Nitrogen infused soluble cold bubble soluble coffee and method of making

Abstract

The present invention relates to nitrogen infused soluble cold froth soluble coffee and a method of preparation, in particular to a liquid coffee beverage comprising liquid coffee infused with nitrogen gas to produce a fresh cold frothy and creamed beverage.

Description

[0001] This application is a divisional application of the international application filed on June 8, 2017, with application number PCT / EP2017 / 064025 and the invention title "Soluble Cold Brew Instant Coffee Injected with Nitrogen and Preparation Method Thereof". The international application entered the Chinese national phase on November 21, 2018, with application number 201780031416.1. Technical Field

[0002] This invention relates to nitrogen-infused soluble cold-brew instant coffee and its preparation method. In particular, this invention relates to dried coffee powder with improved flavor and stability properties. Background Technology

[0003] Today, nitrogen is widely used for storing and dispensing carbonated beverages such as beer and soda. Nitrogen-infused coffee (e.g., "nitrogen coffee") has recently become a popular drink. Nitrogen coffee is typically cold-brewed coffee with dissolved nitrogen. Cold-brewed coffee is considered low-yield coffee, with a yield ranging from 10% to 15% and coffee solids ranging from 0.5% to 1.5%. This cold drink is ultra-low in calories, contains no added sugar or alcohol, and is a completely natural product. A key aspect of this type of chilled beverage is the foam. Nitrogen bubbles in cold coffee exhibit a spectacular cascading effect, first appearing through nucleation of dissolved gas and sinking to the bottom of the receiver (mug or glass), then rising to the surface while ultimately forming a rich, creamy foam layer. It is known that coffee flavorings in espresso or ready-to-drink (RTD) coffee are not ultra-stable, making the delivery of high-quality flavorings in cold brew challenging. Furthermore, for nitrogen-infused coffee available today, cold brew preparation is necessary before the actual nitrogen-infused coffee can be made. This involves additional effort at breweries, coffee shops, and / or bars to first prepare the liquid cold brew stock, which is typically an overnight process. Cold brewing in the form of instant powder, which can be prepared on demand, would be advantageous. Instant coffee is soluble coffee powder that dissolves in water, providing consumers with a quick and convenient way to prepare coffee.

[0004] Coffee is typically prepared by brewing roasted and ground coffee beans with hot water. The flavor characteristics of coffee are influenced by many factors, including roasting conditions, grind size, and the amount of time the coffee grounds are in contact with hot water during brewing.

[0005] Instant coffee can be prepared by drying such brewed materials to form a powder; a typical drying method is freeze drying.

[0006] While instant coffee is popular with consumers for its convenience, it is known that this type of soluble coffee powder often has different flavor characteristics than freshly brewed coffee. Consumers who prefer freshly brewed coffee often perceive instant coffee as not fresh enough.

[0007] With consumers showing an increasing preference for freshly brewed or even cold-brewed coffee, there is considerable commercial interest in developing instant coffee with improved flavor characteristics: instant coffee that more closely replicates the experience of drinking high-quality freshly brewed coffee, but can be advantageously sold as a stable, dry coffee powder in existing coffee canisters. This improved instant coffee will be able to target consumers who prefer the taste of ultra-high-quality freshly brewed or cold-brewed coffee, but appreciate the convenience of instant coffee.

[0008] Due to the chemical properties of freshly brewed high-quality coffee, it is extremely difficult to dry and to produce a sufficiently stable powder. Freeze-dried powder prepared from high-quality coffee brewing can be highly hygroscopic (it attracts and absorbs water), tending to form a "cake-like" shape or collapse in the container.

[0009] Several methods have been used to try to solve this problem.

[0010] Besides the nitrogen-infused coffee mentioned above, trace amounts of nitrogen are also used in packaged beverages to replace oxygen during packaging. WO2014176102 describes a sterile, hot-brewed packaged coffee or espresso beverage that contains trace amounts of nitrogen in the packaging to replace oxygen and increase the beverage's shelf life. EP0745329 describes a carbonated coffee beverage sealed under pressure in a pressure-resistant, closed container, the beverage being based on coffee extract, and wherein the coffee beverage is sealed in the closed container in the presence of CO2 and nitrogen.

