exposure of the fluid to the whipper disk  28 . This can lead to increased efficiency in the production of crema-forming bubbles. Preferably, the smallest diameter of tapered portion  77  is at most about 95% of the size of the diameter of exit tube  72  and is more preferably between 80% and 90% of the size, and is most preferably about 88%. Furthermore, the effectiveness of tapered portion  77  can be increased by extending tapered portion  77  over a length of at least 2 cm, and more preferably at least about 5 cm. In a preferred embodiment, tapered portion has a length of between 4 cm and 8 cm, and more preferably about 6 cm although other lengths are possible. Preferably tapered portion is configured to restrict the flow of the fluid therethrough compared to prior whipping devices. In an embodiment, tapered portion  77  can be configured to taper further over the length thereof. For example, tapered portion  77  diameter can continuously decrease until near the downstream end of the dispensing spout  75  reaching a most tapered diameter that is at most about 90% of the diameter of exit tube  72 . In one embodiment the downstream end of tapered portion  77  has a diameter that is between about 60% and 80% of the diameter of exit tube  72 , and more preferably between about 65% and 75%. In a preferred embodiment the diameter of the downstream end of tapered portion  77  is about 68% of the diameter of exit tube  72 . An additional or alternative restrictor can be included within dispensing spout  75 , such as a disk having an aperture formed therein that has a diameter that is smaller than that of exit tube  72 . 
     In an embodiment, dispensing spout  75  can include a secondary inlet  86  for accepting a secondary fluid supply. Preferably, the secondary fluid supply originates from a common source as the fluid that enters mixing chamber  12  through inlet  16 , which preferably includes a heater to heat the fluid, which can be water, to a preferred temperature. The presence of inlet  86  can be useful when a large volume of a beverage, particularly coffee, is to be prepared and dispensed in a short amount of time. A preferred embodiment of device  10  can be shaped such that the prepared fluid flows too slowly through whipper housing  54  and exit tube  72  to produce a large volume thereof in a short amount of time. Accordingly, the beverage can be prepared at a higher concentration than is preferred for drinking by providing less fluid, preferably water, through inlet  16 , than would normally be used. This requires a lower volume of fluid to pass through housing  54 . Fluid, preferably water, is then provided through secondary inlet, which passes through the outlet end thereof and into the container. Preferably, the fluid flow through secondary inlet  86  into dispensing spout  75  is at least partially influenced by gravity. Fluid flow through secondary inlet  86  can be done concurrently with the output of the concentrated fluid from whipper housing  54 . The amount of fluid provided through secondary inlet  86  is preferably suitable to provide the desired consumption concentration for the beverage. Preferably, the device is configured to allow a user thereof to select this option. Further, secondary inlet  86  can be used to provide an unprepared fluid, such as water, from the output end of exit tube  72 . In a further preferred embodiment, the speed of whipper disk can be reduced during such beverage preparation and can further be completely stopped. The downstream end of dispensing spout  75  is preferably structured such that a cup or other beverage conveyance can be placed therebeneath to receive the prepared beverage when dispensed from device  10 . Further preferably, the downstream end of dispensing spout  75  is wider than the tapered portion and is further preferably wider than exit tube  72 . 
     As shown in  FIGS. 5 and 6 , an output plate  80  is preferably affixed on the end of dispensing spout  75 . Output plate  80  is preferably structured to control the rate of fluid flow therethrough such that the fluid provided through secondary inlet properly mixes with the beverage mixture that is provided by whipper outlet  72 . Output plate can also further reduce or eliminate the large, undesirable bubbles when a large volume of fluid product is dispensed. The orifices  82  in output plate  80  are sized to be large enough to allow small crema bubbles to pass therethrough undisturbed, but to either break up larger bubbles or to remove them from the dispensed product. The thickness  84  of output plate  80  was can also contribute to velocity reduction and the reduction in presence of large bubbles. Preferably holes  82  are between about 1 and 1.5 mm in diameter and are more preferably about 1.25 mm. The thickness  84  of plate  80  is preferably between about 1 and 1.5 mm and is more preferably about 1.25 mm. In a preferred embodiment the diameter of openings  82  is preferably about equal to the thickness  84  of plate. 
