METHOD AND APPARATUSFOR REMOVING CHARGED-MOLECULESOR CAFFEINE FROM AN AQUEOUS SOLUTIONThis is a continuation in part of U.S. application Serial No. 08/866,616, filed on May 30, 1997, now U.S. Patent No. 5,914,021 and incorporated herein by reference.Background of the InventionCaffeine is a partially water-soluble alkaloid. The removal of caffeine from natural products such as coffee beans, cocoa beans and tea leaves is important to many aspects of the beverage industry.Generally, caffeine has been removed directly from green or roasted beans or from caffeine-containing liquid by dissolving the caffeine in water or organic solvents or passing the caffeine-containing liquid over an ion exchange resin which attracts the caffeine. For example, L. Klein, U.S. Patent No. 1,039,961 discloses a process for decaffeinating coffee beans by employing mixtures of two or more alkali solvents. E. Burgen, U.S. Pat. No. 2,198,859 discloses heating raw coffee beans with the presence of an adsorption agent, such as activated carbon. H. Grossman, U.S. Patent No. 2,375,550 employs selective absorbents such as hydrated silicates to remove caffeine.H. Turken, et al., U.S. Patent No. 3,108,876 teach passing a coffee concentrate over an ionic exchange resin such as polystyrene sulfonic acid resins, carboxylic acid resins and polystyrene quaternary amine resins. G. Margolis, et al. U.S. Patent No. 4,031,251 disclose a decaffeination process using a non-ionic hydrophobic resin contacted with an aqueous extract of vegetable material.S. Katz, U.S. Patent No. 4, 113,886 discloses a process which permits caffeine to diffuse through a porous, hydrophilic membrane using a water- immiscible caffeine-specific solvent with a water phase on the opposite side of the membrane. G. van der Stegen, U.S. Patent No.4, 364,964 discloses a process for removing caffeine from green coffee beans using a synthetic resin which is
produced by a polymer containing aromatic ring systems and polar acidic groups.Each of these methods suffer from a number of disadvantages. None of the cited methods of decaffeinating a liquid are particularly adapted to producing a decaffeinated beverage simultaneously with brewing, for example, in the home or at a restaurant. Water and organic solvent employing systems must be performed in a commercial processing facility which adds to the cost of producing the beverage and requires that decaffeinated beverages must be sold separately packaged from caffeinated beverages (e.g. decaffeinated coffee products are sold separately from caffeinated coffee products). In addition, organic solvent systems are disadvantageous because of the environmental concerns of using such chemicals.The third method, employing synthetic resins to attract the caffeine in a caffeinated beverage, eliminates the use of costly solvent systems. However, the degree of attraction of the caffeine for the resins is limited and therefore such systems do not efficiently remove caffeine from caffeine-containing liquids. In additions, resins can deleteriously affect the taste of coffee.A device and method that employs an electrostatic field assembly for removing caffeine from caffeine-containing liquid is disclosed by the assignee herein in U.S. Patent No.s 5,443,709 and 5,503,724, each of which is incorporated herein by reference.Field of the InventionThis invention relates generally to devices and methods for removing a charged substance from a conductive liquid and more specifically to removing caffeine from a beverage.Summary of the InventionThe present invention comprises devices and methods for removing a charged molecule from an aqueous solution. One specific embodiment of the invention comprises devices and methods for removing caffeine from beverages
by incorporating an inventive decaffeinating device in a beverage brewer. Another specific embodiment comprises devices and methods wherein an aqueous reservoir chamber and porous separator is easily detached and replaced in the charged molecule, or caffeine, removal device.Summary Description of the DrawingsFigure 1 : shows an overall view of the inventive decaf einator incorporated into a brew-basket.Figure 2A: shows a top view of the replaceable aqueous reservoir chamber and porous separator unit.Figure 2B. shows a sectional view, cut through the line AA, of the replaceable aqueous reservoir chamber and porous separator unit.Figure 3: shows a detail view of the manifold for solution distribution, located in the replaceable cartridge, chamber, and porous separator unit.Figure 4: shows a graph of the amount of caffeine contained in each sequential cup of liquid flowing through a conventional brewer.Detailed Description of the InventionThe present invention comprises an apparatus having a cartridge that is divided into a plurality of chambers by a porous separator. Electrodes are located on opposing sides of the cartridge. The apparatus is manufactured so that the electrodes do not touch aqueous solution. The electrodes impose an inductive electric field across the cartridge and the chambers. Fluid flows from one chamber to the another through a porous separator in a direction opposing the imposed electric field.The present invention is not limited to removing caffeine from potable beverages. It can also be used to separated charged molecules from other aqueous solutions, for example, blood or other biological samples.