[0011] In the conventional preparation of soluble coffee, extraction is completed in two steps. The first extract is prepared at or near boiling water temperature and has a brewed flavor profile. The second extract, obtained from the pre-extracted grind, is prepared at a higher temperature of approximately 160°C to 204°C and has a strong bitterness and a "processed" flavor profile.

[0012] However, while the first extract possesses the desired properties, its limitations in high molecular weight compounds make it difficult to produce stable freeze-dried coffee powder when used alone. Therefore, to produce instant coffee powder with good stability, the two extracts are combined, sacrificing some positive sensory qualities.

[0013] An alternative to using only the first extract to produce stable instant coffee powder is to add a leavening agent, such as maltodextrin. However, when using this method, the resulting coffee powder is no longer "100% coffee," and it cannot be labeled as such.

[0014] Therefore, there is a need in the art for improved soluble instant coffee powder and its preparation method that are not affected by the above-mentioned disadvantages. Summary of the Invention

[0015] The present invention addresses the aforementioned problems (freshness and stability) of the prior art by providing soluble instant coffee and a method for preparing the same, as detailed in the claims.

[0016] In one aspect, the present invention provides a liquid coffee beverage comprising liquid coffee and nitrogen, the liquid coffee having a dehydrated carbohydrate content between 10% w / w and 20% w / w, wherein the liquid coffee is derived from soluble coffee powder. The advantage of using soluble coffee powder is that the liquid coffee can be prepared immediately and nitrogen can be injected into the mixture. This method avoids the cumbersome process of preparing cold-brewed coffee with a long brewing cycle of 8 to 24 hours to prepare the liquid coffee.

[0017] In one embodiment, soluble coffee powder is obtained by a method comprising the following steps: (i) extracting coffee solids from roasted and ground coffee beans using water at a temperature between 0°C and 110°C to obtain a first coffee extract; (ii) filtering the first coffee extract using a selective permeation membrane to reduce the concentration of low molecular weight components and provide a filtered coffee extract; and (iii) drying the filtered coffee extract to form a dried coffee powder.

[0018] In another embodiment, the soluble coffee powder may be obtained from a dried roasted and ground coffee product comprising roasted and ground coffee granules impregnated and / or coated with at least 10% by weight of soluble coffee solids, wherein the soluble coffee solids are extracted at a temperature below 60°C. In one embodiment, the dried roasted and ground coffee product is blended with roasted and ground coffee beans that are not impregnated and / or coated with soluble coffee solids, or blended with used ground coffee and / or micronized roasted coffee.

[0019] In one embodiment of the invention, the nitrogen gas is pure nitrogen gas having at least 99.5% N2.

[0020] In one aspect of the invention, the dried, roasted, and ground coffee product as defined above includes the following steps: a) Extracting roasted and ground coffee beans at a temperature below 60°C; b) Cool the coffee extract from step a) to a temperature between 4°C and 10°C; c) The cooled coffee extract from step b) is mixed with roasted and ground coffee not extracted in step a), wherein the ratio of soluble coffee solids to roasted and ground coffee is between 1:1 and 1:10, thereby impregnating and / or coating the roasted and ground coffee particles with the soluble coffee solids; and d) Drying the roasted and ground coffee that has been impregnated and / or coated in step c).

[0021] In another aspect of the invention, the dried, roasted, and ground coffee product as defined above includes the following steps: a) Roasted and ground coffee is mixed with water at a temperature below 60°C, wherein the ratio of roasted and ground coffee to water is between 1:1 and 1:5, to obtain a slurry; b) Extracting a slurry of roasted and ground coffee in a vacuum chamber by applying a pressure between 75 mbar and 400 mbar at a temperature between 10°C and 35°C for a duration between 1 and 12 minutes; and c) Drying the slurry from step b).

[0022] Furthermore, it was a pleasant surprise to discover that injecting nitrogen into such filtered coffee extract preparations provided a better foam volume that remained stable over time.

[0023] In one embodiment, the water temperature is between 0°C and 100°C (e.g., between 20°C and 50°C, between 10°C and 40°C, between 20°C and 40°C, or between 20°C and 30°C).

[0024] In one embodiment, the water temperature is approximately 0°C, 10°C, approximately 15°C, approximately 20°C, approximately 25°C, approximately 30°C, approximately 35°C, approximately 40°C, approximately 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or 110°C.

