Abstract:
A method for producing a desired amount of ice crystal formation in a beverage comprising the steps of cooling said beverage to a temperature below its ordinary freezing temperature at atmospheric pressure to form a cooled beverage; maintaining said beverage at a pressure sufficient to inhibit freezing of said beverage; dispensing said cooled beverage into a vessel; obtaining a cooled surface, having a temperature sufficiently low to cause flash freezing of a portion of said cooled beverage which comes into contact therewith; and presenting said cooled surface to said beverage for a time sufficient to form a desired amount of said ice crystals in said beverage. An apparatus is provided for carrying out the method.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to methods and apparatus for cooling and dispensing beverages. More particularly, this invention relates to such a method and apparatus for practicing the method to produce ice crystals in a beverage as part of the dispensing of the beverage. 
   BACKGROUND OF THE INVENTION 
   There is nothing quite like a glass of cold beer on a hot day, yet all glasses of cold beer are not equal. They range from a slightly cool beer in a disposable plastic cup through a truly cold beer in a glass dripping with condensation to a frosty mug hazed with ice and frozen water droplets. While the latter presentation may not be optimal from a taster&#39;s perspective, it captures a certain suggestion of “cooling-off” which is absent in a slightly cool pub draught. 
   In venues where coldness is paramount to taste, such as for example a golf course on a scorchingly hot day or basking in the hot sun at an oceanside resort the ultimate expression of “cold and refreshing” is to achieve ice crystals in the beverage. While this may be achieved in juices and such by adding ice to a cold beverage, it is generally unacceptable with beer as the ice will dilute and spoil the taste of the beer as the ice melts. The alternative is to form ice crystals from water inherent in the beverage, be it beer, “soda pop” or perhaps wine or other spirit containing beverage. 
   While it is simple enough in theory to form ice crystals in a beverage, it has in practice heretofore been virtually impossible to do so with any degree of control over the quantity and the consistency of ice crystals so formed. Simply cooling beer to below its freezing point generally results in a block of “ice” if the container is left closed or frozen “slush” if the container is opened before the beer turns to “ice”. 
   It is therefore an object of the present invention to provide a method and an apparatus for practising the method for providing a controllable amount of ice crystal formation in at least beer and perhaps other beverages. 
   SUMMARY OF THE INVENTION 
   A method is provided for producing a desired amount of ice crystal formation in a beverage comprising the steps of:
         (i) cooling the beverage to a temperature near or below its ordinary freezing temperature at atmospheric pressure to form a cold beverage;   (ii) maintaining the beverage at a pressure sufficient to inhibit freezing of the beverage;   (iii) dispensing the cooled beverage into a vessel;   (iv) obtaining a cooled surface having a temperature sufficiently low to cause flash freezing of a portion of the cooled beverage which comes into contact therewith;   (v) presenting the cooled surface to the beverage during the dispensing for a time sufficient to form a desired amount of ice crystals in the beverage.       

   Once a desired amount of ice crystal formation has been achieved, the cooled surface may be at least one of, removed from contact with the beverage and allowed to warm to a temperature above which further ice crystals won&#39;t form. 
   The beverage may be beer cooled to temperature of from 23.0° F. to 28.0° F. and the pressure from 15 psi to 110 psi or higher. 
   The beverage may be dispensed through a dispensing tap with the pressure being reduced immediately upstream of the dispensing tap during dispensing to avoid splashing. 
   Preferably, if the beverage is beer with a 5% by volume alcohol content, the temperature in step (i) is from 24.0° F. to 27.0° F. and the elevated pressure is at least 60 psi. 
   A beverage dispensing apparatus is provided for chilling and presenting a vessel of the beverage with a portion of the beverage being in the form of ice crystals. The apparatus has a beverage inlet for receiving the beverage from a reservoir of the beverage. The apparatus further has a valved tap for dispensing the beverage into the vessel. A beverage conduit extends between the tap and the beverage inlet for providing fluid communication between the tap and the beverage inlet. A beverage pressurizer communicates with the conduit for increasing the pressure of the beverage to an elevated pressure sufficient to avoid freezing. A beverage cooler is associated with the beverage conduit for chilling at least the beverage within the conduit to a temperature below its freezing point at atmospheric pressure but above its freezing point at the elevated pressure. A pressure reducer is provided adjacent the tap for reducing the pressure of the beverage from its elevated pressure in the conduit to a pouring pressure to facilitate pouring from the tap when the tap is in an open configuration. The apparatus further has a flash freezer with a freezing surface for contacting the beverage during a pour of the beverage into the vessel to freeze a portion of the beverage to form ice crystals during the pour. A flash freezer cooler is associated with the flash freezer for chilling the flash freezing surface to a temperature sufficiently low to form the ice crystals upon contact. 