Figure 1, shows one embodiment of a device used to remove charged molecules from an aqueous solution. This embodiment was designed to remove caffeine from a brewed beverage such as coffee or tea during the brewing process. Figure 1 shows an exploded view of a caffeine removal device that is incorporated into a basket of a beverage brewer. The basket 2 has an orifice 4 to receive disk manifold 10. The orifice 4 is located where a drain hole would be located in a conventional brew basket. Liquid leaving the basket flows through orifice 4 into a replaceable disk element 6. Fluid enters the lower chamber 8 in the disk cartridge through a disk manifold 10. The fluid flows up through a porous separator 12 into an upper chamber 14. From the upper chamber 14 the fluid reenters the disk manifold 10 and drains down through an outlet 16 in the base assembly 18 of the decaffeinator. Upon leaving the base assembly 18 the fluid flows into a receptacle such as a coffee or tea carafe.Figure 2 shows two views of the replaceable disk element 6. Figure 2A shows a top view and Figure 2B shows a side view through section A — A. The disk encloses a plurality of chambers. In the embodiment shown there two chambers separated by a porous separator 12. The lower chamber 8 is located in the space between the lower disk cover 20 and the porous separator 12. The upper chamber 14 is located in the space between the upper disk cover 22 and the porous separator 12.The circular areas 24 depicted in Figure 2A, are two dimensional projections of dimples in the upper disk cover 22. Such dimples are not restricted of course to a circular cross-section or hemispherical shape as shown in the illustrated embodiment. The dimples serve as stand-offs, to keep a flexible porous separator 12 from touching against the upper cover 22, which would eliminate the upper chamber 14. The flexible porous separator 12 is exposed to an hydraulic pressure associated with the upward flowing liquid and the standoffs are necessary to counter that pressure against the porous membrane.Basket orifice 4 delivers fluid from the basket 2 to the lower chamber 8, through the disk manifold 10 through entrance channel 36. As the lower chamber
fills, it floods through the porous separator 12 and enters the upper chamber 14. When the upper chamber is filled, liquid flows through channel 34, then drains to exit channel 36 and into a receptacle (not shown).Figure 3 shows a detailed view of the disk manifold 10. Untreated liquid from the basket 2 drains through one or more channels 30 to orifices 32, in disk manifold 10 into the lower chamber 8. As the lower chamber fills, the untreated liquid moves through the porous separator 12, and into the upper chamber 14. From the upper chamber 14 the treated liquid flows out through channels 34 of disk manifold 10, into central exit channel 36, located in exit nipple 15 which fits into orifice 16 located in base 18. From the exit nipple 15, the treated fluid flows into a receiving receptacle (not shown).An electrostatic field is imposed across the disk element 6 by electrodes 38 and 40, shown in Figure 1 In the present embodiment an assembly of associated electrical components used to impose a voltage across the electrodes is contained in the base assembly 18. The replaceable disk element 6, the basket manifold 4, and the disk manifold 10, are watertight, preventing liquid from contacting and thus shorting out the electrodes Use of elaborately sealed electrodes is unnecessary.The electrodes comprise metal sheets having an area equal to or greater than the porous separator in the disk decaffeinator It is preferable, but not necessary, that the electrodes extend enough beyond the edges of the separator that fringe effects are minimized.The electrodes are typically made of solid sheets of metal. For cost efficiency and lightness, they may be electroplated on hard plastics, such as, for example, polystyrene or polyethylene However simple machined plates can be used too. Whatever geometry is used, the important criteria is that the field generated by the electrodes is approximately constant across their enclosed area.The voltage that is applied to the plates is typically in the range between about 100 volts (V) and about 1000 V More preferably, a range of between about
250 V and about 400 V is applied. Most preferably a potential of between about 300 V and about 375 V is applied between the electrodes. A 9 V battery can be used to supply the voltage or other sources can be used. The voltage source is connected to the electrodes using electrical connectors attached to the electrodes.Separation of charged molecules from the aqueous solution is achieved by application of an electrostatic field across the chambers 8 and 14, and across the porous separation means. The aqueous solution flows from the bottom chamber 8, through the porous separator 12, to the upper chamber 14. To remove a molecule having a positive charge from the liquid, the flow of the liquid is toward the positive electrode. The applied electrostatic field induces an electric field of opposite orientation across the porous