FR2761235A1 - Small scale decaffeination of coffee or tea by electrolysis - Google Patents

Abstract

The caffeine in coffee or tea is degraded by electrolysis of the brewed liquid. The process is carried out in an adapted domestic filter coffee maker (14) with a degradation unit (20) positioned beneath the filter outlet (23).

Description

PROCESS FOR DEGRADING CAFFEINE FROM COFFEE INFUSION
OR TXE AND APPARATUS FOR IMPLEMENTING THIS METHOD
The invention relates to methods for degrading caffeine from a coffee or tea infusion flowing from a filtration device containing a certain amount of coffee or tea.

 Currently, we offer for consumption so-called decaffeinated infusions industrially prepared from treated coffee beans from which the caffeine has been chemically removed. These drinks because of their preparation and their special packaging for sale have a significant added value which is an obstacle to a large distribution.

 As it has become one of the necessities of our daily life to be able to offer consumers the choice of drinking normal coffee or decaffeinated coffee, various decaffeinization processes have been developed industrially but few can be transposed to the public .

 One of the known methods responding to this demand is described, for example, in PCT patent application nOW095 / 16358 in which the caffeine is trapped by subjecting the coffee infusion to an electrostatic field established between two electrodes. In addition to the obligation to guarantee perfect electrical insulation due to the presence of a potential rising between 1000 and 3000 volts, this process uses a sensor to trap caffeine based on resin. This sensor, npn only, must be regularly washed and maintained, but also has the major drawback of rejecting the trapped compounds during the infusion when said resin is saturated. On the other hand, the use of resin in a humid and hot environment leads the user to respect perfect hygiene to avoid any microbial proliferation harmful to health.

 The present invention therefore aims to provide a new process for degrading caffeine which can be implemented both in industry and in the public and which does not have the drawbacks mentioned above.

 According to the invention, the method consists in carrying out an electrolysis of the infusion.

 Thanks to this process, caffeine, the polar compound contained in coffee or tea, is degraded into other chemical compounds until even its total CO 2 destruction is obtained. This electrochemical device therefore judiciously ensures oxidation of the caffeine, making it possible to obtain an excellent coffee drink reduced in caffeine while preserving its aromas.

 Although this process can be applied to large volumes of infusion stored in electrolytic cells, it is advantageous to provide for the continuous treatment of the infusion.

 According to another characteristic of the invention, the infusion flowing from a filtration device containing a certain quantity of coffee or tea, the electrolysis operation consists in - forming a flow path in a chamber comprising at minus a pair of electrodes - apply an electric current emanating from a direct current source between the electrodes to electro chemically oxidize the caffeine in coffee or tea in order to obtain in particular its degradation.

 This method also comprises an operation for collecting the treated infusion flowing from said chamber.

 Thus, it will be understood that as the infusion is made, it flows according to a preferred path in which the electrolysis is carried out continuously to reduce the time for degradation of the caffeine by a more localized and therefore more complete oxidation, while consuming less current.

 According to yet another important characteristic of the invention, the method for degrading caffeine is directly applied to a household appliance or household appliance such as a coffee maker, and implemented in a degradation device arranged under an outlet chute of the infusion.

 Thanks to the arrangement of this degradation device, the user is offered the choice of making an infusion of coffee or tea at will containing more or less and even very little caffeine from coffee or tea.

The characteristics and advantages of the invention will be better understood from the following description given by way of example and made with reference to the accompanying drawings in which
- Figure 1 is a diagram illustrating the different steps of the method according to the invention
- Figure 2 shows schematically in vertical section an electric coffee maker comprising a filtration device equipped with a caffeine degradation device implementing the method according to the invention.

 In FIG. 1, a flow diagram of a coffee or tea infusion loaded with caffeine from a filtration device 1 containing a certain quantity of coffee or tea 2 and subjected to different steps of a process for degrading caffeine from said infusion.

This illustration of the process explains both a degradation device capable of being used in industry for making coffee-beverages conditioned in individual packages of small volume, as a degradation device used by the public and mounted on devices. household appliances such as for example a coffee machine shown diagrammatically in FIG. 2.

 According to the invention, the method is characterized in that an electrolysis of the infusion is carried out. Preferably the electrolysis is carried out on a moving infusion and consists of forming a flow path 3 in a chamber 4 comprising at least one pair of electrodes 5,6, applying an electric current emanating from a source of direct current and distributed between the electrodes to electrochemically oxidize the caffeine in coffee or tea in order to obtain in particular its degradation.

 Then, an operation of collecting the treated infusion flowing from the infusion chamber 4 is carried out.

 The electrochemical process described above makes it possible to obtain a priority oxidation of caffeine and uses a direct current source ensuring a current between the electrodes 5, 6 whose characteristics are directly linked to the infusion rate to be treated and to its content. caffeine. It is the same for the number of pairs of electrodes which is in no way limited to one.

On the other hand, in order to be able to comply in particular with European directives, the electrodes must in particular comply with the following parameters - food quality - neutral with respect to coffee - not degradable by electrolysis - operating durability - resistant to a temperature in the range of 70
at l000C - non-stick for oxidation products.