   The beverage cooler may include a length of the conduit and a coolant bath surrounding the length of conduit for receiving a chilled coolant to immerse the length of conduit. A beverage coolant refrigeration unit may be provided which communicates with the coolant in the bath for chilling the coolant. 
   The flash freezer cooler may include a flash freezer refrigeration unit for communicating with the freezing surface for cooling the freezing surface. 
   The beverage coolant refrigeration unit and a flash freezer refrigeration unit may be discrete units. 
   The length of the conduit immersed in the coolant bath may be in the form of a coil. 
   The pressure reducer may be a flow restrictor upstream of the tap. 
   The apparatus may further include a heater for heating the coolant in the bath should the coolant fall below a predetermined temperature and a sensor for sensing at least one of coolant temperature and beer temperature. The sensor and the heater communicate with a controller which activates and deactivates the heater and respectively deactivates and activates a pump which provides coolant flow between the coolant bath and the beverage refrigeration unit. 
   The controller may further communicate with and be configured to deactivate and activate the beverage refrigeration unit. 
   The flash freezer may be a cold probe which is passed through the beverage during pouring. 
   Alternatively the flash freezer may be a surface in the vessel and the flash freezer cooler a cold surface in contact with the vessel at least before the pour. 
   The flash freezer may be associated with or within the tap. 
   The flow restrictor may be at least one of a valve, an orifice and a reduced diameter length of the conduit. 
   A beverage vessel is provided for promoting ice formation of a cold beverage as it is dispensed into the vessel. The vessel has a base, a sidewall portion extending from the base and defining a mouth of the vessel opposite the base. A heat sink extends through and sealingly engages the base. The heat sink has an outer surface adjacent an outer face of the base for contacting a cooling surface and an inner surface opposite the outer surface adjacent an inner face of the base for contacting the beverage to draw heat from the beverage. The heat sink has a higher thermal conductivity than a remainder of the vessel. 
   The base and the walls of the vessel may be made of glass or plastic with the heat sink being made of metal. 
   The heat sink may preferably be an aluminium or copper based alloy. 
   A coolant jacket may be provided around the conduit adjacent the tap for circulation of the coolant about the conduit between the bath and the tap. 
   The coolant jacket may have an inlet fluidly communicating with the coolant bath through a cooling jacket pump connected between the coolant bath and the coolant jacket. An outlet of the coolant jacket may fluidly communicate directly with the coolant bath to act as a fluid return from the coolant jacket to the coolant bath. 

   
     DESCRIPTION OF DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the accompanying drawings in which: 
       FIG. 1  is a schematic representation of an apparatus according to the present invention; and, 
       FIG. 2  is an axial sectional view of a beverage glass for use in practice and embodiment of the present invention. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   A beverage dispensing apparatus (the “apparatus”) according to the present invention is generally indicated by reference  10  in the accompanying illustration. The apparatus  10  has a beverage inlet  12  for receiving a beverage  14  such as beer from a beverage reservoir  16  which may be a beer keg. A gas canister  18  may be provided to urge the beverage  14  from the reservoir to a beverage pressurizer such as the pump  20 . As will be described in more detail below, the pump increases the pressure of the beverage  14  (beer) in the apparatus  10  to depress its freezing point. 
   The pump  20  pumps the beer through a beverage conduit  22  at the opposite end of which is a valved tap  24 . The beverage conduit  22  has part of its length formed into a coil  26  which is immersed in a coolant bath containing a coolant  30 , such as glycol or any other suitable coolant, for cooling the coil  26  and in turn any beer (or other beverage  14 ) therein to a temperature below which it would freeze under atmospheric pressure (i.e. 1 atm) but above its freezing point at the elevated pressure caused by the pump  20 . 
   As the beverage  14  has a tendency to splash out of a vessel if dispensed at high pressure, a pressure reducer  32  is provided adjacent the tap  24 . The pressure reducer may be any one or a combination of a flow restricting orifice, a valve and a reduced diameter section of the beverage conduit  22 . 
   A flash freezer  34  such as the probe illustrated is provided adjacent the tap  24  for contacting the beverage during at least a portion of its pour. The flash freezer  34  has a freezing surface  36  which contacts the beverage as it is being poured into a vessel  40  filled to freeze and thereby to form ice from an aqueous portion of the beverage  14 . The temperature, heat transfer capabilities and contact duration selected will determine the nature and quantity of ice crystals. 
