An espresso coffee liquid and a method for preparing the same

Abstract

The application discloses an ultra-concentrated coffee liquid and a preparation method thereof. The preparation method comprises the following steps: S1, roasting and grinding coffee beans to obtain coffee powder; S2, mixing the coffee powder and a composite enzyme with water, extracting, filtering, and collecting a gas phase generated in the extraction process to obtain a first aroma; S3, screening the extracted liquid through an ultrafiltration membrane, and modifying and aging the extracted liquid at 4-6 DEG C to obtain an aged liquid; S4, performing three-stage gradient vacuum concentration on the aged liquid to obtain a coffee concentrate; collecting a gas phase generated in the vacuum concentration process to obtain a second aroma; and S5, mixing the first aroma and the second aroma, condensing, concentrating, and then adding the concentrated aroma into the coffee concentrate and uniformly mixing to obtain the ultra-concentrated coffee liquid. The application has the effect of improving the stability of coffee with a solid content of more than 70 DEG Brix.

Description

Technical Field

[0001] This application relates to the field of coffee processing technology, and in particular to an ultra-concentrated coffee liquid and its preparation method. Background Technology

[0002] Coffee concentrate is a liquid coffee product made by grinding, extracting, and concentrating roasted coffee beans. It combines the convenience of instant coffee with the flavor and quality of freshly ground coffee. Consumers can quickly obtain a cup of authentic coffee beverage simply by diluting it with water or milk. With the continued penetration of global coffee consumption culture and the rapid development of ready-to-drink coffee and new tea beverage formats, the market demand for coffee concentrate has experienced explosive growth. In end-use applications of coffee concentrate, high-concentration products are increasingly favored by the market due to their advantages such as high flexibility in preparation, low storage and transportation costs, and long shelf life. Ultra-concentrated coffee concentrate can be used as a coffee masterbatch for freeze-dried coffee production, as a base for solid coffee ingredient preparation, and as a concentrate for blending high-end ready-to-drink coffees.

[0003] Currently, the industrial preparation of coffee concentrate typically involves the following main steps: roasting and grinding coffee beans, mixing them with water at a specific material-to-liquid ratio, extracting the concentrate, removing coffee grounds through coarse filtration, dehydrating and concentrating the concentrate through vacuum evaporation or thin-film concentration, and then sterilizing and bottling to obtain the finished product. The soluble solids content of coffee concentrate generally has an upper limit of 50-58°Brix. Once the solids concentration exceeds 60°Brix, irreversible defects such as polysaccharide crystallization, coffee gum gelation, polyphenol polymerization and precipitation, flavor carbonization, and a sudden increase in viscosity that prevents bottling occur. Summary of the Invention

[0004] To improve the stability of coffee with high solids content, this application provides an ultra-concentrated coffee liquid and a method for preparing the same.

[0005] In a first aspect, this application provides a method for preparing ultra-concentrated coffee liquid, employing the following technical solution: A method for preparing ultra-strong coffee liquid includes the following steps: S1. Roast and grind the coffee beans to obtain coffee powder; S2. The coffee powder and the complex enzyme are mixed with water and extracted. The liquid phase obtained after extraction is filtered to obtain the extract. The complex enzyme includes cellulase and mannanase. The gas phase generated during the extraction process is collected to obtain the first aroma. S3. The extract is sieved through an ultrafiltration membrane and modified and aged at 4-6°C to obtain an aged solution. S4. The aging liquid is first vacuum concentrated to 38-42°Brix at 0.078-0.082 MPa, then vacuum concentrated to 58-62°Brix at 0.086-0.090 MPa, and finally vacuum concentrated to 70-78°Brix at 0.093-0.095 MPa to obtain coffee concentrate; the gas phase generated during the vacuum concentration process is collected to obtain the second aroma. S5. Mix the first aroma and the second aroma, condense and concentrate, then add to the coffee concentrate and mix evenly to obtain an ultra-concentrated coffee liquid.

