instant coffee powder

Abstract

The present invention relates to an instant coffee powder having a closed porosity of 15% to 50%, or 20% to 35%, or 25% to 34%, or 30 to 34%, or about 30%, and to the use of gas hydrates for producing instant coffee powder, and to a method for producing instant coffee powder.

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to instant coffee powder and the use of gas hydrates to produce instant coffee powder.

[0002] [Background technology] Unlike coffee beverages prepared from roast and ground coffee, coffee beverages prepared from instant coffee powders typically do not exhibit a fine foam (crema) on the surface when reconstituted with hot water.

[0003] This foam is known to have a positive impact on the mouthfeel of the product when consumed and is therefore highly desired by many consumers. Additionally, foam acts to retain more of the volatile aromas within the beverage so that they can be perceived by the consumer rather than being dispersed into the surrounding environment.

[0004] The foamed liquid surface of beverages prepared from roast and ground coffee is typically produced by brewing with pressurized water and / or steam. However, in the case of instant coffee powder, the foam must be generated by reconstituting the instant coffee powder with water. Thus, to obtain the foam, gas must be trapped within the instant coffee powder and released by pouring hot water over the powder.

[0005] Numerous methods for preparing foaming instant coffee powders have been reported (e.g., EP 2100514, EP 2689668, EP 2217086, and U.S. Patent Application Publication No. 2013 / 0230628). However, many foaming instant coffee powders are still deficient in that the foam initially produced is not maintained during consumption, or the structure is coarse rather than the fine, smooth foam (crema) ultimately desired by consumers. In addition, the foam (and / or crema) produced is often insufficient.

[0006] Furthermore, current methods for preparing foamable instant coffee powders typically require energetically demanding mixing and freezing units necessary to homogenize gas into viscous liquids and pre-freeze them for freeze-drying, which also typically require high amounts of gas and long gas delivery times.

[0007] Therefore, there is a need for improved foamable instant coffee powders and improved methods of producing foamable instant coffee powders.

[0008] [Summary of the Invention] The inventors have surprisingly found that gas hydrates (also known as clathrate hydrates) can be used to produce instant coffee powder. The inventors have surprisingly found that instant coffee powder produced using the gas hydrates is capable of forming foam and / or crema on its surface when reconstituted with water.

[0009] The inventors have surprisingly found that the use of gas hydrates in the production of instant coffee powder requires less energy-intensive mixing and freezing units, lower amounts of gas, and shorter gas application times than current methods. For example, the use of gas hydrates allows for the gasification of highly viscous coffee solutions (e.g., 60-63% by weight coffee solids).

[0010] The present inventors have surprisingly found that CO2 hydrate can be used to produce an instant coffee powder that forms a crema on the surface when reconstituted with water.

[0011] Thus, in one aspect, the present invention provides a use of a gas hydrate for gasifying a food product. The gas may be air and / or may comprise one or more of carbon dioxide, nitrogen, nitrous oxide, and argon, preferably carbon dioxide and / or nitrogen. Preferably, the food product is coffee and / or a coffee solution.

[0012] According to another aspect, the present invention provides the use of a gas hydrate for producing instant coffee powder, wherein the gas may be air and / or may comprise one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably carbon dioxide and / or nitrogen.

[0013] According to another aspect, the present invention provides a method of producing a coffee slurry containing gas hydrates, comprising the steps of: (a) providing a first coffee solution; (b) cooling the first coffee solution; (c) pressurizing the first coffee solution with a gas, the gas being air and / or comprising one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably carbon dioxide and / or nitrogen, to provide a coffee slurry comprising gas hydrates; Includes:

[0014] In some embodiments, the first coffee solution is cooled in step (b) to between -10°C and 10°C, or between -8°C and 7°C, or between -5°C and 5°C, or to above about 5°C, and / or the gas pressure in step (c) is between 10 and 300 bar, or between 10 and 150 bar, or between 10 and 100 bar, or between 10 and 50 bar, or between 15 and 40 bar, or between 15 and 35 bar, or between 15 and 30 bar (depending on the weight % of coffee solids in the coffee solution and the identity of the gas). In some embodiments, the method comprises, in step (b), cooling the first coffee solution to 0-5°C, or to about 3°C, and in step (c), pressurizing the first coffee solution with carbon dioxide, preferably to 15-25 bar, or to about 20 bar, followed by pressurizing with nitrogen, preferably to 30-300 bar, 30-150 bar, 30-100 bar, 30-50 bar, 30-40 bar, or to about 35 bar.

[0015] In some embodiments, the method further comprises dispersing a gas hydrate in the coffee slurry.

[0016] According to another aspect, the present invention provides a coffee slurry comprising gas hydrate, wherein the gas is air and / or comprises one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably carbon dioxide and / or nitrogen. The coffee slurry can be obtained by the method described above.

[0017] In some embodiments, the first coffee solution and / or coffee slurry comprises between 10% and 50%, between 20% and 40%, or about 30% coffee solids by weight.

[0018] In some embodiments, the coffee slurry has a viscosity of between 10 mPas and 1 Pas at a coffee solids content of between 10% and 50% by weight.

[0019] In some embodiments, the coffee slurry has a viscosity of 10-100 mPas, or 20-100 mPas, or 30-65 mPas, or about 30 mPas or more and / or about 100 mPas or less. The viscosity of the coffee slurry may be higher than the viscosity of the first coffee solution provided in step (a).

[0020] In some embodiments, the coffee slurry preferably comprises 0.5-5 mol / L, 1-5 mol / L, 1-2 mol / L, about 1 mol / L, or about 1.6 mol / L carbon dioxide, and / or preferably 0.01-0.5 mol / L, 0.02-0.1 mol / L, or about 0.05 mol / L nitrogen. In some embodiments, the coffee slurry has a ratio of gas in the hydrate fraction to gas in the liquid fraction (H:L) of 1:1 to 5:1, preferably 2:1 to 3:1.

[0021] In some embodiments, the coffee slurry comprises 0.5-5 mol / L carbon dioxide, or 1-5 mol / L carbon dioxide, or 1-2 mol / L carbon dioxide, or about 1 mol / L carbon dioxide, or about 1.6 mol / L carbon dioxide, and 0.01-0.5 mol / L nitrogen, or 0.02-0.1 mol / L nitrogen, or about 0.05 mol / L nitrogen. In some embodiments, the coffee slurry has a ratio of gas in the hydrate fraction to gas in the liquid fraction (H:L) of 1:1 to 5:1, preferably 2:1 to 3:1.

[0022] In some embodiments, the coffee slurry comprises 0.5-5 mol / L carbon dioxide, or 1-5 mol / L carbon dioxide, or 1-2 mol / L carbon dioxide, or about 1 mol / L carbon dioxide, or about 1.6 mol / L carbon dioxide, or 0.01-0.5 mol / L nitrogen, or 0.02-0.1 mol / L nitrogen, or about 0.05 mol / L nitrogen. In some embodiments, the coffee slurry has a ratio of gas in the hydrate fraction to gas in the liquid fraction (H:L) of 1:1 to 5:1, preferably 2:1 to 3:1.

[0023] According to another aspect, the present invention provides a method for producing instant coffee powder, the method comprising: (a) mixing a coffee slurry containing gas hydrate with a second coffee solution to provide a coffee slurry / coffee solution mix; (b) releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix to provide a foamed coffee solution; (c) drying the foamed coffee solution, preferably by freeze-drying, to provide dried coffee; (d) grinding the dried coffee to provide an instant coffee powder.

[0024] In some embodiments, the coffee slurry is obtained by the method described above or is a coffee slurry comprising gas hydrates described above.

[0025] In some embodiments, the second coffee solution comprises between 10% and 70% by weight, between 30% and 70% by weight, between 50% and 70% by weight, between 55% and 65% by weight, between 60% and 65% by weight, or about 60% by weight of coffee solids.

[0026] In some embodiments, the coffee slurry is added to the second coffee solution under substantially isobaric and isothermal conditions, preferably at a temperature of -10°C to 10°C, or -8°C to 7°C, or -5°C to 5°C, or about -5°C or above, and / or a gas pressure of 10 to 300 bar, or 10 to 150 bar, or 10 to 100 bar, or 10 to 50 bar, or 15 to 40 bar, or 15 to 35 bar, or 15 to 30 bar (depending on the weight % of coffee solids in the coffee solution and the identity of the gas).

[0027] In some embodiments, in the step of releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix, the pressure is released to between 1 bar and 10 bar, or between 5 bar and 10 bar, and / or the temperature of the coffee slurry / coffee solution mix is ​​increased to between -5°C and 10°C, or above 0°C, or to about 5°C, or above 10°C. The method may comprise the additional step of flash-freezing the foamed coffee solution before drying it.

[0028] In some embodiments, the coffee slurry reaches an overrun of 50-500%, or 200-400%, or 250-350%, or about 300%.

[0029] According to another aspect, the present invention provides an instant coffee powder obtained by the above method.

[0030] According to another aspect, the present invention provides an instant coffee powder having a closed porosity of 15% to 50%, or 20% to 35%, or 25% to 34%, or 30% to 34%, or about 30% and / or a foaming porosity of 25% to 34%, or 30% to 34%, or about 30%.

[0031] In some embodiments, the instant coffee powder has a bimodal closed pore distribution. The bimodal pore distribution may include (i) pores having an average diameter of 20 to 100 micrometers, or 20 to 45 micrometers, or about 40 micrometers, and (ii) pores having an average diameter of less than about 20 micrometers, or 1 to less than 20 micrometers, or 1 to 18 micrometers, or 1 to 15 micrometers, or 1 to 10 micrometers, or 2 to 5 micrometers. In some embodiments, (i) contributes 10 to 99% of the total pore volume, and / or (ii) contributes 1 to 90% by volume of the total pore volume, and / or (i) contributes 10 to 90% by number of the total pores, and / or (ii) contributes 10 to 90% by number of the total pores. The larger pores may consist substantially of open pores, and / or the smaller pores may consist substantially of closed pores. [Brief explanation of the drawings]