[0025] In one embodiment, the coffee extract is passed through a membrane with a molecular weight cutoff of 0.1 kDa to 100 kDa. The membrane can be an organic or inorganic material.

[0026] In one embodiment, the dried coffee powder contains a proportion of coffee compounds, wherein the ratio of the concentration of high molecular weight compounds to the concentration of low molecular weight compounds (as defined by size exclusion chromatography) is at least 5.

[0027] In one implementation, the filtered coffee extract is concentrated, for example, by reverse osmosis or low-temperature vacuum evaporation, before drying.

[0028] In one implementation, the filtered coffee extract is dried using freeze drying, vacuum belt drying, or spray drying.

[0029] In one embodiment, the coffee flavoring agent is applied before filtration and then blended with the filtered coffee extract before drying. Attached Figure Description

[0030] Figure 1 A flowchart illustrating an example method according to the present invention is presented.

[0031] Figure 2 The SEC chromatogram of coffee extract prepared using water at 25°C is presented.

[0032] Figure 3 The foam volume and time measurements of coffee extract infused with nitrogen using the present invention are presented. Detailed Implementation

[0033] According to the present invention, the term "beverage" refers to any non-carbonated aqueous liquid substance that is a homogeneous liquid and substantially free of flavorful solids due to the dissolved components.

[0034] According to the present invention, dispensing a chilled beverage refers to opening the system's stopcock / flow deflector to allow chilled, "nitrogen-infused" beverage to flow from the system into a receiver, such as a glass, mug, or other drinking container. Throughout the following description, the term "nitrogen-infused" will be used to describe nitrogen-rich coffee beverages infused with N2 or N2O or N2 / CO2 or N2 / N2O / CO2. If the embodiment specifically involves an N2 / CO2 mixture or specifically involves N2 infusion only, the actual gas composition is explicitly disclosed.

[0035] The dispensing of refrigerated beverages infused with nitrogen is an element of this invention, wherein reducing the pressure of the gas-injected beverage causes the dissolved gas to nucleate, preparing microbubbles, thereby obtaining unique properties that distinguish the dispensed beverage by enhancing its flavor and / or appearance. For example, the appearance and stability of the foam over time, and the taste and aroma of coffee delivered through the beverage.

[0036] The term "dehydrated carbohydrates" refers to a carbohydrate distribution that is essentially mannose, arabinose, and galactose. The total content ranges from 10% w / w to 20% w / w. In one embodiment, the carbohydrate distribution of the coffee of the present invention may be, for example, about 15.7 w / w, comprising essentially 6.1% mannose, 6% galactose, and 2.6% arabinose. In another embodiment, the carbohydrate distribution of the coffee of the present invention may be, for example, about 10.7 w / w, comprising essentially 3.3% mannose, 4% galactose, and 3% arabinose. The content of dehydrated carbohydrates is determined by high-performance chromatography using an anion-exchange stationary phase and amperometric detection, and after complete sample hydrolysis. Size exclusion chromatography is used to perform the carbohydrate molecular weight distribution. Then, online hydrolysis and colorimetric detection are performed using sulfuric acid with the addition of 3,5-dihydroxytoluene. Therefore, the response is proportional to the total carbohydrate monomers because 3,5-dihydroxytoluene is selective for carbohydrates.

[0037] The present invention provides a dry coffee powder that can be obtained by means of: membrane filtration of a low-temperature extract of roasted and ground coffee beans to reduce the concentration of low molecular weight components, and drying the filtered coffee extract.

[0038] The inventors have discovered that dried coffee powder suitable for use as instant coffee and possessing highly desirable brewed coffee flavor characteristics can be prepared by using membrane filtration to reduce the concentration of low molecular weight (LMW) components in brewed coffee extract prior to the drying process. The prepared dried coffee powder exhibits good stability properties and low hygroscopicity, enabling it to be stored for extended periods and making it suitable for use as instant coffee. Furthermore, it has been surprisingly found that infusing nitrogen gas into the extract prepared from the dried coffee powder provides a better foam volume that remains stable over time.

[0039] Membrane filtration reduces the concentration of LMW components while simultaneously increasing the ratio of high molecular weight (HMW) components to LMW components in the filtered coffee extract.

