System for filtering and adjusting the electrolytic composition of water for an espresso coffee machine and related espresso coffee machine

Abstract

Disclosed herein is a machine for preparing and dispensing espresso coffee, the machine comprising a system for adjusting the electrolytic composition of water used in the preparation of espresso coffee, the system comprising a water demineralizer and a device for adding at least one organic and / or inorganic salt to the demineralized water.

Description

[Technical Field]

[0001] The present invention relates generally to the field of beverage preparation machines, and more particularly to a system for filtering and adjusting the electrolytic composition of water for an espresso coffee machine, as well as to an espresso coffee machine comprising such a system and a method for controlled extraction of coffee. [Background technology]

[0002] Water is the most important ingredient in espresso coffee, quantitatively, and after the coffee itself, it is the ingredient that has the greatest influence on the taste of the drink.

[0003] Apart from the different types of processes used to obtain the beverage, what remains fundamental beyond the primary product (coffee) is the "extract". It is no coincidence that 95-98% of a cup of coffee, from espresso to filter coffee, from mocha to boiled, is made up of water. This essential element can contain various substances capable of modifying the final result of the beverage, in terms of the volatile aromatic compounds extracted and its flavor. In fact, water can be considered not only as an inert, colorless, tasteless, odorless solvent, but also as an "ingredient" that is fundamental in every respect to its final quality.

[0004] The Applicant now notes that the chemical composition of the water delivered to coffee machines varies greatly when considering different parts of the same country, and even when considering different countries.

[0005] Water supplied by public water supplies actually contains variable amounts of salts and is characterized by variable values ​​of parameters such as hardness, i.e. calcium and magnesium ion content, and pH.

[0006] These differences have a significant impact on both the correct operation and duration of the coffee machine and the quality of the resulting beverage, making it virtually impossible to control and standardize the performance of machines installed in different parts of the world.

[0007] With regard to the correct operation and durability of an espresso coffee machine, for example, the use of water with a high content of calcium and magnesium ions can, if not treated appropriately, lead to the formation of very unpleasant deposits even within a short period of time due to the precipitation of insoluble salts such as calcium carbonate and magnesium hydroxide.

[0008] To solve this problem, it is known to use water softened with ion exchange resins, which replace the ions that cause hardness with sodium ions, thus preventing the deposition of limestone (calcium and magnesium carbonates).It is also known to use fully demineralized water, which is then resalinated in an uncontrolled manner. Summary of the Invention [Problem to be solved by the invention]

[0009] The applicant notes that both strategies dramatically change the chemical composition, and therefore the chemical and physical properties, of the water used to extract coffee. Moreover, the applicant notes that this can have undesirable effects on the organoleptic properties of the resulting beverage. Furthermore, demineralized water, especially when heated, can be aggressive to coffee machine components.

[0010] The term "specific ion effect" or "Hofmeister effect" is used to describe a series of physicochemical phenomena caused by organic molecules dissolved in aqueous solutions containing salts. The most studied of these phenomena is the variation of the solubility of organic molecules in aqueous solutions with the variation of the electrolyte composition of the solution.

[0011] The Applicant therefore focused on whether the chemical composition, and in particular the electrolytic composition, of the water used in espresso coffee machines could alter the solubility of organic molecules contained in the ground coffee, thus favoring their extraction during coffee preparation.

[0012] In fact, the preparation of espresso coffee can be considered as a series of steps of extraction of substances from a porous organic matrix (coffee grounds) by a polar solvent (water), and is therefore conditioned by the distribution between the two phases and thus the relative affinity of each substance for the two phases.

[0013] However, although the relationship between the water solubility of organic molecules and the presence of salts has long been studied for macromolecules such as proteins and nucleic acids, it appears that this has not been studied for small organic molecules. In particular, to the applicant's knowledge, there have been no systematic studies in the prior art on the effect of ions on the water solubility of small organic molecules under high temperature and pressure conditions, nor have there been any reports in the art on how to use this effect in extraction processes from organic matrices of interest to the food industry.

[0014] In order to control and / or standardize the characteristics of espresso coffee, the applicant aimed to develop a system and method for controlled extraction of organic molecules present in ground coffee, useful during the preparation of espresso coffee, to obtain, for example, a beverage with desired organoleptic properties.