     A coil spring  88  can be fitted within dispensing spout  75 . Coil spring  88  is configured to disrupt the flow of fluid through exit tube  72  such that large bubbles are trapped therein and separated from the fluid or are, alternatively, broken up into smaller bubbles. In an embodiment, coil spring  88  can extend past the intersection of secondary inlet  86  and tapered portion  77 . Coil spring is preferably formed from stainless steel wire, although other suitable materials can be used. The overall diameter of coil spring  88  can be structured so that coil spring  88  fits within exit tube  72  snugly but without causing compression thereof. Alternatively, coil spring  88  can fit loosely within exit tube  72 . Alternative filter structures can be used in place of coil spring  88 . 
     As shown in  FIG. 2 , a seal, such as O-ring  90 , seals the space between the input container  12  and the back wall member  58  and product exit tube  72  area. 
     In use, the fluid is tangentially introduced into the input container  12  through tangential inlet  16 . In the preferred embodiment, the fluid comprises water, and the flow rate is about between 3 mL/sec and 30 mL/sec, more preferably about between 5 mL/sec and 15 mL/sec, and most preferably about between 9 mL/sec and 12 mL/sec. At the time or preferably after the water flow into the input container  12  is commenced, a powdered food component, such as a powdered coffee product and/or powdered milk, is dosed into the water through powder inlet  18 . Alternatively, a fluid concentrate can be used in addition to or instead of a powder. Preferably the powder dosing begins at least about 0.1 sec after the water dosing begins and more preferably at least about 0.3 sec. later, and preferably at most about 3 sec later, and more preferably at most about 1 sec later. Preferably the water is continued to be fed into the input container  12  until the powder dosing is stopped, and preferably at most about 8 sec after the powder dosing ends, and more preferably at most about 3 sec later, and preferably at least about 1 sec later. When a liquid concentrate is used in place of the powder, the same process steps are implemented. 
     The water and powder start getting mixed in the swirling flow within the input container  12 , including the throat portion  22 . The whipper disk  28  is rotated by the motor  30  at a speed sufficient for pumping the mixture towards the product exit tube  72  and for producing the desired foaming and aeration effect. The whipper disk  28  sucks in air for incorporation into the mixture. The speed of the whipper disk  28  is preferably variable to enable a speed selection to deliver the desired amount of energy to the mixture to produce the desired frothing. For obtaining products of certain qualities, the rotation speed of the whipper disk  28  can be varied between two or more speeds during the preparation of a single product. Device  10  is preferably structured to provide a layer of froth, that is similar in thickness and bubble size to that of crema, especially on beverages like coffee or espresso. Device  10 , for example, can provide a high specific energy dissipation to generate a milk froth and a moderately low specific energy dissipation to obtain a high-quality coffee crema in the same unit. The frothed product is then dispensed through the product exit tube  72 . 
     The energy dissipation of the device can be controlled by adjusting the disk speed, and product flow rate, although these quantities are interdependent. An increase in disk speed and a decrease in flow rate will provide a higher energy dissipation. The preferred flow rate is between at least about 5 g/sec and up to about 30 g/sec, and more preferably at least about 8 g/sec and up to about 15 g/sec. The flow-rate of the system can be controlled using one or more of the previously-discussed restrictor devices. In a preferred embodiment, the flow rate is optimized for the desired high quality crema formation and is at most about 10 g/sec, and is preferably less than about 8 g/s. Also, if rpm is increased, noise and cost of the machine will increase as well. 
     The preferred embodiments described above allow a device of compact size, and with a desirable flow rate for preparing individual drinks to be provided without requiring extremely high disk speeds, such as of above about 30,000 rpm. Preferably, the disk speed is at least about 5,000 rpm and at most about 25,000 rpm, more preferably is at least about 10,000 rpm and at most about 15,000 rpm, although other speeds can be used. At these rotation speeds, whipper disk can have a transverse diameter  38  of about 18 mm or greater. Raising and lowering the disk speed can produce different characteristics for the beverage. Further the combination of a frothed beverage produced using the whipper according to different speeds and the addition or not of a non-frothed liquid from bypass inlet  86  can further vary the beverage characteristics. 
     While illustrative embodiments of the invention are disclosed herein, it will be appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. For example, the whipper disk may have an inward facing whipper surface and rotate with respect to a portion of the whipper housing that extends inside the whipper. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments that come within the spirit and scope of the present invention.