separator 12. For example, a relatively positive charge on electrode 38 will induce negative charges to migrate to the upper surface of separator 12 which in turn will leave relatively positive charges on the lower surface of the separator, the surface that borders the lower chamber 8. Thus, as positively charged molecules, such as for example caffeine, enter chamber 8 they are attracted to the bottom surface near the relatively negatively charged electrode and are repelled from separator 12 which has a positive charge on its lower surface. By this mechanism, the positively charged molecules are selectively retained in the lower chamber.However, as more and more positively charged molecules, such as for example caffeine, continuously enter lower chamber 8, the concentration of positively charged molecules increases until the individual charged molecules become so concentrated that they develop an internal space charge. As the internal space charge increases the efficiency of the charged particle removal activity increases. When the internal space charge exceeds the applied electrostatic field, the positively charged molecules can no longer be retained in the lower chamber.One way to maintain optimum removal of charged molecules, is to frequently clean the cartridge, chamber, and separator assembly. Because this can be labor intensive and cause leaks it is more advantageous to replace the chamber
and separator assembly. The present invention makes replacement of the entire chamber and separator assembly, without sacrificing mechanical integrity, particularly easy to do. The cartridge, chambers, and separator assembly is manufactured as a replaceable modular element, conveniently referred to as a "disk decaffeinator".The disk decaffeinator is shown in drawings 1 and 2 as it is used for a beverage decaffeination. When manufactured inexpensively enough, it becomes economically feasible to use as a replaceable or disposable disk decaffeinator. It is an advantage of this embodiment that the disk decaffeinator can be made inexpensively. The disk manifold 10 is, in contrast, extremely simple to manufacture, having a plurality of upper and lower orifices 26 and 28 that are relatively simple to produce in any of a number of materials.The disk decaffeinator as shown in the preferred embodiment is substantially shaped like a cylinder with channels through which liquid can flow before, during, and after the liquid is treated. The cylinder is divided into two chambers 8 and 14 by a porous separator 12. Liquid enters and leaves the cylinder via channels in the disk manifold. Liquid moves from one chamber to another via the porous separator. In the embodiment shown in Figure 2, the chamber is formed from four elements: a domed circular member 48 forms the upper chamber; a cylindrical member having one closed end 20 forms the lower chamber 50; a center fluid manifold forms the disk manifold 10; and a membrane separator 12 divides the chamber into two chambers. The final shape of the disk decaffeinator is approximately cylindrical, with a lip at the point where the component members are joined, for example by ultrasonic or solvent weld 42. Three elements are joined at lip 42: the upper chamber 14, the membrane separator 12, and the lower chamber 8. Ultrasonic or solvent welds also join the disk manifold 10 to the component members of the chamber.In one embodiment the disk decaffeinator was manufactured from plastic.In that embodiment the disk was made with polystyrene and the edges 42, 44, and 46 of the disk were sealed using ultrasonic welding. Solvent sealing may be used
as an alternative. Alternatively any of several other plastics such as polyethylene can be used, provided that they are rigid.The top surface of the disk decaffeinator 22 contains depressions or dimples that bear on the porous separator 12 to prevent it from being carried upwards by the solution flow and possibly touching against the top surface. Many types of mechanical standoffs can be used other than dimples. Standoffs to prevent a flexible member from collapsing against a nearby rigid member are well known in the mechanical arts and any of the well known standoff configuration can be used. A dimple configuration was used in the present embodiment because of the manufacturing ease it presented. Standoffs are, of course, only necessary in the event that the porous separator 12 is made from flexible or moveable material. If the separator is rigid there is no need for the dimples in the top surface. The porous separator 12 may be made of porous stainless steel, nitrocellulose supported ionic resins, zeolites or other ionic species. Other types of solid supports can be substituted for nitrocellulose.It is important that the filter or membrane used as a porous separator is thick enough to provide structural support, but not so thick that beverage flow through it is reduced unacceptably.Some advantages of a disposable disk decaffeinator include, ease of maintaining cleanliness, use of an opaque plastic to prevent of unsightly discoloration of the porous separator, prevention of clogging problems with the porous separator, and maintenance of consistent flow rates for every pot of coffee.Another advantage of the disk chamber design is the ease with which the brewer configuration can be modified. For example, to increase the flow rate of the decaffeination step, the stream of untreated brewed beverage can be divided into to two or more streams. Each stream can be simultaneously directed to one of a plurality of disk decaffeinators, then the streams can be all delivered into the same receptacle. Alternatively, the multiple disk decaffeinators can be stacked vertically, each disk having its own pair of electrodes, run in parallel off the