[0015] Advantageously, the system and method also allows the water used to prepare espresso coffee to be less corrosive or abrasive to the components of the espresso coffee machine.

[0016] Advantageously, by means of a method based on specific ionic effects, the electrolytic composition of the water used can be adjusted to control the chemical composition and therefore the organoleptic properties of the coffee extract obtained. [Means for solving the problem]

[0017] According to a first aspect, the present invention relates to a method for controlled extraction of at least one organic molecule present in ground coffee during the preparation of espresso coffee in a machine for preparing and dispensing espresso coffee, said method comprising the following steps: a) Desalination of water. b) adding at least one organic and / or inorganic salt to the demineralized water. c) preparing espresso coffee using the water thus obtained.

[0018] Advantageously, the method according to the invention further comprises a step of filtering the water.

[0019] According to one embodiment, the at least one organic and / or inorganic salt is added in step b) in the form of one or more aqueous saline solutions prepared from demineralized water.

[0020] According to one embodiment, the at least one organic and / or inorganic salt is added in solid form to the demineralized water in step b).

[0021] According to one embodiment, the at least one organic and / or inorganic salt is added in step b) to the demineralized water both in solid form and in the form of one or more aqueous salt solutions prepared from the demineralized water.

[0022] Preferably, the addition in step b) of the process according to the invention is carried out with homogeneous mixing.

[0023] Advantageously, the addition in step b) is made in proportion to the water flow required by the machine.

[0024] In particular, the desalting of step a) according to the invention can be total or partial. Preferably, the desalting is total.

[0025] Preferably, the at least one salt added in step b) according to the present invention is an inorganic salt.

[0026] Preferably, the inorganic salt is selected from the group comprising sodium, potassium, magnesium and calcium salts, and even more preferably, the inorganic salt is selected from the group comprising potassium chloride, sodium chloride, magnesium chloride, calcium chloride, potassium sulfate, potassium nitrate, calcium sulfate and magnesium sulfate.

[0027] Advantageously, the amount of salt added in step b) according to the present invention can be adjusted based on the water flow required by the machine using an aqueous solution containing one or more selected salts at an appropriate concentration. Generally, the concentration of the aqueous salt solution will be between 1 mM and 200 mM, preferably between 2 mM and 100 mM.

[0028] It is also an object of the present invention to provide a system that can be inserted in line at the water inlet of a coffee machine and that allows appropriate adjustment of the electrolytic composition of the water used in the coffee extraction step.

[0029] Therefore, in a second aspect, the present invention relates to a system for dynamically adjusting the electrolytic composition of water for an espresso coffee machine, comprising a device for desalting and optionally filtering the water, and a device for adding at least one organic and / or inorganic salt to the demineralized water.

[0030] According to one embodiment, the device for adding at least one organic and / or inorganic salt to demineralized water is a device capable of providing one or more aqueous saline solutions prepared from demineralized water.

[0031] According to one embodiment, the device for adding at least one organic and / or inorganic salt to demineralized water is a device capable of providing the at least one organic and / or inorganic salt to the demineralized water in solid form.

[0032] According to a further embodiment, the device for adding at least one organic and / or inorganic salt to demineralized water is a device that is able to provide the at least one organic and / or inorganic salt to the demineralized water both in solid form and in the form of one or more aqueous saline solutions prepared from the demineralized water.

[0033] Advantageously, the addition is made in proportion to the water flow required by the machine.

[0034] Finally, according to a third aspect, the invention relates to a machine for preparing and dispensing espresso coffee, comprising: The water supply section, a discharge group adapted to cooperate with a port filter (filter holder) having a filter basket with a coffee powder pack; a system for adjusting the electrolytic composition of the water used to prepare espresso coffee; and configured to supply pressurized water to the coffee powder pack to dispense espresso coffee; The system comprises a water demineralizer and an apparatus for adding at least one organic and / or inorganic salt to the demineralized water.

[0035] Preferably, the system according to the invention further comprises a water filtration device.

[0036] According to one embodiment, the device for adding at least one organic and / or inorganic salt to demineralized water is a device capable of providing one or more aqueous saline solutions prepared from demineralized water.