[0040] By using membrane filtration to reduce the concentration of low molecular weight components in brewed coffee extract, a stable instant coffee powder is obtained.

[0041] Extraction is the process of extracting coffee solids (such as soluble coffee solids) from roasted and ground coffee beans (usually using water) to form a solution known as coffee extract.

[0042] The method of the present invention uses a low-temperature extract of roasted and ground coffee beans. As used herein, the term "low-temperature extract" preferably refers to a coffee extract obtained using water at a temperature between 0°C and 110°C.

[0043] The method of this invention uses membrane filtration to reduce the concentration of low molecular weight components in coffee extract. Therefore, the coffee extract is passed through a membrane that selectively permeates the LMW (low molecular weight) components of the coffee extract, thereby separating these components and reducing their concentration in the coffee extract. By reducing the concentration of the LMW components, the ratio of HMW (high molecular weight) components to LMW components increases accordingly.

[0044] In a preferred embodiment, the term "low molecular weight component" refers to compounds present in the coffee extract (coffee solids) with a molecular weight less than about 1 kDa (e.g., less than about 0.9 kDa, 0.8 kDa, 0.7 kDa, 0.6 kDa, or 0.5 kDa), and the term "high molecular weight component" refers to compounds present in the coffee extract (coffee solids) with a molecular weight greater than about 1 kDa (e.g., greater than about 1.1 kDa, 1.2 kDa, 1.3 kDa, 1.4 kDa, or 1.5 kDa).

[0045] The inventors have discovered that when the ratio of HMW component to LMW component (as defined by size exclusion chromatography) is at least 5 (e.g., at least 5, at least 5.5, at least 6, at least 6.5 or at least 7), a dry coffee powder with particularly advantageous properties, such as advantageous stability properties, is prepared.

[0046] The present invention provides a method for preparing dried coffee powder, the method comprising membrane filtration of a low-temperature extract of roasted and ground coffee beans to reduce the concentration of low molecular weight components, and drying the filtered coffee extract.

[0047] In a preferred embodiment, the method includes the following steps: (i) extracting coffee solids from roasted and ground coffee beans using water, preferably at a temperature between 0°C and 110°C, to obtain a first coffee extract; (ii) filtering the first coffee extract using a selective permeation membrane to reduce the concentration of low molecular weight components, wherein the low molecular weight coffee solids passing through the membrane form a permeate. The high molecular weight coffee solids retained by the membrane form a retainer; and (iii) drying the retainer to form a dry coffee powder.

[0048] The method of the present invention includes low-temperature extraction using water, preferably at a temperature between 0°C and 110°C, to obtain a first coffee extract.

[0049] In one embodiment, the water temperature is between 0°C and 110°C (e.g., between 20°C and 50°C, between 10°C and 40°C, between 20°C and 40°C, or between 20°C and 30°C). In another embodiment, the water temperature is about 10°C, about 15°C, about 20°C, about 25°C, about 30°C, about 35°C, about 40°C, about 45°C, or about 50°C.

[0050] Roasted coffee beans are ground before extraction. Any suitable coffee beans can be used. The methods for roasting and grinding coffee beans to obtain the desired properties are well known in the art.

[0051] Extraction can be carried out in any suitable extraction vessel, such as a fixed-bed reactor or a continuous countercurrent extractor.

[0052] The extraction yield of a coffee extract refers to the percentage of coffee solids transferred (i.e., extracted) to water during the extraction step. The extraction yield can be controlled using the extraction water temperature and the water-to-coffee bean ratio. The inventors have discovered that coffee extracts prepared at low yields provide particularly advantageous flavor characteristics when used in the method of the present invention.

[0053] Following extraction, a "first coffee extract" is obtained. The first coffee extract is filtered using a membrane capable of reducing the concentration of the LMW component (e.g., a component with a molecular weight less than about 1 kDa). The membrane is selectively permeable, with a molecular weight cutoff value that allows only the LMW component to pass through it. In one embodiment, the membrane has a molecular weight cutoff of 1 kDa, meaning that compounds with a molecular weight greater than about 1 kDa are retained by the membrane.