 In a preferred embodiment, a counter electrode connected to the negative pole of the current source and made of stainless steel is used, as well as a so-called working electrode connected to the positive pole of the current source and made of carbon.

 By carbon electrode is meant, for example, a polygranular graphite or glassy or composite carbon.

 Other pairs of electrodes can be used to carry out the electrochemical oxidation process without departing from the invention. For example, we can use the carbon and platinum couple.

 Of course, the characteristics of the current between the electrodes will be harmonized with the different couples used and with the infusion rates to be treated.

For example, in tests carried out on low flow rates the carbon / platinum couple works well with a potential of 1.65 stud, while with the carbon / stainless steel couple a potential of 2.15 Volts is necessary.

 According to a first application of the invention (not shown), the method is intended to be applied to a household appliance comprising a filtration device comprising a housing containing a paper or metal filter receiving a certain quantity of coffee grounds on which hot water is poured out, said housing having an outlet chute for the infusion thus produced. In order to transform the coffee infusion into a coffee infusion reduced in caffeine, a degradation device is implemented under the outlet chute which implements the method described above and which for this purpose comprises a chamber having an orifice inlet communicating with the outlet chute and an outlet orifice communicating with a cup or an infusion collecting pot and having a flow path arranged between these two orifices, said chamber having a working electrode and a counter electrode placed in said path. In this embodiment, the flow of the infusion is by gravity. This filtration device can thus equip any existing coffee or teapot, provided of course that there is a direct current source for electrolysis, said current source being able to be a storage battery, a solar charger for camping or a rectifier placed on an alternative electrical network.

 According to a second preferred application of the invention illustrated in Figure 2, the method is intended to be applied to a household appliance, such as a coffee or tea maker, comprising a cold water tank 10, a water heater 11 said with circulation, a hot water ascent tube 12 whose outlet 13 sprinkles a filtration device 14. This filtration device comprises a housing 15 containing a filter 15 ′ of paper or metal intended to receive a certain quantity of grind normal coffee onto which the hot water is poured, the temperature of which is in the range from 70 to 1000C, said casing having an outlet chute 16 for the infusion thus produced.

 The filtration device 14 can either be integral with the casing of the coffee maker as shown diagrammatically in broken lines by a trigger guard 17, or rest directly on the edge 18 of a pot 19 infusion collector.

To apply the method according to the invention to such a coffee maker, a degrading device 20 is arranged under the outlet chute 16 which comprises a chamber 21 which is delimited by a wall 22 having an inlet orifice 23 communicating with the chute. outlet 16 and an outlet orifice 24 communicating with the pot 19, and which comprises a flow path referenced by the letter C. Said chamber comprises a working electrode referenced by the same reference 5 as that described above and a counter electrode 6 placed in said path.

 If we consider in more detail these different constituent elements and as shown, the chamber has the shape of a circular flattened hollow body whose wall 22 includes an upper face 25 receiving the inlet orifice 23, a lower face 26 receiving the outlet orifice 24 and a lateral face 27.

 According to another characteristic of the invention, the wall 22 of the chamber is made of a metallic material, preferably but not necessarily, such as stainless steel, and thus constitutes the counterelectrode 6. For an embodiment economical, the upper 25 and lower 26 faces of the wall 22 each have the shape of a cup, and their edges are welded to one another to form the lateral face 27. Preferably, the cups have a similar shape and can thus be produced by a single stamping tool.

 Still with the aim of achieving an economic and minimal space requirement, the working electrode 5 has the shape of a flat disc arranged practically parallel to the upper 25 and lower 26 faces, and kept inside said chamber at a distance from the wall 22 by means of spacers 28 made of electrically insulating and heat-resistant material such as, for example, a silicone.

 In order to provide the flow path C, the periphery 29 of the disc of the working electrode 5 is located at a certain distance from the lateral face 27. It is also advantageous to lengthen the path C by arranging the orifices inlet 23 and outlet 24 in the central regions of the upper 25 and lower 26 faces.

 Finally, it is particularly advantageous to guarantee the parameters of the electrodes mentioned above, in particular food quality and non-degradability by electrolysis, to produce the working electrode 5 in a disc made of carbon material. The nature of the carbon used is an important element of the invention, because it acts on the rate of degradation and the adsorption of organic compounds.

 In order to promote the electrolysis of the caffeinated coffee infusion, the spaces located between the flat disc forming the working electrode 5 and the upper 25 and lower 26 faces are lamelliform.

 To guarantee the proper functioning of the electrolysis, the counter electrode 6 comprises a pad 30 connected directly to the negative pole of the current source, while the working electrode 5 is connected to a pad 31 connected to the positive pole of said source and electrically isolated from the counter-electrode by an electrical insulating sleeve 32 passing through the upper face 25 of the wall 22. To ensure good electrical contact between the pad 31 and the fragile surface of the carbon disc constituting the working electrode 5 , provision is made to interpose a contact spring 33 between this stud and the disc.