[0032] [Figure 1] This is a flowchart showing the basic steps in making instant soluble coffee. The scheme is adapted from Bhandari, B., N. Bansal, M. Zhang, and P. Schuck: Handbook of Food Powders: Processes and Properties. Elsevier Science, 2013. The sketch illustrates the processing steps for instant coffee powder. In the extraction process, ground coffee is extracted with water to a solids content of 20-30% by weight. The extracted coffee is then concentrated under pressure and high temperature into a viscous slurry with a solids content of 40-50% by weight. CO₂ and N₂ are typically added to control the density of the medium for further drying (Clarke, 2003, Coffee Instant, Encyclopedia of Food Sciences and Nutrition, pp. 1493-1498). The present invention provides a method for foaming a concentrated coffee solution with gas hydrate. The foamed coffee solution is then dried in a dehydration process. [Figure 2]Solubility curves of CO2 in coffee solutions. Solubility curves of CO2 in 30 wt% and 50 wt% coffee solutions at 4°C and 10°C from the current study, and solubility curves of CO2 for 20 wt% coffee solution at 80°C and 120°C from Wilken, M., K. Fischer, and I. Meier: Experimental Determination of Carbon Dioxide Solubility in 20 mass percent Coffee Aqueous Solution at 80 and 20°C and Pressures up to 30 bar. Technical report, University of Oldenburg, Oldenburg, 1999. A polynomial was fitted to the data points to obtain a positive correlation between pressure and solubility. [Figure 3A] Gas hydrate phase diagram for coffee systems. Phase diagram for CO2 hydrate coffee systems compared with thermodynamic models for pure water-CO2 and pure 25 wt% and 50 wt% model sugar solutions-CO2 systems. Experimental gas hydration points by T-cycle heating / cooling and high-pressure DSC (performed on 30 wt% coffee solution) lie between pure water and 25 wt% sugar solution. Therefore, the 25 wt% sugar solution can serve as a model system for the 30 wt% coffee solution. [Figure 3B] (b) CO2 / N2 water phase diagram from Kang, SP, et al., 2001. The Journal of Chemical Thermodynamics, 33(5), pp. 513-521. The numbers in the graph indicate the CO2 composition ratio. [Figure 4A] Rheological properties of coffee solutions without gas hydrate. In (a), flow curve profiles of viscosity versus shear rate show Newtonian behavior for 30 wt%, 40 wt%, 50 wt%, and 60 wt% coffee solutions. Only the downward shear rate gradient is shown. [Figure 4B]Rheological properties of coffee solutions without gas hydrate. In (b), the viscosity dependence on temperature is shown for 30 wt%, 40 wt%, 50 wt%, and 60 wt% coffee solutions. Only the downward slope is depicted; the upward slope was similar to that plotted. [Figure 5] High-pressure CLAG (clathrate hydrate slurry generator) reactor process variables from experiments to prepare effervescent media for different pumping tests. Coffee slurry generation process variables: viscosity, density, pressure, and temperature over time. Coffee slurries containing CO2-containing gas hydrates (labeled CO2H for descriptive purposes), CO2- and N2-containing gas hydrates (labeled CO2:N2=0.54 for descriptive purposes), and gas-saturated coffee solutions (labeled CO2-dissolved and N2-dissolved) were formed in the CLAG reactor. All experiments were formed from 30 wt% coffee solutions. The induction time (first appearance of gas hydrates) is labeled on the time axis. The abbreviations diss and H stand for dissolved and hydrate, respectively. [Figure 6A] 1 is a process variable profile during coffee slurry delivery. [Figure 6B] Figure 1. Process variable profile during coffee slurry transfer. (a) The manipulated variable profile during transfer of 30% coffee CO2 hydrate slurry compared to dissolved nitrogen in 30 wt% coffee slurry transferred into 60 wt% coffee concentrate in (b). As material from the loop is fed into the EGLI line, the pressure in the loop decreases. Loop: refers to the CLAG side stream (i.e., coffee slurry). Main: refers to the EGLI, main stream. Tin = inlet temperature. Tin = Tloop, i.e., isothermal transfer, T>0°C. T2 = temperature between scraped surface heat exchangers 1 and 2. Tout = outlet temperature. [Figure 7A] Reconstituted ground and sieved instant coffee powders and their properties. [Figure 7B]Reconstituted ground and sieved instant coffee powders and their properties. (a) Sample made by infusing 30 wt% coffee CO2 hydrate slurry, and (b) sample made by infusing 30 wt% coffee-mixed CO2 / N2 hydrate slurry with CO2 / N2 ratios of 0.54 and 0.48, respectively. Closed porosity (CP) and overrun (OR) are shown below the reconstituted instant coffee powder images. [Figure 8] Scanning electron microscopy. Scanning electron microscopy of granules from a reference instant coffee powder (made with nitrogen gas) producing crema was compared with scanning electron microscopy of granules from an instant coffee powder according to the invention (made with CO / N gas hydrate). [Figure 9] Cryo-scanning electron microscopy images of the microstructure of a frozen foamed coffee solution sample before freeze-drying. The sample was acquired at 2000x and 250x magnification and an accelerating voltage of 2 kV. [Figure 10]1 is a schematic diagram of a method for producing instant coffee powder according to the present invention, the method comprising the steps of: (a) providing a first coffee solution; (b) cooling the first coffee solution; (c) pressurizing the first coffee solution with a gas to provide a coffee slurry (side stream) comprising gas hydrates, preferably the gas is air and / or comprises one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably the gas comprises carbon dioxide and / or nitrogen; (d) mixing the gas hydrate-containing coffee slurry (side stream) with a second coffee solution (main stream) to provide a coffee slurry / coffee solution mix; (e) releasing the pressure on the coffee slurry / coffee solution mix to provide a foamed coffee solution; (f) rapidly freezing the foamed coffee solution to provide a stabilized foamed coffee solution (e.g. in a solid coffee block format); and (g) drying, preferably freeze-drying, the stabilized foamed coffee solution to provide dried coffee (e.g. in a dry solid coffee block format). (h) grinding the dried coffee to provide an instant coffee powder.

[0033] [Mode for Carrying Out the Invention] Gas hydrate "Gas hydrates," also known as clathrate hydrates or water clathrates, are crystalline water-based solids that physically resemble ice, in which gas is trapped inside a 3D "cage" of hydrogen-bonded water molecules.

[0034] Most low molecular weight gases, including O, H, N, N0, CO, CH, H2S, Ar, Kr, Ne, He, and Xe, form hydrates at suitable temperatures and pressures. Gas hydrates can be formed by providing a suitable gas and lowering the temperature and / or increasing the gas pressure of a suitable solution (e.g., coffee extract solution).

[0035] The identity of the gas is not particularly limited. Any gas suitable for producing instant coffee powder and / or for use in industrial food processes may be used. For example, the gas may be air and / or may include one or more of carbon dioxide, nitrogen, nitrous oxide, and argon. In preferred embodiments, the gas includes carbon dioxide and / or nitrogen. In some embodiments, the gas hydrate includes substantially the same gas. In some embodiments, the gas is a pure gas (e.g., 99% or more, or 99.9% or more, or 100% a single gas). In preferred embodiments, the gas hydrate is CO2 or N2 hydrate.

[0036] Suitable temperatures and gas pressures vary depending on the gas and food product. For example, CO2 hydrate can be formed in a 30 wt% coffee solution at about 6°C and about 30 bar, or in a 50 wt% coffee solution at about 4°C and about 30 bar. The lower the temperature of the solution, the lower the gas pressure required, and vice versa; the higher the temperature of the solution, the higher the gas pressure required. For example, CO2 hydrate can be formed in a 30 wt% coffee solution at about 6°C and about 30 bar, or at about -4°C and about 10 bar. Conditions under which ice forms and / or gas condenses may need to be avoided. The freezing point depression (i.e., the temperature at which pure ice forms) depends on the weight percent of coffee solids in the coffee solution. Gas hydrates can form under these conditions, but they are complex to process and may form blockages. For example, temperatures lower than -4°C should not be used to form gas hydrate in a 30% by weight coffee solution, since -4°C is approximately the freezing point depression for that solution. For example, the second quadruple point (the point where liquid, hydrate, vapor, and condensed gas phases converge) for CO2 in a 30% by weight coffee solution is approximately 8-10°C and 44 bar. Therefore, CO2 becomes liquid at lower temperatures and / or higher pressures. Temperature and gas pressure can be varied depending on the desired viscosity and / or desired gas concentration.

[0037] Thus, the temperature and pressure required to form gas hydrates are interdependent and will vary depending on the gas and solution (e.g., the weight percent solids in a coffee solution). Exemplary conditions for forming CO hydrate in a 30 wt. % coffee solution are −3 to 7.8°C and 10 to 38 bar, or about 10 bar or higher. Exemplary conditions for forming N hydrate in a 30 wt. % coffee solution are −2.5 to 5.5°C and 140 to 285 bar. Exemplary conditions for forming N O hydrate in a 30 wt. % coffee solution are about 0 to 9°C and 12 to 28 bar. To form hydrates at lower pressures, lower temperatures must be used.

[0038] In some embodiments, a gas hydrate is formed with a first gas before introducing one or more additional gases. Thus, the final gas hydrate can contain two or more gases; i.e., the gas hydrate can be a mixed gas hydrate. For example, in a mixed CO2 / N2 hydrate, N2 can be embedded under low pressure by leaving small hydrate cages unoccupied by CO2. CO2 hydrate can be first prepared at a lower pressure, and then N2 can be added at a higher pressure. A similar method can be used for any combination of suitable gases. In a preferred embodiment, the gas hydrate is a mixed CO2 / N2 hydrate. The mole fraction of CO2 captured in the CO2 / N2 hydrate can be 0.1-0.99, or 0.5-0.99, or 0.8-0.99, or 0.9-0.99, or 0.95-0.99, or about 0.97. In other embodiments, the gas hydrate is N2O / N2 hydrate (Yang, Y., et al., 2017. Environmental science & technology, 51(6), pp. 3550-3557) or N2O / CO2 hydrate or N2O / CO2 / N2 hydrate.

[0039] In a preferred embodiment, CO hydrate (or alternatively, N O or CO / N O hydrate) is formed prior to the introduction of nitrogen gas. For example, CO hydrate can be formed with carbon dioxide introduced at 10-50 bar, 15-25 bar, or about 20 bar and −3 to 7.8° C. or about 2° C. (e.g., 1-2° C. and 20-30 bar, or above about 20 bar). After a small amount of CO hydrate has formed (indicated by a pressure drop), nitrogen can be introduced to increase the total gas pressure. The amount of nitrogen introduced (i.e., the CO:N ratio) and the pressure required will vary depending on the desired ratio of CO / N in the gas hydrate. The total gas pressure can be increased to 10-300 bar, 10-200 bar, 20-300 bar, 20-200 bar, 20-100 bar, 20-50 bar, 30-40 bar, or about 35 bar at -5°C to 5°C, 0-5°C, or about 2°C (compare Kang, SP, et al., 2001, The Journal of Chemical Thermodynamics, 33(5), pp. 513-521). The mole fraction of CO2 (in the final gas mix) to form mixed CO2 / N2 hydrate can be 0.1-0.9, 0.2-0.8, 0.4-0.6, 0.47-0.54, or about 0.54. The fraction of CO2 (in the final gas mix) should be such that CO2 does not condense. CO2 will condense over a wide range of pressure and temperature conditions, depending on its vapor pressure. For example, CO2 condenses in a 30 wt% coffee solution at approximately 8-10°C and 44 bar.

[0040] As noted above, the temperature and pressure required to form gas hydrates are interdependent and vary depending on the gas and solution (e.g., the weight percent solids in a coffee solution). Exemplary conditions for forming a mixed CO2 / N2 hydrate in a 30 wt% coffee solution are a CO2 mole fraction of about 0.54 in the gas mixture, with CO2 introduced at about 20 bar and 0-5°C or about 2°C before N2 is introduced to reach a total gas pressure of 35 bar. If a higher amount of N2 is desired in the mixed hydrate, a lower mole fraction of CO2 can be used in combination with a higher pressure (and / or lower temperature); for example, a CO2 mole fraction of about 0.1 and a pressure of about 100-130 bar at approximately 0°C can be used to form a CO2 / N2 hydrate with a higher amount of N2 (see Figure 3b).