[0037] According to one embodiment, the device for adding at least one organic and / or inorganic salt to demineralized water is a device capable of providing the at least one organic and / or inorganic salt to the demineralized water in solid form.

[0038] According to a further embodiment, the device for adding at least one organic and / or inorganic salt to demineralized water is a device that is able to provide the at least one organic and / or inorganic salt to the demineralized water both in solid form and in the form of one or more aqueous saline solutions prepared from the demineralized water.

[0039] Advantageously, the addition is made in proportion to the water flow required by the machine.

[0040] Alternatively, a fractionator may be provided which receives water upstream of the corrector and supplies the water to the dosing device, so that a portion of the water which has passed through the dosing device and a portion of the water which has not been resalinated are supplied to the machine.

[0041] The fractionator may comprise a proportional valve. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is an exemplary diagram of an espresso coffee machine equipped with a system according to the invention; [Figure 2] 1 is a simplified diagram of a system according to a first embodiment of the present invention; [Figure 3] 2 is a simplified diagram of a system according to a second embodiment of the present invention. [Figure 4] Graph showing the amount (mg / g, vertical axis) of trigonelline (white vertical bars) and caffeine (black vertical bars) extracted at 90° C. (panel a) and 27° C. (panel b). [Figure 5] 1 is a graph showing the variation of the octanol / water partition coefficient (Kow, vertical axis) as a function of temperature (horizontal axis) for caffeine (panel a) and trigonelline (panel b). [Figure 6] Graphs showing the amount of caffeine (mg / g, vertical axis) extracted using fully demineralized ultrapure water (MilliQ) or aqueous solutions of 2-4 mM (panel a) or 50 mM (panel b). [Figure 7]Graphs showing the amount of carbohydrate (mg / g, vertical axis), measured as pectin, extracted using fully demineralized ultrapure water (MilliQ) or aqueous solutions of 2-4 mM (panel a) or 50 mM (panel b). [Figure 8] Graph showing the values ​​(% vertical axis) of specific flavor-imparting substances extracted using aqueous solutions containing sodium ions (panel a), potassium ions (panel b), magnesium ions (panel c), and calcium ions (panel d). DETAILED DESCRIPTION OF THE INVENTION

[0043] The invention will become more fully apparent from the following detailed description, given by way of non-limiting example, read with reference to the accompanying drawings, in which:

[0044] According to the present invention, there is provided a method for treating water used in an espresso coffee machine, aimed at controlling the chemical composition, in particular the electrolytic composition, of the water used in the preparation of espresso coffee, which method provides for the total or partial demineralization and optional filtration of the water, followed by the addition of one or more organic and / or inorganic salts to the water.

[0045] According to the present invention, there is provided a method for controlled extraction of at least one organic molecule present in ground coffee during the preparation of espresso coffee in a machine for preparing and dispensing espresso coffee, said method comprising the steps of: a) at least partially desalting and optionally filtering the water. b) adding at least one organic and / or inorganic salt in a homogeneous mixture to said demineralized water in proportion to the water flow required by the machine. c) preparing espresso coffee using the water thus obtained.

[0046] Preferably, according to the present invention, the desalting and optionally filtering step a) can be carried out by techniques known in the art, such as reverse osmosis, distillation, etc., or by distillation using a Millipore® device. In this way, the water obtained from step a) of the method according to the present invention can be water of various purities, for example type I, type II or type III distilled water. Preferably, the water obtained is type I fully desalted ultrapure water (MilliQ®).

[0047] Subsequently, one or more organic and / or inorganic salts are added to the water in the desired concentrations depending on the sensory characteristics to be imparted to the espresso coffee. According to an embodiment, the salts are added in the form of one or more aqueous saline solutions prepared from demineralized water and containing one or more organic and / or inorganic salts in the appropriate concentrations. Additionally or alternatively, the salts are added in solid form.

[0048] Applicants have discovered that certain organic and inorganic salts can either favor or disadvantage the extraction of different organic molecules contained in ground coffee.

[0049] Table 1 below shows the ability of eight salts commonly present in oligomineral water to extract the most important organic components of coffee.