[0054] Therefore, coffee solids with a molecular weight smaller than the membrane's molecular weight cutoff (i.e., the LMW fraction of the coffee extract) can pass through the filtration membrane, while coffee solids with a molecular weight larger than the membrane's molecular weight cutoff (i.e., the HMW fraction of the coffee extract) cannot pass through the filtration membrane and are thus retained in the coffee extract. Thus, using this type of selective permeation membrane filtration separates the coffee extract into two distinct fractions: the LMW fraction that flows through the filtration membrane is called the permeate, while the HMW fraction retained by the filtration membrane is called the retention fraction.

[0055] The permeate can be optionally recycled for use in separate coffee products.

[0056] In one embodiment, the filtered coffee extract contains a ratio of at least 5 HMW component to LMW component.

[0057] As described above, the inventors have discovered that when the concentration ratio of HMW components (e.g., those with a molecular weight greater than about 1 kDa) to LMW components (e.g., those with a molecular weight less than about 1 kDa) is at least 5 (e.g., at least 5, at least 5.5, at least 6, at least 6.5, or at least 7), dry coffee powder with particularly advantageous properties (such as stability properties) can be prepared.

[0058] To improve the efficiency of the filtration process, the filtrate can be recycled and subjected to the filtration process multiple times.

[0059] The filtration step can be performed using cross-flow filtration, where the fluid flow is tangential to the membrane surface, or using "dead-end" filtration, where the fluid flow is perpendicular to the membrane, or using any other membrane fractionation technique.

[0060] Membranes suitable for use in the method of the present invention include nanofiltration membranes with a molecular weight cutoff of 0.1 kDa to 100 kDa.

[0061] The specifications of a suitable example membrane are as follows: Table 1: Examples of Membrane Properties

[0062] The appropriate membrane size will vary depending on the scale of the fabrication process.

[0063] The percolation step can be performed in conjunction with the filtration step. The percolation step consists of adding dilution water to the retained product and then removing a percolation fraction in an amount equal to the amount of dilution water added.

[0064] After the filtration step, the residue (i.e., the filtered coffee extract) is dried to form soluble coffee powder.

[0065] Suitable methods for drying coffee extract to prepare soluble coffee powder (instant coffee) are known in the art and include freeze-drying and spray-drying. Therefore, in one embodiment, filtered coffee extract is freeze-dried to form dried coffee powder. In another embodiment, filtered coffee extract is spray-dried to form dried coffee powder.

[0066] In the freeze-drying process, the liquid coffee extract is frozen at a temperature of approximately -20°C to approximately -40°C before being heated under low pressure. Applying low pressure can remove the water components from the frozen mixture (such as through sublimation) without requiring high temperatures, which may degrade the flavor and other properties of the coffee extract.

[0067] Spray drying is an alternative to freeze drying. In spray drying, liquid coffee extract is sprayed through small nozzles into heated drying gas. This produces dried coffee particles that can then be collected.

[0068] The method of the present invention may include an additional concentration step prior to the drying step. Such a concentration step can be used to increase the intensity of the coffee extract and improve its flavor characteristics. Thus, in one embodiment, the filtered coffee extract (retaine) is concentrated prior to drying, optionally using reverse osmosis or low-temperature vacuum evaporation, freeze concentration, or any other technique known in the art.

[0069] The aroma of coffee comes from a variety of different chemical compounds that make up the flavor components. Coffee flavoring agents are an important quality that can influence consumers' perception of the taste and aroma of coffee. If a coffee product lacks the aroma that is usually associated with it, consumers' perception of coffee may be adversely affected. This can be a problem in the instant coffee industry, where the extraction, concentration, and drying processes may reduce or remove coffee flavoring agents. For these reasons, it may be advantageous to compensate for the coffee flavoring agents released during coffee processing and to reintroduce these flavoring agents into the coffee extract before drying.

[0070] Therefore, in one embodiment, a coffee flavoring agent is extracted from roasted and ground coffee beans before the extraction of coffee solids, and the coffee flavoring agent is then blended with the filtered coffee extract before drying.

[0071] Methods for extracting coffee flavorings prior to drying and subsequently reintroducing them into coffee extracts are known in the art. An example of a suitable method is vacuum extraction (VAX). Methods for replenishing coffee flavorings are described in WO 1999 / 052378 and WO 2001 / 013735.