[0041] The gas hydrates can be decomposed by increasing the temperature and / or decreasing the pressure. Preferably, the gas hydrates can be decomposed by increasing the temperature and decreasing the pressure, or by decreasing the pressure alone. As a result, gas hydrates may not be present in the foamed food product (e.g., coffee) prior to drying. For example, gas hydrates may not be present in foamed coffee solutions, stabilized foamed coffee solutions, dried coffee, or instant coffee powder.

[0042] Use of gas hydrates to gasify food products In one aspect, the present invention provides a use of a gas hydrate for gasifying a food product. The gas may be air and / or may comprise one or more of carbon dioxide, nitrogen, nitrous oxide, and argon, preferably carbon dioxide and / or nitrogen. In preferred embodiments, the food product has a viscosity of 100 mPas to 10 Pas, or 500 mPas to 10 Pas, or 1 Pas to 10 Pas, and 1 Pas to 5 Pas.

[0043] Food products include, for example, liquid products (e.g., ready-to-drink products, ready-to-heat products, liquid concentrates, beverages) such as coffee, coffee chicory, coffee-cereal-chicory mixtures, cocoa, tea, nutritional drinks, toppings, desserts, sauces, and soups; powder products such as instant coffee powder, instant cocoa powder, instant tea powder, nutritional drink powder, instant topping powder, instant dessert powder, instant sauce powder, instant soup powder, bread mix, cake mix, pastry mix, waffle mix, and pizza crust mix; and frozen products. Preferably, the food product is coffee, coffee solution, and / or instant coffee powder.

[0044] The present invention provides a method for whipping a food product, the method comprising: (a) forming a gas hydrate in a first portion of a food product to provide a food product slurry containing the gas hydrate; (b) mixing the food product slurry containing the gas hydrate with a second portion of the food product to provide a food product slurry / food product mix; (c) releasing the pressure and / or increasing the temperature of the food product slurry / food product mix to provide a foamed food product.

[0045] Preferably, the first portion of the food product is 1 to 20% by volume, or 2 to 15% by volume, or 5 to 15% by volume, or 5 to 10% by volume of the food product, and the second portion of the food product is the remainder of the food product.

[0046] The gas may be air and / or may comprise one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably carbon dioxide and / or nitrogen. Preferably, the food product is a coffee solution.

[0047] In preferred embodiments, the food product has a viscosity of 100 mPas to 10 Pas, or 500 mPas to 10 Pas, or 1 Pas to 10 Pas, and 1 Pas to 5 Pas. The viscosity can be measured by any method known to those skilled in the art, for example by a rheometer. Preferably, the viscosity is less than 100 mPas. -1 The measurements are carried out at a shear rate of 1000 rpm and a temperature of 7°C.

[0048] Advantageously, incorporating the gas into a food product in solid form (e.g., into a food product that includes a gas hydrate) facilitates the incorporation of the gas into the food product and / or reduces the time required to gasify the food product and / or reduces the energy required to gasify the food product.

[0049] Coffee slurry containing gas hydrate A "coffee solution" according to the present invention is a solution containing soluble coffee components. The coffee solution may also contain non-soluble coffee components and / or other non-coffee components, and / or such components in suspension. A "coffee slurry" according to the present invention is a coffee solution containing dispersed gas hydrates.

[0050] The coffee solution for use in the present invention may be extracted from roasted coffee beans or coffee grounds. The roasted coffee beans or coffee grounds may be extracted by any method known to those skilled in the art, such as hot water extraction, vacuum evaporation, centrifugal concentration, or freeze concentration (Bhandari et al. 2013 Handbook of Food powders; processes and properties). Thus, the coffee solution may be a coffee extract.

[0051] The present invention provides a method for producing a coffee slurry containing gas hydrates, the method comprising: (a) providing a first coffee solution; (b) cooling the first coffee solution; (c) pressurizing the first coffee solution with a gas to provide a coffee slurry comprising gas hydrates, the gas comprising air and / or one or more of carbon dioxide, nitrogen, nitrous oxide, and argon, preferably carbon dioxide and / or nitrogen; Includes:

[0052] The method may further comprise the step of dispersing gas hydrates in the coffee slurry. The gas hydrates may be dispersed during and / or after formation. Preferably, the gas hydrates are dispersed by mixing the coffee slurry, for example by mixing using a rotating device that provides mixing, a static mixer or a pin mixer. The gas hydrates may be mixed in a scraped surface heat exchanger (SSHE) and / or through pumping action.

[0053] The first coffee solution can be any suitable coffee solution, for example, a coffee solution suitable for producing instant coffee powder. Preferably, the first coffee solution contains 10% to 50%, 20% to 40%, 25% to 35%, 30% to 35%, or about 30% by weight of coffee solids. Preferably, the first coffee solution has a viscosity of 10 mPas to 10 Pas, or 10 mPas to 2.5 Pas, or 10 mPas to 1 Pas, or 10 mPas to 100 mPas, or 20 to 100 mPas, or 20 mPas to 60 mPas, or about 20 mPas or more and / or about 100 mPas or less. The viscosity depends on the weight percent of coffee solids, i.e., a higher weight percent will result in a higher viscosity (see Figure 4). For example, a 60% by weight coffee solution will have a viscosity of 10 mPas to 10 Pas at 30 bar, 7°C, and 100°C. -1 At a shear rate of 100 s, a 30 wt. % coffee solution may have a viscosity of approximately 2.3 Pas, while a 30 wt. % coffee solution may have a viscosity of approximately 2.3 Pas at 30 bar, 7°C and 100 s -1The viscosity may be approximately 10-20 mPas at a shear rate of 100 s. The viscosity is also temperature dependent, with lower temperatures resulting in higher viscosities. Viscosity may be measured by any method known to those skilled in the art, such as by a rheometer. For example, the viscosity may be measured at a shear rate of 100 s for a coffee solution that does not contain gas hydrates. -1 and a temperature of 7°C.

[0054] The temperature and pressure required to form gas hydrate are interdependent and vary depending on the gas and solution (e.g., the weight percent solids in the coffee solution). For example, Figure 3 provides a phase diagram for forming CO2 hydrate in 30 wt% and 50 wt% coffee solutions. Conditions under which ice forms and / or the gas condenses may need to be avoided. The freezing point depression depends on the weight percent coffee solids in the coffee solution. For example, a 30 wt% coffee solution has a freezing point temperature of approximately -4°C, and a 60 wt% coffee solution has a freezing point of approximately -16°C.

[0055] For example, the coffee solution can be cooled in step (b) to -15°C to 15°C, or -10°C to 12°C, or -10°C to 10°C, or -10°C to 8°C, or -8°C to 7°C, or -5°C to 5°C, or to about -7°C, -5°C, or -4°C or higher, depending on the gas, coffee solution, and gas pressure. The gas pressure in step (c) can be 10 to 500 bar, 10 to 300 bar, 10 to 200 bar, 10 to 150 bar, 10 to 100 bar, 10 to 50 bar, 15 to 40 bar, 15 to 35 bar, or 15 to 30 bar, depending on the gas, coffee solution, and temperature. Preferably, if CO2 hydrate is desired, a 30 wt% coffee solution is cooled to -3 to 7.8°C and 10 to 38 bar, or to about 10 bar or higher. Preferably, if N hydrate is desired, a 30 wt % coffee solution is cooled to about -2.5°C to 5.5°C and pressurized to 140 to 285 bar with N . Preferably, if N O hydrate is desired, a 30 wt % coffee solution is cooled to about 0 to 9°C and pressurized to 12 to 28 bar with N . To form hydrate at lower pressures, lower temperatures must be used. Preferably, if a CO / N mixed hydrate is desired, a first coffee solution is cooled to about -3 to 2°C, pressurized to about 20 bar with CO , and then pressurized to about 35 bar with N (and a mole fraction of CO of about 0.54). Alternatively, if a CO2 / N2 mixed hydrate with a large amount of N2 is desired, the first coffee solution is cooled to about -3 to 2°C, pressurized to about 20 bar with CO2, and then pressurized to about 100 to 300 bar with N2 (to achieve a CO2 mole fraction of about 0.1 or less).

[0056] A coffee slurry containing a gas hydrate according to the present invention may contain 10% to 50%, 20% to 40%, 25% to 35%, 30% to 35%, or about 30% by weight of coffee solids. For example, the coffee slurry may be produced from a first coffee solution containing 10% to 50%, 20% to 40%, 25% to 35%, 30% to 35%, or about 30% by weight of coffee solids.

[0057] The coffee slurry containing gas hydrates may have a viscosity of 10 mPas to 100 mPas, or 20 to 100 mPas, or 20 to 60 mPas, or about 20 mPas or more and / or about 100 mPas or less. The viscosity of the coffee solution increases due to the formation of gas hydrates. Therefore, the formation of gas hydrates can be monitored by measuring the viscosity of the coffee slurry. Preferably, the viscosity of the coffee slurry is higher than the coffee solution provided in step (a), for example, 2 to 4 times higher. The viscosity can be measured by any method known to those skilled in the art, for example, by a rheometer or flowmeter. For example, the viscosity can be measured at 100 s for the coffee slurry containing gas hydrates. -1 and a temperature of 1°C.

[0058] The coffee slurry may contain one or more of carbon dioxide, nitrogen, nitrous oxide, and argon, preferably carbon dioxide and / or nitrogen. The coffee slurry may contain 0.01-7.5 mol / L, 0.1-7.5 mol / L, 1-5 mol / L, 1-2 mol / L, or about 1.5 mol / L of gas. In some preferred embodiments, the coffee slurry preferably contains 0.5-5 mol / L, 1-5 mol / L, 1-2 mol / L, or about 1.6 mol / L of carbon dioxide. In some other preferred embodiments, the coffee slurry preferably contains 0.5-5 mol / L, 0.5-2 mol / L, or about 1 mol / L of carbon dioxide and preferably 0.01-5 mol / L, 0.01-2 mol / L, 0.01-1 mol / L, 0.01-0.5 mol / L, 0.02-0.1 mol / L, or about 0.05 mol / L of nitrogen. The amount of gas refers to the total amount of gas in the coffee slurry, i.e. the total amount of gas in both the hydrate fraction and the liquid fraction. The amount of gas can be measured by any method, for example by chromatography, PIV, FBRP, optical methods, piezoelectric sensors, impedance or conductance measurements.

[0059] In a coffee slurry, the ratio of gas in the hydrate fraction to gas in the liquid fraction (H:L) can be between 1:1 and 5:1, preferably between 2:1 and 3:1. For example, a coffee slurry can contain about 1 mol / L of gas trapped in hydrate form and about 0.5 mol / L of dissolved gas. The H:L ratio can be measured by any method, for example, by chromatography, Raman spectroscopy, X-ray scattering, and / or modeling. Preferably, the majority of the gas is trapped in gas hydrates.

[0060] Instant coffee powder manufacturing method The present invention provides a method for producing dry coffee, the method comprising: (a) mixing a coffee slurry containing gas hydrate with a second coffee solution to provide a mixture thereof (i.e., a coffee slurry / coffee solution mix); (b) releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix to provide a foamed coffee solution; (c) drying the foamed coffee solution, preferably by freeze-drying, to provide dried coffee.