[0050] The salts are listed for each extracted substance from the extractant with the lowest extraction capacity to the best, i.e. the amount of substance extracted from the ground coffee. The red column indicates the amount of substance extracted using fully demineralized ultrapure water (MilliQ®).

[0051] [Table 1]

[0052] From the data in Table 1, it is possible to identify electrolytes that act as better or worse extractants for each of the test substances (Table 2). It is also important to note that in many cases, the individual ions (e.g., chloride, calcium, etc.) are the primary source of variation, rather than the particular salt used.

[0053] [Table 2]

[0054] By precisely selecting the type and amount of salt dissolved in the water used to prepare espresso coffee, it is possible to control the chemical composition of the resulting beverage and, therefore, its sensory characteristics. Indeed, each of the above substances is characterized by a specific taste (Table 3), and its concentration in the resulting coffee contributes to imparting that particular taste.

[0055] Thus, controlled extraction according to the present invention allows obtaining espresso coffee with specific sensory characteristics (e.g., sourness, sweetness, bitterness, etc.) from the same mixture of ground coffee, details of which are provided in the examples.

[0056] [Table 3]

[0057] The method of the present invention therefore provides a system for adjusting the electrolytic composition of the water supplied to a coffee machine so as to obtain espresso coffee with specific organoleptic characteristics, and this also makes it possible to standardize the performance of the coffee machine in terms of the quality of the coffee obtained, as well as the efficiency and durability of the machine, regardless of the location where the coffee machine is installed, i.e. the quality of the water available from the public water network.

[0058] According to the invention there is also provided a system for adjusting the electrolytic composition of water for an espresso coffee machine, characterized in that it comprises a device for desalting and optionally filtering the water, and a device for adding at least one organic and / or inorganic salt to the demineralized water.

[0059] Finally, according to a third aspect, the invention relates to a machine for preparing and dispensing espresso coffee, comprising: The water supply section, a discharge group adapted to cooperate with a port filter (filter holder) having a filter basket with a coffee powder pack; a system for adjusting the electrolytic composition of water used to prepare espresso coffee, the system being configured to supply pressurized water to the coffee powder pack to dispense espresso coffee; The system comprises a device for desalting and optionally filtering water, and a device for adding at least one organic and / or inorganic salt to the desalted water.

[0060] Figure 1 shows, by way of example only, an espresso coffee machine, generally designated 10. Machine 10 comprises a substantially closed machine body 11 which houses the main components of the machine, some of which are described below. The top of machine 10 preferably comprises a surface 12 on which a cup can be placed. An electrical resistance (not shown) or other heating system may be provided for heating the cup on surface 12.

[0061] The machine 10 comprises at least one dispensing unit 13 for dispensing espresso coffee. Preferably, the machine 10 comprises several dispensing groups 13, for example three groups as in the machine illustrated in Figure 1. There may also be two, four or more groups. Below the dispensing unit 13 there is preferably a drip tray 14, preferably partially closed at the top by a grill 15. Typically, a coffee cup rests on the grill 15 during the dispensing of the espresso coffee.

[0062] A port filter carrying a filter basket for a coffee powder pack can be removably connected to each discharge group 13 .

[0063] The machine 10 may include one or more displays 16 and push buttons, for example, to turn the machine on / off and / or to start / stop a dispensing operation.

[0064] Preferably, the machine 10 shown in Figure 1 also comprises, for each dispense group 13, a lever 18 (or a push button, not shown) for starting / ending the dispense of espresso coffee and / or for varying the dispense pressure during the dispense of espresso coffee.

[0065] Also according to the invention, the machine 10 comprises a system 50 configured to at least partially demineralize and optionally filter the water entering the machine and then add at least one organic and / or inorganic salt to the water used to prepare espresso coffee.

[0066] According to one embodiment of the present invention (FIG. 2), a system 50 comprises a device 30 for desalting and optionally filtering water, and a device 37 for adding at least one organic and / or inorganic salt to the demineralized water. According to a particularly preferred embodiment, the device 37 for adding at least one organic and / or inorganic salt is a device capable of providing one or more aqueous saline solutions prepared from the demineralized water and containing the desired salts in appropriate concentrations. According to another preferred embodiment, the device 37 is a device capable of adding the desired salts in solid form to the demineralized water. According to a further embodiment, the device 37 is a device capable of providing the desired salts to the demineralized water both in solid form and in the form of one or more aqueous saline solutions prepared from the demineralized water.