[0006] By adopting the above technical solution, this application firstly utilizes the synergistic hydrolysis of compound enzymes (cellulase and mannanase) to selectively degrade cellulose and mannan in the coffee cell wall. This improves the solids extraction rate and pre-breaks the long chains of mannan molecules, thereby reducing the inherent risks of gelation and crystallization at high concentrations. Secondly, ultrafiltration membrane sieving further precisely retains large-molecule tannins and impurities while preserving flavor molecules and functional polyphenols. Combined with low-temperature modification and ripening at 4-6℃, this promotes adaptive remodeling of the coffee polysaccharide branch structure. Furthermore, the elimination of crystallization nuclei, along with the complementary effects of these two processes, provides multiple safeguards for the liquid stability of the high-solids system. Secondly, the three-stage gradient vacuum concentration, maintained at a low temperature of ≤35℃ throughout the process, progressively increases the solids content to 70-78°Brix, effectively preventing heat-induced flavor degradation and browning reactions caused by high-temperature concentration. Simultaneously, a low-temperature condensation system efficiently enriches dissipated volatile aroma components, and the recovered aroma condensate is refilled into the concentrate, achieving efficient recovery and precise replenishment of aroma components, ensuring the integrity and authenticity of the coffee flavor at ultra-high concentrations. The synergistic effect of these steps allows the product to consistently achieve an ultra-high solids content of over 70°Brix without the addition of any flavorings, preservatives, sweeteners, or thickeners, with no polysaccharide crystallization, no gelation, and no polyphenol precipitation, while also exhibiting excellent flowability, filling performance, and long-term storage stability.

[0007] Optionally, in step S1, the baking temperature is 205-210℃.

[0008] By adopting the above technical solution, this application controls the roasting temperature at 205-210℃, which is in the medium-dark roasting range. Within this temperature range, the Maillard reaction and caramelization reaction of coffee beans are fully carried out, which can form rich and layered flavor substances. At the same time, it avoids the carbonized bitterness caused by excessive temperature and the insufficient flavor development caused by excessively low temperature, thus providing the best flavor precursor material basis for subsequent extraction.

[0009] Optionally, in step S2, the extraction includes pre-extraction at 20-30℃ for 20-30 min, followed by main extraction at 50-60℃ for 40-60 min.

[0010] By adopting the above technical solution, this application employs a two-stage extraction process. First, pre-extraction is carried out at a low temperature of 20-30℃, allowing water to slowly penetrate into the interior of coffee powder particles, while simultaneously dissolving temperature-sensitive flavor substances such as small-molecule volatiles of floral, fruity, acidic, and aromatic compounds. Then, the temperature is raised to 50-60℃ for main extraction, which accelerates the enzymatic reaction of cellulose and mannan within the optimal temperature range of the complex enzymes, fully releasing the soluble solids encapsulated within the cell walls. At the same time, this temperature avoids the oxidative decomposition of polyphenols such as chlorogenic acid by high temperatures, thus maximizing the preservation of the functional components and flavor integrity of the coffee.

[0011] Optionally, in step S2, the weight ratio of coffee powder to water is 1:(4-6).

[0012] By adopting the above technical solution, this application controls the weight ratio of coffee powder to water at 1:(4-6). This material-to-liquid ratio ensures extraction efficiency while reducing energy consumption and time costs in the subsequent concentration stage. The appropriate material-to-liquid ratio allows coffee powder particles to be fully dispersed in water, and the enzymatic reaction to proceed evenly. This avoids insufficient extraction caused by an excessively low material-to-liquid ratio, as well as increased concentration load and flavor dilution caused by an excessively high material-to-liquid ratio.

[0013] Optionally, in step S2, the mass of the complex enzyme is 0.15-0.2% of the mass of the coffee powder, and the mass ratio of the cellulase to the mannanase is (3-5):1.

[0014] By adopting the above technical solution, this application controls the amount of compound enzyme added to 0.15-0.2% of the coffee powder mass, and sets the mass ratio of cellulase to mannanase to (3-5):1. This ratio precisely matches the polysaccharide composition characteristics of the coffee cell wall. Cellulase, as the dominant enzyme, preferentially disrupts the cellulose backbone structure of the cell wall, exposing the encapsulated mannan substrate; mannanase specifically degrades high-molecular-weight galactomannan into low-molecular-weight oligosaccharide fragments, fundamentally eliminating its ability to form a gel network in high-concentration systems. The synergistic effect of the two enzymes at this specific ratio ensures both sufficient cell wall breakdown to improve solids yield and precise control of polysaccharide molecular weight distribution.

[0015] Optionally, in step S3, the molecular weight cutoff of the ultrafiltration membrane is 10,000-30,000 Da.