[0061] The present invention provides a method for producing instant coffee powder, the method comprising: (a) mixing a coffee slurry containing gas hydrate with a second coffee solution to provide a coffee slurry / coffee solution mix; (b) releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix to provide a foamed coffee solution; (c) drying the foamed coffee solution, preferably by freeze-drying, to provide dried coffee; (d) grinding the dried coffee to provide an instant coffee powder.

[0062] The basic steps for making instant soluble coffee are shown in Figure 1. The method may further include one or more of the steps outlined in Figure 1. A method according to the present invention is shown in Figure 10. The method may further include one or more of the steps outlined in Figure 10.

[0063] Advantageously, mixing the gas into the coffee solution in solid form (e.g., a coffee slurry containing gas hydrate) facilitates mixing of the gas into the coffee solution and / or reduces the time required to gasify the coffee solution and / or reduces the energy required to gasify the coffee solution.

[0064] In the method for producing instant coffee powder according to the present invention, the coffee slurry may be produced by the methods described herein. The coffee slurry may be produced in a side stream (i.e., a clathrate hydrate slurry generator (CLAG)).

[0065] In the method for producing instant coffee powder according to the present invention, the second coffee solution can be produced by any method known to those skilled in the art. The second coffee solution can be present in the main stream. Preferably, the second coffee solution does not contain gas hydrates. The second coffee solution can contain 10% to 70% by weight, 30% to 70% by weight, 50% to 70% by weight, 55% to 65% by weight, 60% to 65% by weight, or approximately 60% by weight of coffee solids. Preferably, the second coffee solution has a higher weight percent of coffee solids than the coffee slurry (i.e., the first coffee solution). For example, the coffee slurry (and first coffee solution) can contain approximately 30% by weight of coffee solids, and the second coffee solution can contain approximately 60% by weight of coffee solids. The second coffee solution may have a viscosity of 10 mPas to 10 Pas, or 10 mPas to 2.5 Pas, or 10 mPas to 1 Pas, or 10 mPas to 100 mPas, or 20 to 100 mPas, or 20 mPas to 60 mPas, or about 20 mPas or more and / or about 100 mPas or less. The viscosity depends on the weight percent of coffee solids, i.e., a higher weight percent will result in a higher viscosity (see Figure 4). For example, a 60 wt. % coffee solution will have a viscosity of 100 mPas at 30 bar, 7°C, and 100 s. -1 At a shear rate of 100 s, a 30 wt. % coffee solution may have a viscosity of approximately 2.3 Pas, while a 30 wt. % coffee solution may have a viscosity of approximately 2.3 Pas at 30 bar, 7°C and 100 s -1 The viscosity may be approximately 10-20 mPas at a shear rate of 100 s. The viscosity is also temperature dependent, with lower temperatures resulting in higher viscosities. The viscosity may be measured by any method known to those skilled in the art, for example, by a rheometer. Preferably, the viscosity is measured at a shear rate of 100 s. -1 The measurements are carried out at a shear rate of 1000 rpm and a temperature of 7°C.

[0066] The coffee slurry (side stream) and the second coffee solution (main stream) can be mixed by adding the coffee slurry to the second coffee solution, i.e., by adding the side stream to the main stream. Mixing the side stream and the main stream produces a coffee slurry / coffee solution mix. Preferably, the coffee slurry / coffee solution mix remains in the main stream until mixing is complete. In some embodiments, the side stream flow rate is 5 to 200 mL / min, or 10 to 100 mL / min, or about 15 mL / min, and the main stream flow rate is 100 to 500 mL / min, or 100 to 200 mL / min, or about 170 mL / min. For example, if the coffee slurry contains CO2 hydrate, the side stream can be added at a rate of 10 to 20 mL / min to the main stream flow at 150 to 200 mL / min. If the coffee slurry contains CO2 / N2 hydrate, the side stream can be added at a rate of 80 to 100 mL / min to the main stream flow at 150 to 200 mL / min. In some embodiments, the ratio of side flow velocity to main flow velocity is less than 1, or between 0.05 and 0.5, or between 0.05 and 0.1, or about 0.08.

[0067] In some embodiments, the coffee slurry is added to the second coffee solution by dispensing (i.e., by adding specific amounts (volumes) of coffee slurry at discrete time intervals). In some embodiments, the amount (volume) of coffee slurry added is between 1 and 1000 cm 3 , 1~100cm 3 , 1~50cm 3 , 10~50cm 3 , or 5 to 20 cm 3 , or about 15 cm 3 In some embodiments, the coffee slurry is added every 1 to 1000 seconds, or every 5 to 200 seconds, or every 60 to 100 seconds. In some embodiments, the coffee slurry is added every 10 to 50 cm 3 is added every 60 to 100 seconds.

[0068] In some embodiments, the amount (volume) and / or rate of coffee slurry addition is sufficient to provide 0.001 to 1 mol / min, or 0.02 to 0.1 mol / min of gas to the second coffee solution. For example, if the coffee slurry includes CO2 hydrate, the volume and rate of slurry addition can be such that 0.02 to 0.1 mol / min of CO2 is provided, and if the coffee slurry includes CO2 / N2 hydrate, the volume and rate of slurry addition can be such that 0.02 to 0.1 mol / min of CO2 and 0.001 to 0.005 mol / min of N2 are provided.

[0069] In some embodiments, the coffee slurry (side stream) and the second coffee solution (main stream) are mixed and / or the side stream is added to the main stream under near-isobaric isothermal (i.e., approximately or about) conditions, preferably isobaric isothermal conditions. "Isobaric isothermal conditions" according to the present invention are conditions under which mixing is carried out at a constant temperature and constant gas pressure. Preferably, the isobaric isothermal conditions are the same as the conditions of the coffee slurry (side stream) before mixing, i.e., the isobaric isothermal conditions refer to the inlet pressure and temperature where the side stream enters the main stream. Nearly isobaric isothermal conditions may be within ±2°C and ±5 bar of the isobaric isothermal conditions. Preferably, the temperature and gas pressure are suitable for the formation and / or retention of gas hydrates, as described above. Thus, the temperature can be -15°C to 15°C, or -10°C to 12°C, or -10°C to 10°C, or -10°C to 8°C, or -8°C to 7°C, or -5°C to 5°C, or about -7°C or higher, -5°C or higher, or -4°C or higher, depending on the gas, coffee solution, and gas pressure, and / or the gas pressure can be 10 to 500 bar, 10 to 300 bar, 10 to 200 bar, 10 to 150 bar, 10 to 100 bar, 10 to 50 bar, 15 to 40 bar, 15 to 35 bar, or 15 to 30 bar, depending on the gas, coffee solution, and temperature. The temperature and pressure required to form and / or maintain gas hydrate are interdependent and vary depending on the gas and solution (e.g., the weight percent solids in the coffee solution). In a preferred embodiment, the coffee slurry and second coffee solution are mixed at a pressure of about 10-38 bar, or about 10 bar or more, and / or at a temperature of -3 to 7.8°C (the coffee slurry contains CO2 hydrate). In another embodiment, the coffee slurry and second coffee solution are mixed at a pressure of about 140-285 bar and / or at a temperature of -2.5 to 5.5°C (the coffee slurry contains N2 hydrate). In a preferred embodiment, the coffee slurry and second coffee solution are mixed at a CO2 / N2 total gas pressure of about 35 bar and / or at a temperature of 1 to 5°C, or about 3°C ​​(the coffee slurry contains a CO2 / N2 mixed hydrate).In some embodiments, the coffee slurry (sidestream) and the second coffee solution (mainstream) are mixed under the same temperature and / or pressure used to produce the coffee slurry containing gas hydrates.

[0070] According to the present invention, the coffee slurry / coffee solution mix is ​​a foamed coffee solution after releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix. Preferably, the dispensing of the coffee slurry and / or mixing of the coffee slurry with the second coffee solution continues until the coffee slurry / coffee solution mix (i.e., the foamed coffee solution) reaches an overrun of 50-500%, or 100-500%, or 100-400%, or 150-400%, or 200-400%, or 250-350%, or about 300%. As used herein, "overrun" refers to the increase in volume of the coffee solution, which can be measured by any method known to those skilled in the art. In some embodiments, after the desired overrun (e.g., 50-500%, or 100-500%, or 150-400%, or 100-400%, or 200-400%, or 250-350%, or about 300%) is reached, the side stream (coffee slurry) is continuously added to the main stream (second coffee solution) at a constant dosing rate, for example, a dosing rate sufficient to provide 0.001-1.5 mol / min, or 0.02-0.1 mol / min, of gas to the second coffee solution, to maintain the desired overrun. In some embodiments, mixing and / or dosing continues until the coffee slurry / coffee solution mix contains 0.01-7.5 mol / L, 0.1-7.5 mol / L, 0.5-2 mol / L, or about 1 mol / L of gas.

[0071] In some embodiments, the method includes the additional step of releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix to provide a foamed coffee solution. Preferably, the method includes the additional step of increasing the temperature and decreasing the pressure, or only decreasing the pressure (i.e., without increasing the temperature). Preferably, this step decomposes any remaining gas hydrates and releases the gas in the coffee slurry / coffee solution mix. The temperature and pressure required to decompose the gas hydrates are interdependent and will vary depending on the gas and solution (e.g., the weight percent solids in the coffee slurry / coffee solution mix). Thus, the gas pressure and temperature will vary depending on the identity of the gas hydrate. The gas pressure may be released (optionally in combination with increasing the temperature). In some embodiments, the gas pressure may be reduced to between 1 bar and 10 bar, or between 5 bar and 10 bar. The temperature may be increased (optionally in combination with reducing the gas pressure). In some embodiments, the temperature of the coffee slurry / coffee solution mix may be increased to above 10°C, above 15°C, or above 20°C. In some embodiments, the temperature of the coffee slurry / coffee solution mix may be increased to between -5°C and 10°C, between -5°C and 5°C, between 0°C and 10°C, between 0°C and 5°C, above about 0°C, or above about 5°C in combination with reducing the gas pressure. Preferably, the gas pressure is released (i.e., the temperature is not increased). For example, for a 30 wt% CO2 (or mixed CO2) hydrate in coffee solution, the gas pressure may be reduced to less than about 10 bar (e.g., 1-10 bar, or 1-5 bar) at a temperature of 1-2°C, or less than 20 bar at a temperature of 5-6°C. For example, for a 30 wt% N2 hydrate in coffee solution, the gas pressure can be reduced to less than about 135 bar (e.g., 1-100 bar, 1-50 bar, 1-20 bar) at a temperature of -2.5°C to 5.5°C.