[0072] The dried coffee powder of the present invention has good stability properties, making it suitable for use as instant coffee. Instant coffee is typically packaged in cans and sold in cans, and it can be stored at room temperature for a long time. Therefore, in one embodiment, the dried coffee powder of the present invention is advantageously stable at room temperature for at least six months.

[0073] Those skilled in the art will understand that they are free to combine all the features of the invention described herein without departing from the scope of the invention disclosed herein.

[0074] Example

[0075] Preferred features and embodiments of the invention will now be described by way of non-limiting examples.

[0076] Example 1

[0077] Preparation of dried coffee powder.

[0078] The flowchart of the embodiment is shown in Figure 1middle.

[0079] The coffee beans are roasted and ground. A vacuum extraction method is used to extract the coffee flavoring agent from the roasted and ground coffee beans; the flavoring agent is stored for later reintroduction into the process.

[0080] The roasted grounds with flavoring extracted were introduced into the extractor, and coffee solids were extracted using water at 25°C and a water-to-coffee ratio of 4.0.

[0081] The coffee extract obtained above was then subjected to a nanofiltration process using a semi-permeable membrane with a molecular weight cutoff of 1 kDa. Low molecular weight components were filtered into the permeate, while high molecular weight components remained in the retention medium.

[0082] The filtered coffee extract in retainer form contains HMW and LMW components in a ratio of approximately 5 (HMW to LMW, as defined by SEC techniques).

[0083] The filtered coffee extract was freeze-dried to prepare a stable, dry coffee powder.

[0084] Example 2

[0085] Preparation using different membranes

[0086] In a series of preliminary laboratory-scale screening experiments, various polymer ultrafiltration (UF) and nanofiltration (NF) membranes with molecular weight cutoffs (MWCO) ranging from 500 Da to 20,000 Da were used to fractionate cold-brew coffee extracts. The membranes were equipped with 84 cm⁻¹ membranes. 2 Fractionation is performed on a plate-and-frame unit with a membrane area, and it operates at temperatures between 10°C and 60°C and pressures up to 30 bar.

[0087] Initial screening tests determined that the NF membrane (molecular weight cutoff of 1 kDa) was particularly suitable for the fractionation of low-temperature coffee extracts. The membrane was selected based on its performance in terms of permeate flux, cleanability, and its ability to adequately fractionate and separate low molecular weight coffee compounds from the permeate, ensuring that the resulting retention can be used to produce a dryable product with excellent sensory qualities.

[0088] Example 3

[0089] Preparation of prototype dried coffee powder.

[0090] Extraction experiments were conducted using a pilot plant-scale extraction method. To evaluate the effect of temperature on the extract, three experiments were performed to prepare coffee extract at temperatures of 25°C, 50°C, and 85°C.

[0091] A two-module nanofiltration system (membrane area 11m²) was used, both for pilot-scale operation. 2 The system is used to fractionate the obtained extract in batch mode at ambient temperature. A concentration factor (CF) of 4.0 is achieved during the initial fractionation. The retentate is then subjected to percolation to wash away further low molecular weight compounds. The percolation step consists of adding dilution water to the retentate product and then removing a percolate fraction equal in volume to the added dilution water.

[0092] The results of membrane performance in terms of permeate flux and solids compensation are summarized in Table 2.

[0093] Table 2: Membrane performance for preparing coffee extract fractions

[0094] Fragrance agents are added to the percolated residue to produce a flavored freeze-dried powder.

[0095] Example 4

[0096] Size exclusion chromatography (SEC) analysis.

[0097] Size exclusion chromatography was used to analyze the filtered coffee extract prepared using the method of the present invention.

[0098] Coffee extract was separated using HPLC (High Performance Liquid Chromatography) with two tandem size exclusion columns (Superose 60 and Superdex Peptide, from GE Healthcare). Water was used as the mobile phase at a flow rate of 0.5 mL / min. Peaks were visualized using a refractive index detector. The chromatographic run time was 120 minutes.

[0099] The compounds that form coffee extract can be visualized. SEC chromatography showed two distinct peak groups ( Figure 3 The eluted substances before 60 minutes contain high molecular weight compounds, while the eluted peaks after 60 minutes contain low molecular weight compounds.