[0016] By adopting the above technical solution, this application selects an ultrafiltration membrane with a molecular weight cutoff of 10,000-30,000 Da to perform molecular sieving of the extract. This cutoff range can accurately retain high molecular weight tannins, condensed polyphenol polymers and residual macromolecular colloids with molecular weights greater than the cutoff value. These macromolecular substances are prone to polymerization precipitation or gelation under high concentration conditions, which are the main factors leading to the instability of the concentrate. At the same time, key flavor substances in coffee (such as chlorogenic acid, caffeine, melanoidins and other functional components) and low molecular weight mannan oligosaccharides produced by enzymatic hydrolysis can pass through the membrane pores smoothly, ensuring the integrity of flavor and the high retention rate of functional active ingredients.

[0017] Optionally, in step S4, the temperature of the entire vacuum concentration process is ≤35℃.

[0018] By adopting the above technical solution, this application controls the temperature throughout the entire vacuum concentration process below 35°C, effectively avoiding the accelerated thermal degradation and browning reaction of coffee flavor substances caused by high temperatures. Under this low-temperature condition, heat-sensitive flavor precursors and functional components such as chlorogenic acid and trigonelline are effectively protected, preventing excessive Maillard reactions and inhibiting the formation of high-molecular-weight brown pigments, thereby ensuring the stability of the color and the purity of the flavor of the ultra-concentrated coffee liquid.

[0019] Optionally, in step S5, the condensation temperature is -2 to 0°C.

[0020] By adopting the above technical solution, this application controls the reflux temperature at -2 to 0°C. By using extremely low temperature conditions, the volatile aroma components (such as 2-furfuryl mercaptan, pyrazines, furanones and other key aroma compounds) that escape with water vapor during vacuum concentration are efficiently condensed and captured. This avoids the failure of these low-boiling-point aroma substances to be effectively condensed and recovered due to excessively high temperatures, thereby maximizing the aroma recovery rate.

[0021] Optionally, in step S5, mixing is carried out by high-pressure homogenization, wherein the pressure of the high-pressure homogenization is 30-40 MPa and the temperature of the high-pressure homogenization is 10-15℃.

[0022] By adopting the above technical solution, this application uses high-pressure homogenization at 30-40MPa to mix the condensate and concentrate. The strong shear force and cavitation effect generated by high-pressure homogenization enable the aroma components to achieve uniform dispersion and stable embedding at the molecular level in the ultra-high concentration matrix. At the same time, the homogenization temperature is controlled at 10-15℃, which effectively prevents aroma volatilization loss and flavor denaturation caused by local temperature rise during the homogenization process, and ensures the high efficiency and uniformity of aroma backfilling.