[0072] In some embodiments, the method for producing instant coffee powder may include the additional step of flash-freezing the foamed coffee solution before drying to provide a stabilized foamed coffee solution. In a preferred embodiment, the stabilized foamed coffee solution is in the form of a solid coffee block. Flash-freezing can stabilize the foam microstructure of the foamed coffee solution by avoiding any further bubble expansion or aggregation. Any flash-freezing method known to those skilled in the art can be used. In some embodiments, the foamed coffee solution is flash-frozen to about -196°C, or about -78°C, or between -196°C and -40°C, or between -80°C and -40°C, or between -80°C and -65°C, preferably to about -60°C. For example, if the flash-freezing method uses liquid nitrogen to stabilize the foamed coffee solution, the solution may be flash-frozen to about -196°C. Alternatively, if the flash-freezing method uses dry ice to stabilize the foamed coffee solution, the solution may be flash-frozen to about -79°C. Preferably, the stabilized foamed coffee solution (e.g. in the form of a solid coffee block) is stored at -80°C to -40°C, or about -60°C. In some embodiments, the step of quick freezing is preceded by an additional step of further releasing the pressure. For example, the method may comprise a step of releasing the pressure (e.g. 15 to 25 bar) to provide a foamed coffee solution, followed by a step of quick freezing (e.g. stabilization with liquid nitrogen), followed by a step of further releasing the pressure (e.g. to 1 bar).

[0073] In some embodiments, the method for producing instant coffee powder may include drying a foamed coffee solution or a stabilized foamed coffee solution (e.g., in the form of a solid coffee block) to produce dried coffee. In a preferred embodiment, the dried coffee is in the form of a dried solid coffee block. The step of drying the (stabilized) foamed coffee solution may use any method known to those skilled in the art, such as spray drying or freeze drying. In a preferred embodiment, the step of drying the (stabilized) foamed coffee solution is freeze-drying. Preferably, freeze-drying reduces and / or avoids rapid sublimation of water in the system, thereby reducing and / or avoiding the aggregation of small gas pockets. Suitable freeze-drying methods for reducing and / or avoiding rapid sublimation of water are well known to those skilled in the art. In some embodiments, the drying rate is 1°C / hour until the (stabilized) foamed coffee solution reaches 0°C, and preferably the initial temperature of the (stabilized) foamed coffee solution is between -60°C and -20°C, preferably about -40°C.

[0074] Grinding the dry coffee (e.g., in the form of a dry solid coffee block) can use any method known to those skilled in the art. Grinding the dry coffee (e.g., in the form of a dry solid coffee block) can further include sieving the ground dry coffee to provide instant coffee powder. After grinding (and optionally sieving), the instant coffee powder can consist of granules having an average diameter of, for example, greater than 0.5 mm and / or less than 4 mm. Preferably, the instant coffee powder granules can have an average diameter of about 3 mm.

[0075] Thus, in some embodiments, a method for producing instant coffee powder comprises: (a) mixing a coffee slurry containing gas hydrate with a second coffee solution to provide a coffee slurry / coffee solution mix; (b) releasing the pressure on the coffee slurry / coffee solution mix to provide a foamed coffee solution; (c) rapidly freezing the foamed coffee solution to provide a stabilized foamed coffee solution; (d) optionally further releasing the pressure; (e) drying the stabilized foamed coffee solution, preferably by freeze-drying, to provide dried coffee; (f) grinding the dried coffee to provide an instant coffee powder.

[0076] instant coffee powder "Instant coffee powder" refers to a dry powder composition that can be reconstituted by the addition of a liquid, such as hot or cold water, milk, or the like. Instant coffee powder can be composed of coffee solids, such as soluble coffee solids. Coffee solids are compounds, other than water, obtained from coffee, such as roasted coffee. Soluble coffee solids are water-soluble compounds typically extracted from coffee beans using water and / or steam. High concentrations of coffee solids can be extracted from roasted coffee by aqueous extraction at temperatures above 100°C, e.g., 130°C to 180°C, where partial hydrolysis of the coffee results in the release of soluble polysaccharides.

[0077] The instant coffee powder of the present invention preferably forms a foam and / or crema on its surface when reconstituted with water, i.e., it can be considered a "foaming instant coffee powder." By "crema" is meant the thick, reddish-brown foam formed on the surface of espresso. Crema may contain solid particles (insoluble coffee sediment), and its continuous phase is an oil-in-water emulsion. For a typical standard espresso coffee cup (1 serving) of 25-30 mL, the crema represents at least 10% of the total volume (Navarini, E. Illy, Food biophysics 2011, volume 6, issue 3, pp: 335-348). In some embodiments, the foam and / or crema impart advantageous sensory properties, such as improved mouthfeel and / or aroma. In some embodiments, the foam and / or crema produced by the instant coffee powder of the present invention has improved texture, stability, and / or greater volume.

[0078] The instant coffee powder of the present invention preferably does not require additional foaming or crema-forming agents to form foam and / or cream on its liquid surface, and therefore the instant coffee powder of the present invention preferably does not contain additional foaming or crema-forming agents (i.e. the instant coffee powder of the present invention may be a pure instant coffee powder).

[0079] The "porosity" of an instant coffee powder is a measure of the void space (pores) and has a value between 0 and 1, or the fraction of the volume of pores over the total volume of the instant coffee powder, as a percentage between 0% and 100%.

[0080] "Closed porosity" is the fraction of the total volume of closed pores in the instant coffee powder. "Open porosity" is the fraction of the total volume of open pores in the instant coffee powder.

[0081] "Foaming porosity" is a measure of the porosity that contributes to foam formation and characterizes the potential foaming ability of the instant coffee powder of the present invention. Closed pores contribute to foaming. Open pores do not contribute to foaming to the same extent as closed pores, or in some cases, do not contribute to foaming at all. Pores with an opening diameter of less than 2 micrometers can contribute to foaming because the capillary pressure in these pores is greater than ambient pressure, which can enable foam formation. Therefore, foaming porosity can be determined by considering closed pores and open pores with an opening diameter of less than 2 micrometers. Foaming porosity is obtained by the ratio of the volume of pores that contribute to foaming to the volume of the aggregate, excluding the volume of open pores with an opening diameter of more than 2 micrometers.

[0082] The size of the pores in the instant coffee powder is given by the "pore size distribution", which may be defined by the incremental volume as a function of pore diameter and / or by the number of pores as a function of pore diameter.

[0083] The size of the closed pores in the instant coffee powder is given by the "closed pore size distribution", which may be defined by the incremental volume as a function of closed pore diameter and / or by the number of closed pores as a function of closed pore diameter.

[0084] Porosity, closed porosity, open porosity, expandable porosity, pore size distribution, expandable pore size distribution, and closed pore size distribution can be measured by any means known in the art. For example, they can be measured by standard measurement methods such as mercury porosimetry, X-ray tomography, SEM, and / or the methods described in the Examples. Pore size can be determined, for example, by examining SEM images, for example, using image analysis software.

[0085] In some embodiments, the instant coffee powder of the present invention has a total porosity (closed and open) of between 60% and 90%, or between 70% and 90%, or between 70% and 85%, or about 78%.

[0086] In some embodiments, the instant coffee powder of the present invention has an expandable porosity of 10%-60%, 15%-50%, 15%-34%, 20%-34%, 25%-34%, 30%-34%, or about 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, or 34%, preferably about 30%, and preferably has closed pores and open pores with an opening diameter of less than 2 micrometers formed from a coffee slurry containing a mixed CO2 / N2 hydrate. In some other embodiments, the instant coffee powder of the present invention has an expandable porosity of 10%-20%, and preferably has closed pores and open pores with an opening diameter of less than 2 micrometers formed from a coffee slurry containing a CO2 hydrate.

[0087] In some embodiments, the instant coffee powder of the present invention has a closed porosity of 10%-60%, 15%-50%, 20%-35%, 20%-34%, 25-34%, 30-34%, or about 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%, preferably about 30%, preferably the closed porosity formed from a coffee slurry containing mixed CO2 / N2 hydrate. In some other embodiments, the instant coffee powder of the present invention has a closed porosity of 10%-20%, preferably the closed porosity formed from a coffee slurry containing CO2 hydrate.

[0088] In some embodiments, the instant coffee powder of the present invention has a bimodal pore distribution. A bimodal pore distribution is a continuous pore size distribution with two distinct modes (i.e., mean sizes). Preferably, the bimodal pore distribution comprises two Gaussian pore distributions, the mode being approximately equal to the mean value of the Gaussian pore distributions.

[0089] In some embodiments, the bimodal pore distribution is a bimodal expandable pore distribution, which is a continuous pore size distribution with two distinct modes: closed pores and open pores (i.e., expanded pores) with an opening diameter of less than 2 micrometers.

[0090] The bimodal pore distribution may comprise (i) pores having a mean diameter (modal diameter) of 20 to 100 micrometers, or 20 to 50 micrometers, or 25 to 45 micrometers, or 30 to 45 micrometers, or 35 to 45 micrometers, or about 40 micrometers; and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers, or less than about 15 micrometers, or less than about 10 micrometers, or less than about 5 micrometers, or 1 to 20 micrometers, or 1 to 18 micrometers, or 1 to 15 micrometers, or 1 to 10 micrometers. and pores having a mean diameter (modal diameter) of about 20 micrometers, or 1 to 5 micrometers, or 2 to 20 micrometers, or 2 to 18 micrometers, or 2 to 15 micrometers, or 2 to 10 micrometers, or 2 to 5 micrometers, or 5 to 20 micrometers, or 5 to 18 micrometers, or 5 to 15 micrometers, or 5 to 10 micrometers, or about 2 micrometers, or about 5 micrometers, or about 10 micrometers, or about 15 micrometers, or about 20 micrometers. In a preferred embodiment, the bimodal pore distribution comprises (i) pores having a mean diameter (modal diameter) of about 20 to 50 micrometers and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 micrometers). In other preferred embodiments, the bimodal pore distribution comprises (i) pores having a mean diameter (modal diameter) of about 25-45 micrometers and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 micrometers), or about 2-20 micrometers, or about 5-15 micrometers. When instant coffee powder is produced using a coffee slurry containing CO2 / N2 hydrate, larger pores may be formed by CO2 and smaller pores may be formed by N2.The larger pores can comprise open pores (including expanded pores) and / or closed pores, preferably the larger pores comprise substantially open pores (i.e., more than 90%, more than 95%, more than 99%, or about 100% of the larger pores are open pores), most preferably the open pores are open pores with an opening diameter of 2 micrometers or more. The smaller pores can comprise closed pores and / or expanded pores (i.e., open pores with an opening diameter of less than 2 micrometers), preferably the smaller pores comprise substantially closed pores (i.e., more than 90%, more than 95%, more than 99%, or about 100% of the smaller pores are closed pores).

[0091] In some embodiments, larger pores contribute 10-99% by volume of the total pore volume, and / or smaller pores contribute 1-90% by volume of the total pore volume. In some other embodiments, larger pores contribute 10-90% by volume of the total pore volume, and / or smaller pores contribute 10-90% by volume of the total pore volume. The volume and / or number of total pores contributed by each mode can be estimated based on the pore size distribution. The pore size distribution can be estimated for each mode, and the contribution ratio calculated based on the total pore size distribution. For example, preferably, the bimodal pore distribution includes two Gaussian pore distributions, and therefore, the area of ​​each Gaussian distribution for each mode can be used to calculate the volume and / or number of total pores contributed by each mode.

[0092] In preferred embodiments, the instant coffee powder of the present invention has a bimodal closed pore distribution. Thus, in some embodiments, the bimodal pore distribution is a bimodal closed pore distribution. A bimodal closed pore distribution is a continuous closed pore size distribution having two distinct modes.