[0067] 3, downstream of the device for desalting and optionally filtering the water, a fractionator 35 is preferably provided, which supplies the machine with the portion of water that has passed through the dosing device 37 and the portion of water that has not been resalinated. The fractionator can be, for example, a proportional valve 35.

[0068] Preferably, system 50 includes one or more flow measurement devices. For example, a first flow meter 31 may be provided upstream of addition device 37 and a second flow meter 34 may be provided upstream of the fractionator.

[0069] [Experimental Section] The Applicant conducted a series of tests under the machine's actual operating conditions. Each 50 ml sample of espresso coffee was extracted at 92°C and 8 bar pressure using 14 g of ground coffee. Each espresso was filtered, diluted 1:100 with Milli-Q water, and analyzed to determine the concentration of organic molecules commonly present in ground coffee. Such organic molecules of interest were carbohydrates (expressed as pectins), caffeine, trigonelline, caffeic acid, ferulic acid, malic acid, citric acid, nicotinic acid, and melanoidins.

[0070] Five independent analyses were performed for each of the extraction solutions used to determine the concentration of each analyte.

[0071] Applicants have discovered that there is a direct relationship between the electrolytic composition of the water used in the extraction and the concentration of the analyte of interest in the espresso coffee.

[0072] The applicant has also discovered that this relationship can be exploited to obtain coffee extracts with controlled chemical composition and therefore controlled organoleptic properties.

[0073] [Example 1] The first experimental measurements involved the evaluation of the correlation between the type of salt present in the water used to prepare espresso coffee and the concentration in the resulting coffee of some organic molecules commonly present in espresso coffee.

[0074] As a non-limiting example, the results of an experiment in which caffeine and trigonelline were extracted from espresso coffee prepared at different temperatures using water with different ionic compositions are described below.

[0075] Figure 4a shows data on the amount of trigonelline (white bars) and caffeine (black bars) extracted (in mg) per gram of ground coffee used, extracted at 90 °C using water of variable electrolytic composition, i.e., fully demineralized ultrapure water (MilliQ) or water containing calcium chloride (CaCl) or sodium chloride (NaCl) at a concentration of 0.5 M.

[0076] Figure 4b shows the results of the same experiment carried out at 27°C.

[0077] From the analysis of the two figures, it is clear that the water extraction capacity varies with both variations in the electrolyte composition and variations in temperature, and that this effect is different for the two molecules analyzed.

[0078] This is due to variations in the relative affinities of such molecules for the two matrices (ground coffee and water), which variations are specific to each molecule analyzed.

[0079] Indeed, the temperature dependence of the octanol-water partition coefficient (Kow), a parameter that indicates the relative affinity of a substance for the organic and polar phases, was experimentally determined for both caffeine (Panel a) and trigonelline (Panel b, Figure 5). As a result, Kow changed with temperature and showed different trends for the two substances.

[0080] [Example 2] Thus, the variation in the extraction capacity of the water was then studied with respect to molecules commonly found in ground coffee as a function of the type and concentration of salts contained in the water used.

[0081] As a non-limiting example, the results of extraction experiments of caffeine and carbohydrates expressed as pectin carried out at temperatures between 90 and 93°C are set forth below.

[0082] The analytical methods used are listed in Table 4 below.

[0083] [Table 4]

[0084] Figures 6a-b show the amount of caffeine (in mg) per gram of ground coffee used, extracted using fully demineralized ultrapure water (MilliQ) or 2-4 mm (Figure 6a) or 50 mm (Figure 6b) aqueous solutions of potassium chloride, sodium chloride, magnesium chloride, calcium chloride, potassium sulfate, potassium nitrate, calcium sulfate, or magnesium sulfate.

[0085] Figure 7a-b shows the results of a similar experiment with carbohydrates.

[0086] The above results therefore show that there is a positive correlation between the electrolytic composition of the water used to prepare espresso coffee and the chemical composition of the resulting coffee, which, as is known, is directly related to the sensory properties of the beverage.