[0100] Determine the peak areas for the two peak groups. Calculate the ratio of the peak area of ​​the high molecular weight (HMW) substance to the peak area of ​​the low molecular weight (LMW) substance.

[0101] The coffee extract prepared using the method (25°C) of this invention was analyzed using this technique. SEC chromatography is shown. Figure 3 The high molecular weight peaks and low molecular weight peaks were visualized, and the ratio of high molecular weight compounds to low molecular weight compounds was calculated to be 5.0.

[0102] The retention prepared using membrane filtration was further freeze-dried into a dry coffee powder. Compared to powder prepared from the extract without membrane filtration, the filtered extract forms a relatively stable powder.

[0103] Example 5

[0104] Reference sample

[0105] As described in WO2009 / 040249, a coffee beverage is prepared by reconstructing soluble coffee powder infused with nitrogen. This powder is used as a reference.

[0106] A stable powder, consisting of 1.3% by weight of soluble coffee granules filled with N2, was dispersed in water at 4°C to obtain a liquid composition. The solubility is poor, and some clumps are visible in the beverage and foam. The foam level is extremely low, and the bubbles are excessively dispersed.

[0107] Example 6

[0108] Preparation of cold coffee beverages infused with nitrogen .

[0109] Using the stable powder described in Example 1, a 30-liter coffee solution was prepared by metering in cold water with 1.3% coffee solids. This solution was placed in a small container pressurized to 3-4 bar using nitrogen. The container was placed in a cold room at 4-8°C for 48 hours. The pressure was checked periodically to ensure a minimum of 3 bar. After 48 hours, the container was connected to a standard beer tap and a nitrogen cylinder to release the liquid through the tap. The beverage was served into glass mugs. Good foamy and frothy beverages with a cascade of foam were recorded.

[0110] Beverage characterization

[0111] The beverage is dispensed via a stopcock in the form of uniform foam, which is made of tiny bubbles that are evenly dispersed throughout the beverage.

[0112] After the beverage is prepared, the bubbles instantly froth due to the density difference between the air and the continuous liquid phase.

[0113] After 3 minutes, most of the bubbles have frothed and formed a foam layer on top of the beverage: coffee crema.

[0114] Coffee crema evolves over time due to bubble coalescence, Oswald ripening, and liquid expulsion.

[0115] Photometric measurements were used to characterize the beverages. Photographs of the samples were taken from top and / or side views using CoffeeCam (Newtone Technonogies, France) under controlled light conditions, followed by robust and accurate image analysis in the CIE Lab color space.

[0116] In the specific case of layer detection (i.e., coffee crema on top of the liquid coffee phase), layers can be viewed as discontinuities in color within the beverage.

[0117] The foam was also characterized in terms of its texture using a standard rheometer (Discovery HR2, TA Instruments, US) with cup and blade geometry. Flow profiles were performed for a range of 0.1 s⁻¹ to 100 s⁻¹.

[0118] High shear viscosity and yield stress are used to define the rheological properties of foam.

[0119] Figure 3 The results of the foaming properties and foam stability measurements of the beverage of the present invention are shown.

Claims

1. A method for preparing a dried coffee powder suitable for use as instant coffee and having highly desirable brewed coffee flavor characteristics, said dried coffee powder having good stability properties and low hygroscopicity, said method comprising the following steps: (i) Using water at a temperature between 30°C and 50°C, coffee solids are extracted from roasted and ground coffee beans to obtain a first coffee extract; (ii) The first coffee extract is filtered using a selective permeation membrane with a molecular weight cutoff of 1 kDa to reduce the concentration of low molecular weight components, wherein the low molecular weight coffee solids passing through the selective permeation membrane form a permeate, and the high molecular weight coffee solids retained by the selective permeation membrane form a retainer. and (iii) Dry the residue to form dry coffee powder; The concentration ratio of components with a molecular weight greater than 1 kDa to components with a molecular weight less than 1 kDa in the dried coffee powder is at least 5.

2. The method of claim 1, wherein the retained product is concentrated prior to drying.

3. Dry coffee powder that can be obtained by the method of claim 1 or 2.

4. Use of the dried coffee powder of claim 3 for the production of a nitrogen-infused coffee beverage.

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