   A beverage cooler generally indicated by reference  50  and described in more detail below is provided for chilling the coolant  30 . A flash freezer cooler generally indicated by reference  100  and also described in more detail below is provided for chilling at least the freezing surface  36  to a temperature sufficiently low to cause ice crystal formation upon contact of the beverage  14  therewith. 
   The beverage cooler  50  includes a beverage coolant refrigeration unit  52 (“b/c refrigeration unit  52 ”) which may be a commercially available refrigeration system having evaporator coil  54  which is immersed in a beverage cooler glycol tank  56  (“b/c glycol tank  56 ”). The refrigeration unit  52  thermally communicates with the coolant bath  28  via a beverage coolant glycol line  60  (“b/c glycol line  60 ”) having an inlet  62  for admitting glycol  70  (or other suitable coolant) from the b/c glycol tank  56  and an outlet  64  for returning glycol  70  to the b/c glycol tank  56 . The b/c glycol line  60  includes a heat transfer coil  68  which is immersed in the coolant  30  in the coolant bath  28  to cool the coolant bath  28 . A pump  66  is provided in the b/c glycol line  60  to cause flow of glycol  70  from the b/c glycol tank  56  through the heat transfer coil  68  and back into the b/c glycol tank  56 . 
   The object of using the b/c glycol line  60  and b/c glycol tank  56  rather than directly trying to cool the coolant bath  28  with the b/c refrigeration unit  52  is to achieve better temperature control. Maintaining a supply of cold (approximately 15° F./−9° C.) of glycol  70  in the b/c glycol tank  56  and using a relatively high capacity pump  66  (about 2 gpm) allows better response to the intermittent thermal demands such as a pour than can be simply achieved with the b/c refrigeration unit  52  were it acting directly on the coolant  30  within the coolant bath  28 . 
   For even better control the coolant bath  28  can be set up as a “push pull” system by the addition of a heater  80  immersed in the coolant  30  in the coolant bath  28 . The heater  80  may be activated and the glycol pump  66  shut off if the temperature of the coolant  30  drops to or below a temperature set point. A controller  90  may be provided in communication with a temperature sensor  92  in the coolant bath, the heater  80  and the pump  66  to actuate and deactuate the heater  80  and the pump  66  as required. 
   A cooling jacket  80  may be provided around the beverage conduit  22  adjacent the tap  24  to maintain the portion of the conduit  22  between the coil  26  and the tap  24  cold between pours. The cooling jacket  80  may have an inlet  82  for receiving coolant  30  from the coolant bath  28 , an outlet  84  for returning coolant to the coolant bath  28  and a pump  86  for augmenting coolant flow. 
   The flash freezer cooler  100  is preferably provided with its own refrigeration unit  110  (the “ffc refrigeration unit  110 ”) as it generally requires lower temperatures than required for the beverage cooler  50 . 
   The ffc refrigeration unit  110  may be a commercially available unit having an evaporator coil  112  immersed in a flash freezer glycol tank  114  (“ff glycol tank  114 ”) with its own supply of glycol  120  (or other suitable coolant) typically cooled to a temperature of around −10° F. (−26° C.). A small pump  116  or other stirrer may be provided in the ff glycol tank  114  to circulate the coolant  120  to promote convective heat transfer between the evaporator coil  112  and the glycol  120 . 
   The ff refrigeration unit  110  thermally communicates with the flash freezer  34  for example through a flash freezer coolant line  130  (“ff coolant line  130 ”) having an inlet  132  for receiving glycol  120  from the ff glycol tank  114 , an outlet  134  for returning the glycol  120  to the ff glycol tank  114 . A pump  136  may be provided to cause flow of the glycol  120  along the ff coolant line  130 . 
   Alternatively a single refrigeration unit may be provided and set at a temperature suitable for cooling glycol for the flash freeze. In this case the glycol could be circulated either directly to the glycol tank  56  or indirectly through the heat transfer coil  68 . 
   As illustrated in  FIG. 1 , the flash freezer  34  may be in the form of a non-reactive metal probe (e.g. stainless steel) through which cold glycol  120  is passed by virtue of fluid communication with the ff coolant line  130 . The probe may be mounted so as to initially be pushed out of the way by the vessel  40 . The probe may be configured to initiate flow along the ff coolant line  130  in response to this motion. For example, the probe  34  may be connected to a switch  140  which activates the pump  136 . Once the pour has been initiated the vessel  40  may be lowered out of contact with the probe  34  to allow the probe  34  to move back through a stream  42  of the beverage  14  being dispensed from the tap  24 . 