[0093] In some embodiments, the bimodal closed pore distribution comprises (i) closed pores having a mean diameter (modal diameter) of 20 to 100 micrometers, or 20 to 50 micrometers, or 25 to 45 micrometers, or 30 to 45 micrometers, or 35 to 45 micrometers, or about 40 micrometers; and (ii) closed pores having a mean diameter (modal diameter) of less than about 20 micrometers, or less than about 15 micrometers, or less than about 10 micrometers, or less than about 5 micrometers, or 1 to 20 micrometers, or 1 to 18 micrometers, or 1 to 15 micrometers, or 1 to 20 micrometers. and closed pores having a mean diameter (mode diameter) of about 20 to 50 micrometers, or about 20 micrometers, or about 15 micrometers, or about 20 micrometers, or about 10 micrometers, or about 20 micrometers, or about 15 micrometers, or about 20 micrometers, or about 10 micrometers, or about 20 micrometers, or about 15 micrometers, or about 20 micrometers. In a preferred embodiment, the bimodal closed pore distribution comprises (i) closed pores having a mean diameter (mode diameter) of about 20 to 50 micrometers, and (ii) closed pores having a mean diameter (mode diameter) of less than about 20 micrometers (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 micrometers). In other preferred embodiments, the bimodal closed pore distribution comprises (i) closed pores having a mean diameter (modal diameter) of about 25-45 micrometers and (ii) closed pores having a mean diameter (modal diameter) of less than about 20 micrometers (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 micrometers), or about 2-20 micrometers, or about 5-15 micrometers. When instant coffee powder is produced using CO2 / N2 hydrate, larger closed pores may be formed by CO2 and smaller closed pores may be formed by N2.

[0094] In some embodiments, larger pores contribute 10-99% by volume of the total closed pore volume, and / or smaller pores contribute 1-90% by volume of the total closed pore volume. In some other embodiments, larger pores contribute 10-90% by volume of the total closed pore number, and / or smaller pores contribute 10-90% by volume of the total closed pore number. The volume and / or number of total closed pores contributed by each mode can be estimated based on the closed pore size distribution. The closed pore size distribution can be estimated for each mode, and the contribution ratio calculated based on the total closed pore size distribution.

[0095] In some embodiments, the instant coffee powder of the present invention has an expandable porosity of 15% to 34%, or 20% to 34%, or 25% to 34%, or 30% to 34%, or about 30%, and a bimodal pore distribution.

[0096] In some embodiments, the instant coffee powder of the present invention has a foaming porosity of 15% to 34%, or 20% to 34%, or 25% to 34%, or 30% to 34%, or about 30%, and a bimodal pore distribution comprising (i) pores having a mean diameter (modal diameter) of 20 to 100 micrometers and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers, preferably wherein (i) contributes 10 to 99% by volume of the total pore volume and / or (ii) contributes 1 to 90% by volume of the total pore volume. Preferably, the larger pores comprise substantially open pores and the smaller pores comprise substantially closed pores.

[0097] In some embodiments, the instant coffee powder of the present invention has a foaming porosity of 20% and 34% and a bimodal pore distribution comprising (i) pores having a mean diameter (modal diameter) of about 25-45 micrometers and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 micrometers), or about 2-20 micrometers, or about 5-15 micrometers, preferably wherein (i) contributes 10-99% by volume of the total pore volume and / or (ii) contributes 1-90% by volume of the total pore volume. Preferably, the larger pores comprise substantially open pores and the smaller pores comprise substantially closed pores.

[0098] In a preferred embodiment, the instant coffee powder of the present invention has a closed porosity of 20% to 40%, or 20% and 34%, and a bimodal pore distribution.

[0099] In another preferred embodiment, the instant coffee powder of the present invention has a closed porosity of 20% to 40%, or 20% and 34%, and a bimodal pore distribution comprising (i) pores having a mean diameter (modal diameter) of 20 to 100 micrometers and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers, preferably wherein (i) contributes to 10 to 99% by volume of the total pore volume and / or (ii) contributes to 1 to 90% by volume of the total pore volume. Preferably, the larger pores comprise substantially open pores and the smaller pores comprise substantially closed pores.

[0100] In another preferred embodiment, the instant coffee powder of the present invention has a closed porosity of 20% and 34% and a bimodal pore distribution comprising (i) pores having a mean diameter (modal diameter) of about 25-45 micrometers and (ii) pores having a mean diameter (modal diameter) of less than about 20 micrometers (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 micrometers), or about 2-20 micrometers, or about 5-15 micrometers, preferably wherein (i) contributes 10-99% by volume of the total pore volume and / or (ii) contributes 1-90% by volume of the total pore volume. Preferably, the larger pores substantially comprise open pores and the smaller pores substantially comprise closed pores.

[0101] Advantageously, larger (open) pores in instant coffee powder are beneficial in terms of facilitating sample reconstitution and making the instant coffee more permeable to water, while smaller (closed) pores in instant coffee powder are advantageous in terms of foam or crema production.

[0102] In some embodiments, the instant coffee powder further comprises open pores that may be formed by ice crystals and sublimation during freeze drying.

[0103] The instant coffee powder may be for providing a coffee beverage having at least 0.25 mL / g of crema upon reconstitution with water, for example at least 0.75 mL / g of crema upon reconstitution with water.

[0104] The instant coffee powder may comprise granules. Preferably, the instant coffee powder granules have an average diameter of more than 0.5 mm. Preferably, the instant coffee powder granules have an average diameter of less than 4 mm. Most preferably, the instant coffee powder granules have an average diameter of about 3 mm. The average granule diameter can be measured, for example, by a calibrated sieve.

[0105] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including" or "includes" or "containing" or "contains" and are inclusive, i.e., open-ended, and do not exclude additional, unrecited components, elements, or steps. The terms "comprising," "comprises," and "comprised of" also include the term "consisting of."

[0106] As used herein, the term "about" means approximately, in the region of, roughly, or around. When the term "about" is used in conjunction with a numerical value or range, it modifies that numerical value or range by extending the boundaries above and below the stated numerical value(s). In general, the terms "about" and "approximately" are used herein to modify numerical value(s) by 10% above and below the stated value(s).

[0107] [Example] Example 1 - Characterization of gas solubility in coffee solutions, phase diagram of coffee solution-gas systems, and rheology of coffee solutions Gas solubility in coffee solutions Gas solubility in coffee solutions was experimentally evaluated using an intensified high-pressure vessel reactor and pressure sorption decay method, monitoring gas consumption from the headspace with a third-order polynomial gas equation of state. Experiments were performed at 4°C and 10, 20, 30, 35, and 40 bar, and at 10°C and 10, 20, 30, 35, and 40 bar. The initial charge was 100 g of either 30 wt. % or 50 wt. % coffee solution.

[0108] Figure 2 and Table 1 show the experimental results for CO2 solubility in coffee solution. At 35 bar and 4°C, 38.6 mg / g of CO2 was dissolved in a 30 wt% coffee solution. The 30 wt% coffee solution was also tested with N2 at 4°C and 10°C. At 35 bar and 4°C, 0.7 mg / g was dissolved, and at 50 bar and 4°C, 2.94 mg / g was dissolved. At 10°C, no N2 dissolution was detectable in the 30 wt% coffee solution.

[0109] [Table 1]

[0110] Coffee solution-CO2 and coffee solution-N2 phase diagrams The phase diagram for obtaining the coffee solution / CO2 hydrate-liquid-vapor (HLV) stability line was estimated using an isochoric multi-step heating / cooling separation temperature cycle method in a high-pressure stirred tank reactor and high-pressure differential scanning calorimetry (DSC) method.

[0111] Figure 3a shows the equilibrium point obtained for the 30 wt% coffee solution·CO2 system. The obtained point falls between pure water and the hydrate-liquid-vapor boundary region of the 25 wt% sugar solution, suggesting that the well-described 25 wt% sugar solution is a suitable model for the 30 wt% coffee solution.

[0112] Figure 3b contains a phase diagram for mixed hydrates with CO2 / N2 guests in water, adapted from the literature (Kang, SP, et al., 2001. The Journal of Chemical Thermodynamics, 33(5), pp. 513-521). The hydrate-liquid-vapor boundary line is displayed for various CO2 compositions that lie between the boundaries for pure CO2 (two-digit pressure values ​​in bar) and N2 hydrate (three-digit pressure values ​​in bar).

[0113] Rheology of coffee solutions The viscosities of 30 wt%, 40 wt%, 50 wt% and 60 wt% coffee solutions were measured. Figure 4 shows the results of the rheological characterization of the coffee solutions.

[0114] The viscosity dependence on shear rate in Figure 4a was the same at atmospheric pressure and 30 bar. -1 At shear rate scales, the material could be classified as a Newtonian fluid. For the 60 wt% coffee concentrate primarily used in the main line, the viscosity was approximately 2.3 Pas at 30 bar. For the 30 wt% mix primarily used in the high-pressure clathrate hydrate slurry generator (CLAG) reactor, the viscosity was approximately 14–16 mPas. This was consistent with flowmeter measurements in the high-pressure CLAG reactor before CO2 dissolution. During gas dissolution in the high-pressure CLAG reactor, the viscosity increased to a maximum of 30 mPas for the 30 wt% coffee solution at a temperature of approximately 5 °C and a maximum of 60 mPas during hydrate growth. The increase in viscosity indicated gas dissolution and embedding into gas hydrate cages.

[0115] Figure 4b shows the viscosity dependence on temperature, showing a tendency for the viscosity to decrease as the temperature increases.

[0116] Example 2 - Preparation of coffee slurry containing gas hydrate Several combinations of gas type and amount were tested in a high-pressure clathrate hydrate slurry generator (CLAG) reactor to produce coffee slurries containing gas hydrates. Coffee slurries with dissolved gases without gas hydrates were also tested for comparison with the gas hydrate systems. A complete list of experiments is shown in Table 3.

[0117] [Table 2]

[0118] CO2 hydrate coffee slurry A typical protocol for generating CO₂ hydrate slurry from coffee solution in a high-pressure clathrate hydrate slurry generator (CLAG) reactor involved several steps. The high-pressure CLAG reactor was filled with 3 L of 30 wt% coffee solution. Simultaneously, a defined amount of gas (50–400 g) was charged into the gas reservoir cylinder (maximum pressure 35 bar). The SSHE unit was rotated at 800 rpm, and the pump was operated at 40–50 Hz (maximum 330 L h -1 The entire high-pressure CLAG reactor was cooled to a temperature range between 7°C and -8°C, either within or outside the gas hydrate stability zone. The high-pressure CLAG reactor was then pressurized from a gas tank. After supersaturation was achieved, gas hydrate was formed after a certain period of time. The point at which gas hydrate was first observed is called the induction point. The time until the induction point is called the induction time. After the induction point, gas hydrate entered a growth period.

[0119] To reduce the amount of water for certain foaming applications, a high viscosity initial coffee solution was desired. However, higher viscosity slurries (0.3 Pas) were difficult to pump. Therefore, a 30 wt. % coffee solution was selected for pumping tests.