[0023] Secondly, this application provides a method for preparing ultra-strong coffee liquid to obtain ultra-strong coffee liquid.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. This application first utilizes the synergistic hydrolysis of a complex enzyme (cellulase and mannanase) to selectively degrade cellulose and mannan in the coffee cell wall. This improves the solids extraction rate and pre-breaks the long chains of mannan molecules, reducing the inherent risks of gelation and crystallization at high concentrations. Secondly, ultrafiltration membrane sieving further precisely retains large-molecule tannins and impurities while preserving flavor molecules and functional polyphenols. Combined with low-temperature modification and ripening at 4-6℃, this promotes adaptive remodeling of the coffee polysaccharide branch structure and eliminates crystallization. The core and the two complement each other, providing multiple guarantees for the liquid stability of the high-solids system. Secondly, the three-stage gradient vacuum concentration, maintained at a low temperature of ≤35℃ throughout, progressively increases the solids content to 70-78°Brix, effectively avoiding heat-induced flavor degradation and browning reactions caused by high-temperature concentration. Simultaneously, the low-temperature condensation system efficiently enriches the dissipated volatile aroma components, and the recovered aroma condensate is refilled into the concentrate, achieving efficient recovery and precise replenishment of aroma components, ensuring the integrity and authenticity of the coffee flavor at ultra-high concentrations. The synergistic effect of these steps allows the product to stably achieve an ultra-high solids content of over 70°Brix without adding any flavorings, preservatives, sweeteners, or thickeners, with no polysaccharide crystallization, no gelation, and no polyphenol precipitation, while also possessing excellent flowability, filling performance, and long-term storage stability. 2. This application employs a two-stage extraction process. First, pre-extraction is carried out at a low temperature of 20-30℃, allowing water to slowly penetrate into the interior of the coffee powder particles, while simultaneously dissolving temperature-sensitive flavor compounds such as small-molecule volatiles of floral, fruity, acidic, and aromatic compounds. Then, the temperature is raised to 50-60℃ for main extraction, which accelerates the enzymatic reaction of cellulose and mannan within the optimal temperature range of the complex enzymes, fully releasing the soluble solids encapsulated within the cell walls. At the same time, this temperature avoids the oxidative decomposition of polyphenols such as chlorogenic acid by high temperatures, thus maximizing the preservation of the functional components and flavor integrity of the coffee. 3. This application uses high-pressure homogenization at 30-40MPa to mix the condensate and concentrate. The strong shear force and cavitation effect generated by high-pressure homogenization enable the aroma components to achieve uniform dispersion and stable encapsulation at the molecular level in the ultra-high concentration matrix. At the same time, the homogenization temperature is controlled at 10-15℃, which effectively prevents aroma volatilization loss and flavor degradation caused by local temperature rise during the homogenization process, and ensures the high efficiency and uniformity of aroma backfilling. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] This application discloses a method for preparing ultra-concentrated coffee liquid, including the following steps: S1. Roast coffee beans at 205-210℃ and grind them into coffee powder with a particle size of 30-40 mesh. S2. Mix the coffee powder, compound enzymes (cellulase and mannanase) with water at a weight ratio of 1:(4-6). Pre-extract at 20-30℃ for 20-30 minutes, then perform main extraction at 50-60℃ for 40-60 minutes. Collect the liquid phase obtained after extraction, filter it to remove coffee grounds, and obtain the extract. Collect the gas phase generated during the extraction process to obtain the first aroma. S3. The extract is sieved through an ultrafiltration membrane with a molecular weight cutoff of 10,000-30,000 Da, and modified and aged at 4-6℃ for 40-60 min to obtain an aged solution. S4. The aging liquid is first vacuum concentrated to 38-42°Brix at a vacuum degree of 0.078-0.080 MPa, then vacuum concentrated to 58-62°Brix at a vacuum degree of 0.086-0.090 MPa, and finally vacuum concentrated to 70-78°Brix at a vacuum degree of 0.093-0.095 MPa. The temperature is controlled to be ≤35°C throughout the vacuum concentration process to obtain coffee concentrate. The gas phase generated during the vacuum concentration process is collected to obtain the second aroma. S5. Introduce the first and second aromas into the aroma recovery system, condense at -2℃ to 0℃ for 20-30 minutes, flash evaporate at 135-145℃ and 0.30-0.32MPa for 10-20 minutes, condense at -2℃ to 0℃ for 20-30 minutes, and then add them to the coffee concentrate. Mix well to obtain an ultra-concentrated coffee liquid.

[0027] All raw materials used in the embodiments of this application are commercially available, wherein: Coffee beans, Beijing Jinmilan Coffee Co., Ltd.; Cellulase, Shanghai Jianye Industrial Co., Ltd.; Mannanase, Shanghai Jianye Industrial Co., Ltd.

[0028] Example 1 A method for preparing ultra-strong coffee liquid includes the following steps: S1. Roast coffee beans at 205℃ for 12 minutes, cool to room temperature, and grind to a particle size of 30 mesh to obtain coffee powder; S2. Mix 1 part by weight of coffee powder with 4 parts by weight of water, add 0.0012 parts by weight of cellulase and 0.0003 parts by weight of mannanase, pre-extract at 20°C for 30 minutes, then heat to 50°C for main extraction for 60 minutes (nitrogen micro-positive pressure with oxygen content ≤1.2% throughout the process), collect the liquid phase obtained after extraction, filter to remove coffee grounds, and obtain the extract; collect the gas phase generated during the extraction process to obtain the first aroma. S3. The extract is sieved through an ultrafiltration membrane with a molecular weight cutoff of 20000 Da, the permeate is collected, and the mixture is modified and matured at 4°C for 60 min to obtain the matured solution. S4. First, vacuum concentrate the aging liquid at a vacuum degree of 0.078 MPa until the solid content in the solution is 40°Brix. Then, adjust the vacuum degree to 0.086 MPa and vacuum concentrate it until the solid content in the solution is 60°Brix. Finally, adjust the vacuum degree to 0.093 MPa and vacuum concentrate it until the solid content in the solution is 70°Brix. Control the temperature of the entire vacuum concentration process to ≤35℃ to obtain coffee concentrate. Collect the gas phase generated during the vacuum concentration process to obtain the second aroma. S5. Introduce the first and second aromas into the aroma recovery system, condense at -2℃ for 20 min, flash evaporate at 135℃ and 0.30 MPa for 20 min, condense at -2℃ for 20 min, and obtain an aroma concentrate. Add the aroma concentrate to the coffee concentrate, with the mass of the aroma concentrate being 1.8% of the mass of the coffee concentrate, and stir at 400 rpm for 40 min to obtain an ultra-concentrated coffee.