 To fully understand the surprising advantages of this degradation process which have only been confirmed following major research, the implementation of this process will be described in conjunction with the coffee maker illustrated in FIG. 2.

 The coffee maker being put into operation and the degradation device being connected to a DC power source by means of a selector switch (not shown), the hot water sprinkles through outlet 13 the ground coffee contained in the device filtration 14.

 As the hot water passes (around 90 "C) through the grind, an infusion of coffee heavily loaded with caffeine flows by gravity through the outlet chute 16, enters the chamber 21 through the orifice 23, follows the flow path C formed by the disc of the working electrode 5 and the wall 22 of the counter-electrode 6, then exits through the orifice 24 to be collected in the pot 19. The infusion path is represented schematically by a series of arrows Thanks to the flat shape of the chamber and the lamelliform path, electrolysis takes place over a large area and under low voltage, for example 1.6 Volts and with a current which can vary from 10 to 400 2 mA / dm2.

 This electrolysis process for the degradation of caffeine in coffee or tea also offers the possibility of carrying out an automatic cleaning of the electrodes by reversing by means of an inverter (not shown) the direction of the current and therefore the polarity of these electrodes.

 Of course, the invention is not limited to the exemplary embodiments which have just been described and modifications can be made such as, for example, degradation devices using a chamber with several disks stacked at a distance from each other. others to form a longer path for the infusion in order to achieve the elimination of caffeine. Also, it is possible to use other types of electrode, in particular electrodes in the form of a grid or else in the form of a perforated disc.

Claims (14)

 1. Method for degrading the caffeine of an infusion of coffee or tea, characterized in that an electrolysis of the infusion is carried out.  2. Method according to claim 1, characterized in that the infusion flowing from a filtration device (1,14) containing a certain quantity of coffee or tea (2), the electrolysis operation consists in - forming a flow path (3) in a chamber (4,21) comprising at least one pair of electrodes (5,6) - applying an electric current emanating from a direct current source between the electrodes to electrochemically oxidize the caffeine from coffee or tea with a view to obtaining in particular its degradation; and in that it comprises an operation for collecting the treated infusion flowing from said chamber.  3. Method according to claim 2, characterized in that it uses a counter-electrode (6) connected to the negative pole of said current source, and an electrode (5) called working connected to the positive pole of said current source , said electrodes having at least the following parameters: food quality, not degradable by electrolysis, temperature resistant in the range from 70 to 1000C.  4. Method according to claim 3, characterized in that the counter electrode (6) is made of a metallic material and the working electrode (5) is made of carbon.  5. Household appliance comprising a filtration device (1,14) comprising a housing containing a filter and having an outlet chute for infusion, characterized in that it comprises a degradation device (20) arranged under the chute and implementing the method according to claims 1 to 4.  6. Household appliance comprising a cold water tank (10), a water heater (11) connected to this tank and delivering hot water to a filtration device (14) comprising a housing (15) containing a filter (15 ') and having an outlet chute (16) for infusion, characterized in that it comprises a degradation device (20) arranged under the chute (16) and implementing the method according to claims 1 to 4.  7. Household appliance according to claim 6, characterized in that the degradation device (20) comprises a chamber (21) which is delimited by a wall (22) having an inlet orifice (23) communicating with the outlet chute (16) and an outlet (24) communicating with an infusion collector pot (19), which comprises a flow path (C) for the infusion, as well as a working electrode (5) and a counterelectrode (6) placed in said path (C).  8. Household appliance according to claim 7, characterized in that the chamber (21) has the shape of a flattened hollow body, the wall (22) of which comprises an upper face (25) receiving the inlet orifice (23) , a lower face (26) receiving the outlet orifice (24) and a lateral face (27).  9. Household appliance according to claim 8, characterized in that the wall (22) of the chamber (21) is made of a metallic material and constitutes the counter-electrode (6), while the working electrode (5) is kept inside said chamber at a distance from the wall (22) by means of spacers (28) of electrical insulating material, said chamber providing the flow path (C) between the inlet orifices (23) and outlet (24).  10. Household appliance according to claim 9, characterized in that the working electrode (5) has the shape of a flat disc arranged practically parallel to the upper (25) and lower (26) faces and whose periphery (29) is located at a certain distance from the lateral face (27) of the chamber (21) thus providing the flow path (C).  11. Household appliance according to claim 10, characterized in that the spaces between the flat disc forming the working electrode (5) and the upper (25) and lower (26) faces are lamelliform.  12. Household appliance according to claim 10 or 11, characterized in that the working electrode (5) is a disc made of carbon material.  13. Apparatus according to any one of claims 5 to 12, characterized in that an electric current is applied between the electrodes (5,6) whose characteristics are located in potential in the range from 1 to 5 volts and 2 in density in the range of 10 to 400 mA / dm  14. Apparatus according to claim 13, characterized in that it comprises an inverter for changing the direction of the electrolysis current in order to obtain an automatic cleaning of the electrodes.