[0120] CO2:N2 hydrate coffee slurry In the experiments, CO2 and N2 were used to form gas hydrates, with CO2 to N2 ratios up to 0.64 tested. CO2 ratios between 0.47 and 0.54 had a uniform flow profile after gas hydrate formation and were easy to handle. After forming a small amount of gas hydrate in the coffee solution using CO2 at approximately 20 bar pressure, N2 was added at a pressure of 35 bar, assuming that the unoccupied hydrogen-bonded cages could be further filled with smaller N2 molecules.

[0121] High-pressure CLAG reactor conditions for feed testing. Figure 5 and Table 4 show the decreasing density and increasing viscosity trends in the high-pressure CLAG reactor tests after gas hydrate appearance for CO2 and CO2:N2 hydrate coffee slurries.

[0122] [Table 3]

[0123] The pressure and temperature in the last row are for the gas hydrate slurry before it was pumped into the EGLI main line. The pressure in the high-pressure CLAG reactor for the CO2 / N2 experiment before nitrogen injection was approximately 19 bar. H stands for hydrate, P stands for pressure, and T stands for temperature.

[0124] The increase in viscosity and decrease in density due to gas dissolution was not significant in tests where no hydrate was present, indicating less gas consumption. To some extent, the density and viscosity could be reported due to the increase in clathrate species in the slurry.

[0125] To estimate gas distribution in coffee slurry tests, the coffee in the system was ignored, and the occupancy, hydration number, and volume fraction of the phases present were calculated using the Colorado School of Mines CSMGEM gas hydrate software (Sloan, ED and CA Koh: Clathrate Hydrates of Natural Gases, p. 752, 2007). A lower range estimate of cage occupancy was obtained for a 30 wt.% coffee solution with CO2, 50% occupancy, and a hydration number of 11.5 (see Teng, H, et al., Chemical Engineering Science, 50(4):559-564, 1995). Observations by Kang et al. (Kang, SP, et al., 2001, The Journal of Chemical Thermodynamics, 33(5), pp. 513-521) and phase diagrams also allowed us to estimate the amount of CO2 / N2 in the hydrate at process conditions. With the low pressure and given CO2 / N2 loading, approximately 2% of the nitrogen was embedded in the hydrate, with the remainder remaining as carbon dioxide. The results are shown in Table 5.

[0126] [Table 4]

[0127] Phase fractions are volumetric, where L represents the liquid, which is water, and H represents the hydrate. The pressure-temperature operating conditions for the given case are given. *In this case, the liquid is considered to be a coffee solution (treated with a thermodynamic model).

[0128] Example 3 - Preparation of instant coffee powder Coffee slurry feeding into the main EGLI line When gas hydrates appeared in the coffee slurry and the system was at equilibrium or completely saturated with gas, the slurry was pumped into the main EGLI line with the settings shown in Table 6. The main line consisted of a modified EGLI (EGLI AG) margarine pilot plant with a separate scraped surface heat exchanger (SSHE) unit. The main line was fed with concentrate containing up to 65 wt.%.

[0129] [Table 5]

[0130] The average feeding rate for feeding was every 5 to 30 seconds for N2 and every 60 to 100 seconds for gas hydrate slurry, with a flow rate of 15.3 cm 3 The valve opening was typically 1 second. Overruns of up to 500% were easily achieved. Typical overruns ranged from 100 to 200% for all foaming media used. The majority of experiments were performed with a 60% by weight coffee solution on the main line.

[0131] A typical gas hydrate slurry pumping is shown in Figure 6a and compared with the situation where coffee was doped with dissolved N2 (Figure 6b).

[0132] In the N2 test, the solution had to be dispensed frequently, and therefore the mixture in the high-pressure CLAG reactor was depleted more quickly during the dispensing process. In the high-pressure CLAG reactor, for solutions containing only dissolved gases and no gas hydrate, it was generally more difficult to regulate the backpressure on the main line when the CLAG reactor pressure fluctuated due to the increased amount of gasified coffee solution that needed to be dispensed. Compared to the gas hydrate-containing slurry, the dissolved gas coffee slurry required a larger dispensing volume (higher dispensing frequency or longer valve opening) from the high-pressure CLAG reactor and a higher scraper speed on the EGLI scraped surface heat exchanger unit. See also Table 6.

[0133] Rapid freezing stabilization The foamed coffee slurries obtained in the previous tests were stabilized to maintain their porosity and gas retention until the freeze-drying step. Rapid freeze stabilization is preferred, which avoids further bubble expansion or agglomeration beyond the expansion valve of the EGLI. For stabilization, the following approach was applied: Trapping the product in solid CO2 pellets at -78.5°C stabilizing the foam microstructure.

[0134] Direct capture of the product in liquid nitrogen at -195.79°C, which simulates a quenching effect.

[0135] The product is trapped in a pre-pressurized and pre-cooled 1 L vessel manufactured by Kisag (Bellach, CH) at 15-20 bar and its contents are rapidly cooled with dry ice or liquid nitrogen. Due to the fact that the pressure / temperature conditions are maintained to some extent in the main pressure / temperature line, some expansion of the product is expected. In this way, gas hydrate can be preserved.

[0136] Capture the product on a 1 cm thick aluminum plate pre-immersed in liquid nitrogen. Slower heat transfer is expected compared to direct liquid nitrogen quenching.

[0137] A two-step process of first annealing at -25°C and a temperature close to the freezing point depression of a 60% by weight coffee solution (-16°C), followed by storage of the samples at -60°C, achieving a very gentle freezing profile that induces ice crystal growth (which can act to freeze-dry the specimens). The annealing was carried out for 1 hour in a freezer box, followed by a slow return to approximately the melting point in a cooling box manufactured by Vebabox (Uden, NL) before storage at -60°C.

[0138] After the samples had stabilized, they were stored in a freezer maintained at -60°C.

[0139] Freeze drying The samples were then freeze-dried. Table 7 shows a typical freeze-drying profile performed in a Millrock Technology freeze drier (Kingston, USA). The freeze-drying was intentionally performed in a long, deliberately designed drying process to avoid rapid sublimation of water in the system and cause aggregation of small gas pockets.

[0140] [Table 6]

[0141] Example 4 - Characterization of quick-frozen and freeze-dried dried coffee samples Crema formation Figure 7 shows an example of reconstituted freeze-dried samples and their crema-forming ability. A 1.6 g sample of instant coffee granules (approximately 3 mm) was reconstituted with 150 mL of water at 85°C.

[0142] The total porosity of the sample was 78%±9%, comparable to the reference instant coffee product which had a porosity of 72.7%.

[0143] Closed porosity is more indicative because it provides information related to crema formation. After freeze-drying of stabilized foamed coffee solutions, small, closed pores containing air were generated. These pores were released when the porous instant coffee powder was reconstituted with hot water. The reference instant coffee product had a closed porosity of 61.2%, with all closed pores ranging from greater than 5 to 20 μm, resulting in a crema layer. A conventional instant coffee product was compared with one with a closed porosity of 6.2%, which did not produce crema. This indicates that the instant coffee powder from this study significantly improved crema formation from instant coffee powder.

[0144] The highest closed porosity achieved for instant coffee products made using CO2 hydrate slurries was 18.9%, see Figure 7a. The best crema emergence (for instant coffee products made using CO2 hydrate slurries) was observed with a closed porosity of 15.7% and a high overrun of 164%.

[0145] Nitrogen was introduced to reduce the pore size. All samples involving N2 had higher closed porosity than CO2 hydrate slurries. With regard to crema, the most successful instant coffee product made using a mixed CO2 / N2 hydrate slurry had a closed porosity of 32%.

[0146] From the given examples, it can be concluded that high overrun, high porosity (e.g., high total porosity, foam porosity and / or closed porosity), and small closed pores (due to nitrogen in mixed gas hydrate, e.g., CO2 / N2>0.54) perform best in crema generation.

[0147] Stomatal distribution Figure 8 shows the best sample for the crema of Figure 7b, formed from CO2 / N2 hydrate, with an overrun of 218%.

[0148] The SEM image shows a bimodal pore distribution, with smaller pores less than 20 μm and larger pores approximately 50 μm. The small, mostly closed pores resemble the reference image formed only from N2 and are due to N2 arising from the hydrate structure. On the other hand, the larger pores due to CO2 are beneficial for facilitating sample reconstitution and making the coffee more susceptible to water penetration. Thus, despite having half the closed porosity of the reference, the sample still produced a cream layer.

[0149] Figure 9 shows samples recovered from the main EGLI line, stabilized, and then analyzed by cryo-SEM. The first sample, with dissolved N2, has a low overrun of 43%, but the pores are very small and closed. Another image, with a CO2 / N2 gas ratio of 0.55, features a very small fraction of closed pores and a higher overrun of 151%.

[0150] The last two examples in Figure 9 show examples with high CO2 loading without N2 at 250x magnification. One sample was a foamed 60 wt% concentrate, the other a 55 wt% concentrate. The 55 wt% coffee concentrate foamed with CO2 produced a foam with slightly larger pores than the 60 wt% coffee concentrate sample. No effect was observed of the type of stabilization of the foamed coffee solution on crema formation.

[0151] These results suggest that ideally, coffee concentrates should be foamed with nitrogen hydrate, but this requires high pressures (up to 300 bar).

[0152] For a sustainable process at lower pressures, CO hydrate or mixed CO / N hydrate are good alternatives for producing instant coffee products that can result in a cream layer. The use of CO hydrate or mixed CO / N hydrate allows for the flexibility and rapid freeze-drying temperature profile desired in industrial applications, and allows for reduced operating pressures compared to pure nitrogen hydrate.

[0153] Furthermore, molecularly embedded nitrogen in mixed CO2 / N2 hydrates appears to create a structure similar to dissolved nitrogen at high pressures (above 150 bar), as seen in the reference samples. The nitrogen fraction in mixed hydrates can be increased by shifting the operating conditions to higher pressures and lower temperatures, increasing the closed porosity of the N2-derived freeze-dried product.

[0154] The advantage of using gas hydrates compared to methods using dissolved gases (i.e., the method used to prepare the reference samples) is that less gas is required to produce an instant coffee product capable of producing a cream layer. Also, the time required to generate hydrates at moderate pressures (35-50 bar) is in the range of minutes, compared to several hours for dissolving nitrogen gas.

[0155] Example 5 - Methods Differential scanning calorimetry (DSC) High-pressure DSC measurements were performed to determine the hydrate-liquid-vapor boundary line for CO2 hydrate formed from coffee solution. The device used was a micro DSC VII (1-7721-3) manufactured by Setaram (Caluire, France). Measurements were performed at atmospheric pressure, 10 bar, 30 bar, and 50 bar for 30 wt% and 50 wt% coffee solutions. The temperatures of the sample and sapphire reference material were recorded in the furnace. The pressure was assumed to be constant throughout the measurements. A sample with a size of less than 100 μg was loaded into a special high-pressure cell and pressurized to a predetermined pressure. The temperature profile in the table below was then applied and repeated for three cycles. The endothermic melting peak for gas hydrate dissociation was identified, and the onset temperature was taken as the CO2 hydrate equilibrium point.