[0029] Example 2 A method for preparing ultra-strong coffee liquid includes the following steps: S1. Roast coffee beans at 208℃ for 10 minutes, cool to room temperature, and grind to a particle size of 35 mesh to obtain coffee powder; S2. Mix 1 part by weight of coffee powder with 5 parts by weight of water, add 0.0015 parts by weight of cellulase and 0.0003 parts by weight of mannanase, pre-extract at 25°C for 25 minutes, then heat to 55°C for main extraction for 50 minutes, collect the liquid phase obtained after extraction, filter to remove coffee grounds, and obtain the extract; collect the gas phase generated during the extraction process to obtain the first aroma. S3. The extract is sieved through an ultrafiltration membrane with a molecular weight cutoff of 10000 Da, the permeate is collected, and the mixture is modified and matured at 5°C for 50 min to obtain the matured solution. S4. First, vacuum concentrate the aging liquid at a vacuum degree of 0.080 MPa until the solid content in the solution is 40°Brix. Then, adjust the vacuum degree to 0.088 MPa and vacuum concentrate it until the solid content in the solution is 60°Brix. Finally, adjust the vacuum degree to 0.094 MPa and vacuum concentrate it until the solid content in the solution is 75°Brix. Control the temperature of the entire vacuum concentration process to ≤35℃ to obtain coffee concentrate. Collect the gas phase generated during the vacuum concentration process to obtain the second aroma. S5. Introduce the first and second aromas into the aroma recovery system, condense at 0℃ for 30 min, flash evaporate at 140℃ and 0.31 MPa for 15 min, condense at 0℃ for 30 min, and obtain an aroma concentrate. Add the aroma concentrate to the coffee concentrate, with the mass of the aroma concentrate being 2.0% of the mass of the coffee concentrate, and stir at 500 rpm for 30 min to obtain an ultra-concentrated coffee.

[0030] Example 3 A method for preparing ultra-strong coffee liquid includes the following steps: S1. Roast coffee beans at 210℃ for 8 minutes, cool to room temperature, and grind to a particle size of 40 mesh to obtain coffee powder; S2. Mix 1 part by weight of coffee powder with 6 parts by weight of water, add 0.0015 parts by weight of cellulase and 0.0005 parts by weight of mannanase, pre-extract at 30°C for 20 minutes, then heat to 60°C for main extraction for 40 minutes. Collect the liquid phase obtained after extraction, filter to remove coffee grounds, and obtain the extract; collect the gas phase generated during the extraction process to obtain the first aroma. S3. The extract is sieved through an ultrafiltration membrane with a molecular weight cutoff of 30,000 Da, the permeate is collected, and the mixture is modified and matured at 6°C for 40 min to obtain the matured solution. S4. First, vacuum concentrate the aging liquid at a vacuum degree of 0.082 MPa until the solid content in the solution is 42°Brix. Then, adjust the vacuum degree to 0.090 MPa and vacuum concentrate it until the solid content in the solution is 62°Brix. Finally, adjust the vacuum degree to 0.095 MPa and vacuum concentrate it until the solid content in the solution is 78°Brix. Control the temperature of the entire vacuum concentration process to ≤35℃ to obtain coffee concentrate. Collect the gas phase generated during the vacuum concentration process to obtain the second aroma. S5. Introduce the first and second aromas into the aroma recovery system, condense at -2℃ for 20 min, flash evaporate at 145℃ and 0.32 MPa for 10 min, condense at -2℃ for 20 min to obtain aroma concentrate. Add the aroma concentrate to the coffee concentrate, the mass of the aroma concentrate being 2.5% of the mass of the coffee concentrate, and stir at 600 rpm for 20 min to obtain ultra-concentrated coffee.