[0087] Therefore, experiments have been carried out which have led to the conclusion that by controlling the electrolytic composition of the water used to prepare espresso coffee it is possible to control the organoleptic properties of the resulting beverage.

[0088] [Example 3] Four different espressos were prepared from the same ground coffee powder, but treated according to the method of the present invention, using water containing sodium, potassium, magnesium or calcium ions at concentrations ranging from 2 to 4 mM.

[0089] Based on the extraction capacity of each of these ions, it is possible to predict the sensory characteristics of the espresso coffee obtained with each brine. Graphs A-C in Figure 8 show the values ​​of given flavor imparting substances as percentage scores, with the maximum value on the scale corresponding to maximum extraction.

[0090] Observing the graphs, it can therefore be seen that the espresso coffee obtained from water containing 2 mM sodium ions (graph A) is characterized mainly by bitterness and roasted / caramelized notes, that obtained from water containing 2 mM potassium (graph B) is characterized mainly by sweetness and acidity, that obtained from water containing 2.5 mM magnesium ions (graph C) is characterized by an intense aroma and a good balance between sweetness and bitterness, and that obtained from water containing 4 mM calcium ions (graph D) is characterized by sweetness and significant acidity.

[0091] Espresso prepared with salt solutions ranging from 0.002M to 0.004M was tasted by nine tasters, and their judgments are shown in Table 5 below. The agreement between the experimental data and the tasters' judgments was very high, with almost perfect agreement when considering bitterness and acidity together. In fact, it is difficult to distinguish these two flavors from a taste perspective.

[0092] [Table 5]

Claims

1. A coffee machine (10) for preparing and dispensing espresso coffee, said machine comprising: A water supply section (IN), a discharge group (13) adapted to cooperate with a port filter having a filter basket with a coffee powder pack; a system (50) for adjusting the electrolytic composition of water used to prepare espresso coffee, the system being configured to supply pressurized water to the coffee powder pack to expel espresso coffee; The system comprises a water demineralizer (30) and a device (37) for adding at least one inorganic salt to the demineralized water, Coffee machine (10), wherein the device (37) for adding at least one inorganic salt is a device for providing one or more aqueous saline solutions prepared from demineralized water.

2. Coffee machine (10) according to claim 1, wherein the system (50) further comprises a water filtration device (30).

3. Coffee machine (10) according to claim 1 or 2, wherein the system (50) further comprises a fractionator (35).

4. 1. A method for adjusting the electrolytic composition of water used in the preparation of espresso coffee in an espresso coffee preparation and delivery machine (10) for controlled extraction of at least one organic molecule present in ground coffee, the method comprising: a) desalination of water (30); b) adding at least one inorganic salt to the demineralized water (37); c) preparing espresso coffee using the water thus obtained, The method of claim 1, wherein the at least one inorganic salt is added in step b) in the form of one or more aqueous saline solutions prepared from demineralized water.

5. 5. The method of claim 4, wherein the at least one inorganic salt is also added in solid form in step b).

6. The method of claim 4 further comprising the step of filtering the water (30).

7. The method according to any one of claims 4 to 6, wherein the adding in step (b) is carried out with homogeneous mixing.

8. 7. The method according to any one of claims 4 to 6, wherein the addition in step (b) is made in proportion to the water flow rate required by the coffee machine.

9. The method according to any one of claims 4 to 6, wherein the desalting in step (a) is total or partial.

10. The method according to any one of claims 4 to 6, wherein the inorganic salt is selected from the group comprising sodium, potassium, magnesium and calcium salts.

11. 11. The method of claim 10, wherein the inorganic salt is selected from the group comprising potassium chloride, sodium chloride, magnesium chloride, calcium chloride, potassium sulfate, potassium nitrate, calcium sulfate and magnesium sulfate.

12. A system (50) for adjusting the electrolytic composition of water for an espresso machine (10) comprises a device (30) for desalination of water and a device (37) for adding at least one inorganic salt to the desalinated water, the device (37) for adding the at least one inorganic salt being a device for providing one or more aqueous saline solutions prepared from the desalinated water.

13. The system of claim 12, further comprising a water filtration device (30).

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