   A biasing mechanism  144  such as a spring or the like may be coupled to the probe  34  to effect its movement back through the stream  40  of beverage  14 . 
   The above is but one possible arrangement for contacting a freezing surface  36  with the beverage  14 . Other arrangements will occur to one skilled in such apparatus. For example the freezing surface  36  may be integral with or attached to the tap  24 . The balance of the tap is preferably of relatively low thermal conductivity so as to avoid ice formation or its inadvertent acting as a flash freezing surface. Alternatively the vessel  40  may be provided with a freezing surface  36  as illustrated in  FIG. 2  and described below. 
   The vessel  40  has a base  42  and an upstanding sidewall portion  44  which defines a mouth  46  opposite the base  42 . A heat sink  48  extends through and sealingly engages the base  40 . The heat sink  48  has an inner flash freezing surface  36  adjacent an inner face  41  of the vessel  40 . The heat sink  48  has an outer cooling surfaced  49  opposite the flash freezing surface  36  and adjacent an outer face  43  of the vessel  40 . 
   In the  FIG. 2  embodiment the flash freezer cooler  100  may be a cold surface  150  for contacting the cooling surface  49  to draw heat out of the heat sink  48 . The flash freezer cooler  100  may be a thermally conductive plate  152  which is cooled by cold glycol  120  provided by the flash freezer coolant line  130 . 
   While for simplicity it is expected that the heat sink will be in the base  42  of the vessel, this is not an absolute requirement. For example, the heat sink could be a sleeve forming part of the sidewall portion  44  or may even form the entire base  42  and threadedly engage the sidewall portion  44 . Furthermore it may be desirable for sanitary reasons to have the flash freezing surface  36  adjacent to but covered by the inner face  41  rather than extending completely therethrough to avoid ingress of the beverage  14  therebetween. Also it may be desirable for the flash freezing surface continuous with rather than extending into the vessel  40 . 
   It is expected that the heat sink  48  will be a relatively good thermal conductor such as aluminium or cooper based alloys to promote rapid cooling of the freezing surface  36 , however stainless steel or other suitable material might also be used. The balance of the vessel will typically be of glass or plastic or ceramics as is commonly known for beverage vessels. Preferably the balance of the vessel will have at least some insulative properties so as to longer retain frozen any ice formed. 
   Theoretical analysis confirmed by empirical means shows that the temperatures and pressures needed to bring the beverages to the required state where freezing of some of the beverage into ice crystal forms was possible through the methods of this patent varied depending upon the chemical composition of the beverage. For instance, the optimum temperature range for ice formation in two beers having the same alcohol content, but different solute content, shifted by more than 1° F. A beer with an alcohol content of 5% by volume and under a high pressure froze at a temperature four degrees lower than a beer with an alcohol content of 4% by volume and under the same pressure. Pressure requirement also shifted depending upon variables such as CO 2  content and alcohol content. Accordingly, where beer is the beverage being presented with ice crystals in it according to the method and apparatus of the present invention, the temperature range is expected to vary from about 23.0° F. to approaching 32° F. (−5° C. to 0° C.). This is largely determined by the alcohol content. For a “5%” beer suitable results would be expected in a preferred range of about 24.0° F. to 27.0° F. (−4.4° C. to −2.7° C.). For higher alcohol beers (above 5%) or lower alcohol beers (4%, 3%) or even “non-alcoholic” (less than 0.5%) beers deviations toward opposite ends of the broader ranges above apply. Likely some “fine turning” will be required to suit particular brands even within a given alcohol content. 
   It is believed that the underlying mechanism is one of a solute being driven out of an aqueous solution in a local region adjacent the flash freezing surface by the flash-freezing temperature of the surface. More particularly, when a solute is dissolved in water (for example alcohol or an edible salt), the freezing point of the system is depressed. Presenting a localized heat drain (the flash freezing surface) causes the affected solution to dispel the solute with the resulting water freezing into ice crystals which then remain present in the now more concentrated solution. The foregoing theorem is however being proffered as a possible explanation is is not intended in a limiting or binding sense. 
   The above description is intended in an illustrative rather than a restrictive sense. Variations may be apparent to those skilled in the art without departing from the spirit and scope of the invention as defined by the claims set out below. For example if the flash freezing surface is cold enough it may be possible to achieve the desired result without the pressurization and cooling of the beverage below its atmospheric freezing point. There are limits to how warm one might want the beverage as having it warm will likely result in rapid melting of any ice crystals so formed. 
   The entire disclosure of Canadian Patent Application No. 2,448,893 filed Nov. 12, 2003 is hereby incorporated by reference.