battery.Several design features have been included to provide safe use of the inventive decaffeinator. For example, the magnet 52 closes reed switch 54 only when the basket is engaged with the disk decaffeinator base. This prevents the electrodes from being activated if the decaffeinating circuitry is switched 'on' when the unit is not properly assembled. Additionally, the disk manifold is preferably designed so that the basket and disk will only fit together when the disk decaffeinator is properly oriented.Furthermore, the disk decaffeinator is preferably configured so that the manifold 10 is made integral to the disk, fitting into a simple fluid distributor in the disk unit. The exit nipple in this design is made integral to the disk decaffinator.ExampleIn one embodiment the decaffeinating brewer was assembled by inserting a replaceable disk 6 into the bottom of the basket 2. The upper portion of disk manifold 10 was inserted into orifice 4 of the brew basket. The base 18 was then secured to the basket 2 with exit nipple 15 extending through orifice 16. The replaceable disk decaffeinator was thus located between a positive electrode 38 and a negative electrode 40. An enclosed battery 48 and power supply 50 was located in the handle of the base cover 18. A magnet 52 located in the bottom of the basket handle was used to close a reed switch 54. The decaffeination process was only activated when both reed switch 54 and external switch 56 were 'on'.This requirement acted as a security feature to prevent power from being applied to electrode 38 when the unit was disassembled. Preferably a light 58 can be activated when the decaffeination process is underway. Water tight seals retained all moisture in the disk manifold and internal chambers so that the electronics were not exposed to aqueous elements.Figure 4 shows a graph of caffeine concentration, in mg/ml, measured using high performance liquid chromatography, as a function of volume brewed in
a commercial beverage brewer. Aliquots of 125 ml were removed sequentially from the brewed stream. As the graph and chart in the upper right hand corner of the figure shows, the majority of the caffeine is released within the first three cups in the brewing cycle. The membrane and electrostatic field must have the capacity to decaffeinate the caffeine concentrations at the peak value. The average caffeine per cup after the entire pot is brewed, is indicated by the dashed line.Decaffeination performance was also measured using high performance liquid chromatography. The disk decaffeinator reduced caffeine content by 65% to 84% from the regularly brewed coffee.The description of illustrative embodiments and best modes of the present invention is not intended to limit the scope of the invention. Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the appended claims.10
We claim:
1. An apparatus for removing a charged molecule from an aqueous solution comprising, a) a holding reservoir for a volume of untreated liquid, the holding reservoir having an exit orifice; b) a first electrode located downstream of the exit orifice; c) a cartridge located downstream of the first electrode, the chamber comprising, i) a top wall and a bottom wall positioned approximately parallel to each other and aligned sequentially downstream of the exit orifice, the top and bottom walls connected by at least one sidewall; ii) a first and a second chamber having a common inner wall formed from a porous separator situated approximately parallel to the top and bottom walls and located between them;
A) the first chamber having an outer wall formed from the bottom wall and at least one side wall;
B) the second chamber having an outer wall formed from the top wall and at least one side wall; d) a fluid manifold connecting the exit orifice of the holding chamber with an entrance channel to one of the chambers and connecting the other chamber to an exit channel; e) a second electrode located downstream of the chamber; f) a base supporting the second electrode and having an exit nipple connected with a watertight seal to the exit channel of the fluid manifold; g) electrical connectors.
2. The apparatus of claim 1 wherein the cartridge is shaped in an approximately cylindrical configuration wherein the top and bottom walls
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span the top and bottom of the cylinder and the height of the sidewall is smaller than the diameter of the cylinder to form the profile of a disk.