[0031] Comparative Example 1 The difference between this comparative example and Example 2 is that in this comparative example, no modification and ripening are performed in step S3. After ultrafiltration membrane sieving, the mixture directly enters step S4 for concentration. The remaining steps are the same as in Example 2. The specific steps are as follows: S1, roast coffee beans at 208℃ for 10 minutes, cool to room temperature, and grind to a particle size of 35 mesh to obtain coffee powder; S2, mix 1 part by weight of coffee powder with 5 parts by weight of water, add 0.0015 parts by weight of cellulase and 0.0003 parts by weight of mannanase, pre-extract at 25℃ for 25 minutes, then heat to 55℃ for main extraction for 50 minutes, filter to remove coffee grounds, and obtain the extract; collect the gas phase generated during the extraction process to obtain the first aroma; S3, sieve the extract through an ultrafiltration membrane with a molecular weight cutoff of 10000 Da to obtain the permeate; S4, first sieve the permeate under a vacuum of 0.080M Vacuum concentration was carried out at 0.088 MPa until the solid content in the solution reached 40°Brix. The vacuum was then adjusted to 0.094 MPa and concentrated to 60°Brix. The temperature was maintained at ≤35℃ throughout the entire vacuum concentration process to obtain coffee concentrate. The gas phase generated during the vacuum concentration process was collected to obtain the second aroma. In step S5, the first and second aromas were introduced into an aroma recovery system, condensed at 0℃ for 30 min, flash-evaporated at 140℃ and 0.31 MPa for 15 min, and condensed at 0℃ for 30 min to obtain an aroma concentrate. The aroma concentrate was added to the coffee concentrate at a mass of 2.0% of the coffee concentrate mass and stirred at 500 rpm for 30 min to obtain an ultra-concentrated coffee.

[0032] Comparative Example 2 The difference between this comparative example and Example 2 is that in step S4 of this comparative example, a one-step concentration is used instead of a three-stage gradient vacuum concentration. The other steps are the same as in Example 2. Specifically, in step S4, the aging liquid is directly vacuum concentrated to 75°Brix at a vacuum degree of 0.094MPa and a temperature of ≤35° to obtain coffee concentrate; the gas phase generated during the vacuum concentration process is collected to obtain the second aroma.

[0033] Performance Test 1 The solids content and stability of the ultra-concentrated coffee liquids prepared in Examples 1-3 and Comparative Examples 1-2 were determined. Solids content was detected according to the method for detecting soluble solids in GB / T 12143-2008 "General Analytical Methods for Beverages". The ultra-concentrated coffee liquids were subjected to a 30-day accelerated test at 40℃ and 75%RH, and the turbidity of the ultra-concentrated coffee liquids before and after the test was measured. Turbidity was measured according to the method in HJ1075-2019 "Determination of Turbidity in Water - Turbidity Meter Method". The coffee liquid was diluted to 0.2°Brix, and its turbidity data were measured. The turbidity change rate was calculated, and the results are shown in Table 1. Turbidity change rate = (Turbidity after test - Turbidity before test) / Turbidity before test × 100%.

[0034] Table 1. Performance of the ultra-concentrated coffee liquids in Examples 1-3 and Comparative Examples 1-2

[0035] As shown in Examples 1-3 and Table 1, the solid content of the ultra-concentrated coffee liquid prepared in this application is above 70.2°Brix, and the turbidity change rate is below 28.8%. This indicates that the present application can stably achieve an ultra-high solid content of above 70°Brix and has excellent long-term storage stability through the synergistic effect of steps such as compound enzyme synergistic hydrolysis, ultrafiltration membrane sieving and low-temperature modification and ripening, three-stage gradient vacuum concentration and aroma recovery and backfilling.

[0036] As shown in Example 2, Comparative Example 1, and Table 1, the turbidity change rate of the ultra-concentrated coffee liquid prepared in Example 2 of this application is 23.7%, which is significantly better than that of Comparative Example 1. This indicates that the low-temperature modification and ripening step of this application can promote the remodeling of the branched structure of coffee polysaccharides and eliminate crystallization nuclei, which plays an important role in ensuring the liquid stability of the high solids system.

[0037] As shown in Example 2, Comparative Example 2, and Table 1, the turbidity change rate of the ultra-concentrated coffee liquid prepared in Example 2 of this application was 23.7%, which was significantly better than that of Comparative Example 2. This indicates that the three-stage gradient vacuum concentration of this application, by progressively increasing the vacuum degree and solid content, can effectively avoid polysaccharide crystallization and gelation caused by one-time high concentration, which is beneficial to improving the long-term storage stability of the product.