[0156] [Table 7]

[0157] DSC Measurements at Atmospheric Pressure to Determine Freezing Point Depression and Molecular Weight. Differential scanning calorimetry was used to measure the freezing point depression of coffee solutions and their molecular weight. Triplicate samples were measured for 30 wt% and 60 wt% coffee solutions on a DSC822e calorimeter from Mettler Toledo (Ohio, USA). The freezing point depression was estimated as the onset of the endothermic melting event in the STARe software provided by Mettler Toledo. The freezing point depression was then measured at -1.86°C.m. -1The molecular weight was calculated using a freezing point depression constant for the water solvent equal to 186 g / mol (per volume of water solvent). The molecular weight of the coffee powder was found to be 186 g / mol. The respective freezing point depressions were -4.4°C for the 30 wt% coffee solution and -15.5°C for the 60 wt% coffee solution.

[0158] Rheology The viscosities of 30 wt%, 40 wt%, 50 wt%, and 60 wt% coffee solutions were measured using a cylinder-cup-bob-couette geometry at a pressure of 30 bar and at atmospheric pressure in an MRC302 rheometer (Anton Paar, Graz, Austria). Coffee solutions above 60 wt% could not be evaluated well in the rheometer.

[0159] The dependence of viscosity on shear rate and temperature was measured from 1 to 1000 s at a constant temperature of 7°C. -1 The shear rate gradient was performed in the range of 10°C to 0°C (excluding the presence of hydrate). The measurement was then repeated at a pressure of 30 bar. The viscosity change with temperature was measured using a linear temperature gradient from 10°C to 0°C, followed by a 5-minute hold at 0°C and a ramp up to 10°C at the same rate of 2°C / min.

[0160] The measured data was fitted using the following equation:

[0161]

number

[0162] Characteristics of the freeze-dried product The freeze-dried product was ground and sieved to obtain representative granules (3 mm) corresponding to conventional instant coffee. Density, open and closed porosity, and crema formation ability were tested.

[0163] Density Measurement of Freeze-Dried Coffee: The matrix density was measured by a DMA4500M instrument (Anton Paar, Switzerland AG). The sample was introduced into a U-shaped borosilicate glass tube that was excited to vibrate at a frequency dependent on the sample. The density was measured based on specific vibration characteristics. The precision of the instrument was 5.10 for density. -5 g·cm 3 , and the temperature was 0.03°C.

[0164] Porosity Measurement of Freeze-Dried Coffee The apparent density of coffee granules was measured with an Accupyc 1330 pycnometer (Micrometrics Instrument Corporation, USA). This instrument determines density and volume by measuring the volume-corrected helium pressure change within a reading accuracy of 0.03% plus 0.03% of the nominal full-scale cell chamber volume. The open porosity was then calculated from the matrix density and apparent density according to the following equation:

[0165]

number

[0166] The closed porosity was similar to the open porosity measured on a volumetric basis. The freeze-dried specimens were analyzed with a Geopyc 1360 device (Micromeritics, Norcross, USA). The envelope density was measured by a pycnometer based on a displacement method. The samples were placed in a matrix of small, hard particles with a high degree of flowability. A sphere (with a known weight) flowing around the sample would reach the open pores but not the closed pores, thus defining the open porosity.

[0167] Scanning electron microscopy (cryo-SEM) of stabilized frozen porous coffee specimens. The microstructure and pore size were further analyzed by cryo-SEM of stabilized frozen porous coffee specimens. For this purpose, the stabilized samples were stored under liquid nitrogen. The samples were then broken using a scalpel, and representative pieces were then glued to the sample holder using a 60% sugar solution. Preparation was performed under liquid nitrogen. The sample holder was inserted into a vacuum chamber shuttle manipulator arm, which was used to transport the sample to a BAF060 cryo-SEM preparation frozen fraction and etching station (Leica Microsystems, Wetzlar, Germany), pre-cooled to below -150 °C. In the BAF station, the sample was fractured to obtain a freshly prepared surface, and then etched by sublimating the superficial ice layer under vacuum, revealing some areas that may have been hidden due to the long sample preparation. Etching was performed at -110 °C for 1.5 min. The sample was then coated with a 3 nm layer of carbon-metal mix using a controlled electron beam gun at a voltage of 2 kV. The sample was then transferred to the SEM microscope using a Gatan cryo-vacuum-holder shuttle and mounted on the stage. The stigmatism and aperture were set on the microscope and images were taken at various magnifications.

[0168] Scanning electron microscopy of freeze-dried porous coffee specimens (SEM). For scanning electron microscopy of freeze-dried samples for porosity investigation, the samples were glued onto metallic specimen stubs with double-sided conductive tape. If necessary, the samples were then fractured using a razor blade to reveal their internal structure. The samples were coated with a 10 nm gold layer using a Leica SCD500 sputter coater, and images were acquired using a Quanta F200 Scanning Electron Microscope from Thermo Fischer Scientific (Waltham, USA) in high / low vacuum mode.

[0169] All publications mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the disclosed methods, compositions, and uses of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been disclosed in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the disclosed modes for carrying out the invention, which are obvious to those skilled in the art, are intended to be within the scope of the following claims.

Claims

1. 1. Use of a gas hydrate for producing instant coffee powder, wherein the gas comprises air and / or one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably the gas comprises carbon dioxide and / or nitrogen.

2. 1. A method for producing a coffee slurry containing gas hydrate, comprising: (a) providing a first coffee solution; (b) cooling the first coffee solution; (c) pressurizing the first coffee solution with a gas to provide a coffee slurry comprising gas hydrates, the gas being air and / or comprising one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably the gas comprising carbon dioxide and / or nitrogen; A method comprising:

3. 3. The method of claim 2, wherein the first coffee solution is cooled to between -10°C and 10°C, or between -8°C and 7°C, or between -5°C and 5°C, or to about -5°C or above, and / or the gas pressure is between 10 and 300 bar, or between 10 and 150 bar, or between 10 and 100 bar, or between 10 and 50 bar, or between 15 and 40 bar, or between 15 and 35 bar, or between 15 and 30 bar.

4. 4. The method according to claim 2 or 3, wherein the method comprises the steps of cooling the first coffee solution to 0-5°C, or about 3°C, and pressurizing the first coffee solution with carbon dioxide, preferably to 15-25 bar, or about 20 bar, before pressurizing the first coffee solution with nitrogen, preferably to 30-300 bar, 30-150 bar, 30-100 bar, 30-50 bar, 30-40 bar, or about 35 bar.

5. The method according to any one of claims 2 to 4, wherein the method further comprises dispersing the gas hydrate in the coffee slurry.

6. 1. A coffee slurry comprising a gas hydrate, wherein the gas is air and / or comprises one or more of carbon dioxide, nitrogen, nitrous oxide and argon, preferably wherein the gas comprises carbon dioxide and / or nitrogen.

7. 6. The method according to any one of claims 2 to 5, wherein the coffee slurry comprises carbon dioxide, preferably at 0.5 to 5 mol / L, 1 to 5 mol / L, 1 to 2 mol / L, about 1 mol / L or about 1.6 mol / L, and / or nitrogen, preferably at 0.01 to 0.5 mol / L, 0.02 to 0.1 mol / L or about 0.05 mol / L.

8. A coffee slurry as described in claim 6, wherein the coffee slurry contains carbon dioxide, preferably 0.5 to 5 mol / L, 1 to 5 mol / L, 1 to 2 mol / L, about 1 mol / L, or about 1.6 mol / L, and / or nitrogen, preferably 0.01 to 0.5 mol / L, 0.02 to 0.1 mol / L, or about 0.05 mol / L.

9. 8. The method according to any one of claims 2 to 5 and 7, wherein the coffee slurry has a ratio of gas in the hydrate fraction to gas in the liquid fraction (H:L) of from 1:1 to 5:1, preferably from 2:1 to 3:

1.

10. A coffee slurry as described in claim 6 or 8, wherein the coffee slurry has a ratio of gas in the hydrate fraction to gas in the liquid fraction (H:L) of 1:1 to 5:1, preferably 2:1 to 3:

1.

11. 10. The method of any one of claims 2 to 5, 7 and 9, wherein the coffee slurry comprises between 10% and 50%, between 20% and 40%, or about 30% by weight of coffee solids.

12. A coffee slurry as described in any one of claims 6, 8, and 10, wherein the coffee slurry contains 10% to 50% by weight, 20% to 40% by weight, or about 30% by weight of coffee solids.

13. 12. The method of any one of claims 2 to 5, 7, 9 and 11, wherein the coffee slurry has a viscosity of 10 to 100 mPas, or 20 to 100 mPas, or 30 to 65 mPas, or about 30 mPas or more and / or about 100 mPas or less, preferably the viscosity of the coffee slurry is greater than that of the first coffee solution.

14. A coffee slurry described in any one of claims 6, 8, 10 and 12, wherein the coffee slurry has a viscosity of 10 to 100 mPas, or 20 to 100 mPas, or 30 to 65 mPas, or about 30 mPas or more, and / or about 100 mPas or less.

15. 1. A method for producing instant coffee powder, comprising: (a) mixing a coffee slurry containing gas hydrate with a second coffee solution to provide a coffee slurry / coffee solution mix; (b) releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix to provide a foamed coffee solution; (c) drying the foamed coffee solution, preferably by freeze-drying, to provide dried coffee; (d) grinding the dried coffee to provide an instant coffee powder; A method comprising:

16. The method according to claim 15, wherein the coffee slurry is produced by the method according to any one of claims 2 to 5, 7, 9, 11, and 13, or is a coffee slurry containing the gas hydrate according to any one of claims 6, 8, 10, 12, and 14.

17. 17. The method according to claim 15 or 16, wherein the coffee slurry comprises carbon dioxide, preferably at 0.5 to 5 mol / L, 1 to 5 mol / L, 1 to 2 mol / L, about 1 mol / L or about 1.6 mol / L, and / or nitrogen, preferably at 0.01 to 0.5 mol / L, 0.02 to 0.1 mol / L or about 0.05 mol / L.

18. 18. The method of any one of claims 15 to 17, wherein the second coffee solution comprises between 10% and 70%, between 30% and 70%, between 50% and 70%, between 55% and 65%, between 60% and 65%, or about 60% by weight of coffee solids.

19. 19. The method according to any one of claims 15 to 18, wherein the coffee slurry is added to the second coffee solution under substantially isobaric and isothermal conditions, preferably the substantially isobaric and isothermal conditions being a temperature of -10°C to 10°C, or -8°C to 7°C, or -5°C to 5°C, or about -5°C or above, and / or a gas pressure of 10 to 300 bar, or 10 to 150 bar, or 10 to 100 bar, or 10 to 50 bar, or 15 to 40 bar, or 15 to 35 bar, or 15 to 30 bar.

20. A method according to any one of claims 15 to 18, wherein the foamed coffee solution reaches an overrun of 50 to 500%, or 200 to 400%, or 250 to 350%, or about 300%.

21. 21. The method of any one of claims 15 to 20, wherein in the step of releasing the pressure and / or increasing the temperature of the coffee slurry / coffee solution mix, the pressure is released to between 1 bar and 10 bar, or between 5 bar and 10 bar, and / or the temperature of the coffee slurry / coffee solution mix is ​​increased to between -5°C and 10°C, or to above 0°C, or to about 5°C, or above 10°C.

22. A method according to any one of claims 15 to 21, wherein the method comprises the additional step of flash-freezing the foamed coffee solution before drying it.

Images