3. The apparatus of claim 1 wherein the top wall of the chamber has standoffs.
4. The apparatus of claim 3 wherein the standoffs are dimples.
5. The apparatus of claim 3 wherein the cylinder is substantially made of plastic.
6. The apparatus of claim 5 wherein the plastic is polystyrene or polyethylene.
7. The apparatus of claim 2 wherein the chamber further comprises fluid distribution orifices that match inlets and outlets in the fluid manifold.
8. The apparatus of claim 1 where in the porous separator is formed from a porous rigid material.
9. The apparatus of claim 8 wherein the porous separator is formed from nitrocellulose containing an ionic compound.
10. The apparatus of claim 1 wherein the fluid manifold, first and second chambers, and exit nipple form a water tight fluid path.
11. The apparatus of claim 1 wherein the electrodes are made from electroplated, chemical vapor deposited, or sputtered metal plating.
12. The apparatus of claim 1 wherein the electrodes are made from metal sheeting.
13. The apparatus of claim 1 wherein the holding chamber comprises a brew basket.
14. The apparatus of claim 1 wherein the base further comprises a safety interlock with the holding chamber.
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15. The apparatus of claim 1 wherein the electrical contacts are connected to a voltage supply.
16. The apparatus of claim 15 wherein the voltage supplied is between about 100 V and about 1,000 V.
17. The apparatus of claim 15 wherein the voltage supplied is between about
250 V and about 400 V.
18. The apparatus of claim 15 wherein the voltage supplied is between about 300 V and about 375 V.
19. An apparatus for brewing and decaffeinating beverages comprising, a) a brew basket having an exit orifice; b) a first electrode located downstream of the exit orifice; c) a disk decaffeinator, the disk decaffeinator comprising a cartridge divided by a porous separator into a first and a second chamber, one chamber located downstream of the other; d) a fluid manifold, extending through the first electrode into the disk decaffeinator, and connecting the exit orifice of the brew basket with an entrance channel to one of the chambers and connecting the other chamber to an exit channel; e) a second electrode located downstream of the disk decaffeinator and having an opening for the fluid manifold to extend through; f) a base supporting the second electrode and having an exit orifice coupled with a watertight seal to the exit channel of the fluid manifold; e) electrical connectors.
20. The apparatus of claim 19 wherein the first chamber to which the fluid manifold delivers fluid is the chamber farthest away from the brew basket.
21. The apparatus of claim 19 wherein the disk decaffeinator element is disposable.
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22. The apparatus of claim 19 wherein the voltage between the first and second electrodes is between about 300 volts and about 400 volts.
23. The apparatus of claim 19 wherein a plurality of disk decaffeinator elements are located between the brew basket and the exit orifice.
24. The apparatus of claim 23 wherein a plurality of disk decaffeinator elements are located vertically between the brew basket and the exit orifice.
25. An apparatus for brewing and decaffeinating coffee or tea comprising, a) a brew basket having i) an exit orifice ii) an electromagnetic interlock element; and iii) a mechanically compatible interlocking shape on the bottom surface of the basket to connect to the top of a disk decaffeinator; b) a first electrode located below the exit orifice, the electrode having an opening for a fluid manifold to extend through the electrode; c) a disk decaffeinator, the disk decaffeinator comprising a chamber divided by a porous separator into a first and a second chamber, one chamber located below the other, the top of the disk decaffeinator having a shape that interlocks with the brew basket.; d) a fluid manifold, extending through the first electrode into the disk decaffeinator, and connecting the exit orifice of the brew basket with an entrance channel to one of the chambers and connecting the other chamber to an exit channel; e) a second electrode located below the disk decaffeinator and having an opening for the fluid manifold to extend through; f) a base supporting the second electrode and having an exit orifice coupled to the exit channel of the fluid manifold, the base further comprising a magnetically activated safety switch; and e) electrical connectors.
26. The apparatus of claim 25 wherein the fluid manifold, top and bottom
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chambers, and exit nipple form a water tight fluid path.
27. The apparatus of claim 25 wherein the first chamber to which the fluid manifold delivers fluid is the chamber farthest away from the brew basket.
28. The apparatus of claim 25 wherein the voltage between the first and second electrodes is between about 300 volts and about 400 volts.
29. The apparatus of claim 25 wherein a plurality of disposable disk decaffeinator elements are located between the brew basket and the exit orifice.
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