[0038] Example 4 Based on Example 2, the difference lies in the following: In step S5, mixing is performed by high-pressure homogenization, while the other steps remain the same as in Example 2. Specifically, in step S5, the first and second aromas are introduced into the aroma recovery system, condensed at 0°C for 30 min, flash-evaporated at 140°C and 0.31 MPa for 15 min, and condensed at 0°C for 30 min to obtain an aroma concentrate. The aroma concentrate is added to the coffee concentrate, with the mass of the aroma concentrate being 2.0% of the mass of the coffee concentrate, and homogenized at 30 MPa and 15°C for 15 min to obtain an ultra-concentrated coffee.

[0039] Example 5 Based on Example 2, the difference lies in the following: In step S5, mixing is performed by high-pressure homogenization, while the other steps remain the same as in Example 2. Specifically, in step S5, the first and second aromas are introduced into the aroma recovery system, condensed at 0°C for 30 min, flash-evaporated at 140°C and 0.31 MPa for 15 min, and condensed at 0°C for 30 min to obtain an aroma concentrate. The aroma concentrate is added to the coffee concentrate, with the mass of the aroma concentrate being 2.0% of the mass of the coffee concentrate, and homogenized at 40 MPa and 10°C for 5 min to obtain an ultra-concentrated coffee.

[0040] Performance Test 2 The stability of the ultra-concentrated coffee liquids prepared in Examples 4-5 was determined. The test method was the same as that in Performance Test 1, and the test results are shown in Table 2 below.

[0041] Table 2 Performance of the ultra-concentrated coffee liquid in Examples 2 and 4-5

[0042] As shown in Examples 2, 4-5, and Table 2, the turbidity change rate of the ultra-concentrated coffee liquid prepared in Examples 4-5 of this application is below 18.6%, which is significantly better than that in Example 2. This indicates that the strong shear force and cavitation effect generated by high-pressure homogenization in this application can enable the backfilled aroma components to achieve uniform dispersion and stable encapsulation at the molecular level in the ultra-high concentration matrix, further improving the long-term storage stability of the ultra-concentrated coffee liquid.

[0043] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing ultra-concentrated coffee liquid, characterized in that, Includes the following steps: S1. Roast and grind the coffee beans to obtain coffee powder; S2. The coffee powder and the complex enzyme are mixed with water and extracted. After extraction, the liquid phase is filtered to obtain the extract. The complex enzyme includes cellulase and mannanase. The gas phase produced during the extraction process is collected to obtain the first aroma; S3. The extract is sieved through an ultrafiltration membrane and modified and aged at 4-6°C to obtain an aged solution. S4. The aging liquid is first concentrated under vacuum at 0.078-0.082 MPa to 38-42° Brix, then concentrated under vacuum at 0.086-0.090 MPa to 58-62° Brix, and finally concentrated under vacuum at 0.093-0.095 MPa to 70-78° Brix to obtain coffee concentrate; The gas phase produced during the vacuum concentration process is collected to obtain the second aroma; S5. Mix the first aroma and the second aroma, condense and concentrate, then add to the coffee concentrate and mix evenly to obtain an ultra-concentrated coffee liquid.

2. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S1, the baking temperature is 205-210℃.

3. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S2, the extraction includes pre-extraction at 20-30℃ for 20-30 min, followed by main extraction at 50-60℃ for 40-60 min.

4. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S2, the weight ratio of coffee powder to water is 1:(4-6).

5. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S2, the mass of the complex enzyme is 0.15-0.2% of the mass of the coffee powder, and the mass ratio of the cellulase to the mannanase is (3-5):

1.

6. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S3, the molecular weight cutoff of the ultrafiltration membrane is 10,000-30,000 Da.

7. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S4, the temperature of the entire vacuum concentration process is ≤35℃.

8. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S5, the condensation temperature is -2~0℃.

9. The method for preparing ultra-concentrated coffee liquid according to claim 1, characterized in that, In step S5, mixing is carried out by high-pressure homogenization, the pressure of which is 30-40 MPa and the temperature of which is 10-15℃.

10. An ultra-strong coffee liquid obtained by the method for preparing ultra-strong coffee liquid according to any one of claims 1-9.

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