A decaffeination formula and process for low caffeine coffee beans

Abstract

This invention relates to the field of food processing technology, and in particular to a dedecanoate formulation and processing method for low-caffeine coffee beans. The formulation is a compound dedecanoate solution: 10–18 parts of food-grade ethanol, 0.5–1.2 parts of food-grade acetic acid, 0.3–0.8 parts of citric acid, 0.1–0.3 parts of green tea extract, 0.2–0.5 parts of 1000-mesh activated carbon powder, 80–90 parts of deionized water, 0.05–0.2 parts of guarana polysaccharide, 0.1–0.3 parts of inulin, 0.02–0.08 parts of rosmarinic acid, 0.2–0.6 parts of γ-cyclodextrin, 0.5–1.5 parts of erythritol, 0.05–0.15 parts of phytosterol, 0.1–0.4 parts of potassium citrate, and 0.05–0.2 parts of sodium lactate. The decaffeination formula and processing method for this low-caffeine coffee bean achieves a caffeine removal rate of ≥98.5% and a finished product caffeine content of ≤0.1% through the synergistic effect of natural chelation and gentle pore opening components of the compound decaffeination liquid, combined with a gradient negative pressure-pulse extraction process, which is far superior to the industry standard.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a decaffeination formula and processing method for low-caffeine coffee beans. Background Technology

[0002] Decacaffeine-free coffee beans, which balance coffee flavor and health needs, are experiencing continuous market demand growth. Existing decaffeination technologies for coffee beans mainly include the dichloromethane solvent method, the ethyl acetate method, the supercritical CO2 method for food processing, and the Swiss water treatment method. However, all have significant drawbacks: the solvent method, while lower in cost, carries the risk of organic solvent residue and easily damages flavor compounds such as chlorogenic acid and aroma precursors, resulting in a cardboard or boiled taste in the finished product; the supercritical CO2 method for food processing achieves high decaffeination rates and leaves no residue, but requires huge equipment investment and has high operating costs, making it difficult to achieve small- to medium-scale industrial production; the traditional Swiss water treatment method is a green process, but its decaffeination efficiency is low, with a caffeine removal rate typically only 85%-90% of that in food processing, and a large amount of aroma compounds are lost during the decaffeination process, resulting in a weak flavor in the finished product. To address the aforementioned issues, existing technologies attempt to optimize decaffeination solvents or process parameters, such as using a mixed solvent of ethanol and water to replace toxic solvents, or reducing flavor loss through low-temperature extraction. However, these approaches still suffer from the following shortcomings: First, decaffeination selectivity is poor, easily taking away flavor compounds while removing caffeine; second, aroma retention is insufficient, making it difficult to achieve the flavor level of regular coffee; third, the cell wall structure of coffee beans is easily damaged during decaffeination, leading to a deterioration in taste after roasting; and fourth, process stability is insufficient, resulting in significant batch-to-batch product quality variations. Therefore, developing a decaffeination formula and processing method that combines high decaffeination rate, high aroma retention, environmental safety, and reasonable cost has become a pressing technical challenge in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a decaffeination formulation and processing method for low-caffeine coffee beans to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a decaffeination formula for low-caffeine coffee beans, wherein the formula is a compound decaffeination liquid, comprising the following components by weight: Food-grade ethanol: 10–18 parts Food-grade acetic acid: 0.5–1.2 parts Citric acid: 0.3–0.8 parts Green tea extract (tea polyphenols ≥95%): 0.1–0.3 parts Activated carbon micro powder (1000 mesh): 0.2–0.5 parts Deionized water: 80–90 parts Natural chelated components: 0.05–0.2 parts guarana polysaccharide + 0.1–0.3 parts inulin Low-temperature fragrance stabilizer: 0.02–0.08 parts of rosmarinic acid (≥98%) + 0.2–0.6 parts of γ-cyclodextrin Mild pore-opening agent: 0.5–1.5 parts erythritol + 0.05–0.15 parts phytosterol In-situ acid-controlled buffer system: 0.1–0.4 parts potassium citrate + 0.05–0.2 parts sodium lactate The decaffeination process for low-caffeine coffee beans includes the following steps: S1: Green bean pretreatment; S2: Low-temperature enzymatic hydrolysis activation; S3: Gradient negative pressure-pulse synergistic degenerative extraction; S4: Desolventizing and desolderizing; S5: Aroma in-situ recovery - closed-loop replenishment; S6: Flavor recovery and stabilization; S7: Baking.

[0005] The gradient negative pressure-pulse synergistic degenerative extraction uses the composite degenerative solution described in claim 1.

[0006] Preferably, the raw bean pretreatment in S1 includes: rinsing with clean water 2–3 times at 30–35℃, pre-drying at 40–50℃ for 30–40 minutes until the moisture content is 10%–12%, and swelling with saturated steam at 75–85℃ for 15–25 minutes.

[0007] Preferably, the conditions for low-temperature enzymatic activation in S2 are as follows: adding compound enzyme solution at 0.3%–0.5% of the weight of raw beans, wherein the weight ratio of pectinase to cellulase in the compound enzyme solution is 1:2, and the enzyme activity is ≥10000U / g; enzymatic hydrolysis temperature is 40–45℃, pH is 4.5–5.5, and soaking is carried out in the dark for 30–60 minutes.

[0008] Preferably, the specific operation of gradient negative pressure-pulse synergistic degenerative extraction in S3 is as follows: S3.1: Add the compound degenerative solution at a material-to-liquid ratio of 1:8–1:12 (g / mL); S3.2: Evacuate to -0.04 to -0.06 MPa and maintain for 3 to 5 minutes; S3.3: Restore to normal pressure and maintain for 10–20 seconds; S3.4: Evacuate again to -0.02 to -0.03 MPa and maintain for 5 to 8 minutes; S3.5: Repeat steps S3.2-S3.43 to 5 times to form a gradient negative pressure-pulse cycle; S3.6: Extraction temperature control: 50–55℃ for the first 2 cycles, 60–65℃ for the next 2–3 cycles, with a stirring speed of 30–50 r / min throughout the process; S3.7: During the extraction process, the decaffeinated liquid is continuously filtered through a circulating filtration system to achieve online caffeine adsorption.

[0009] Preferably, the specific operation of aroma in-situ recovery-closed-loop replenishment in step S5 is as follows: S5.1: During the decenolysis and desolventization process, coffee aroma components are collected by a 0-5℃ low-temperature condensation trapping device to form a natural coffee aroma base liquid; S5.2: Under vacuum conditions of 30–45℃ and -0.07–-0.08MPa, the flavor base liquid is sprayed onto the surface of coffee beans with an atomized particle size of 5–10μm, and the spraying amount is 1%–2% of the weight of coffee beans; S5.3: Maintain a vacuum state for 15–20 minutes to allow aroma substances to penetrate into the coffee beans.

[0010] Preferably, the desolventizing and desolventizing in step S4 includes: centrifugation at 800–1000 r / min for 5–8 min, followed by hot air drying at 70–75°C for 10–15 min, ensuring that the residual solvent content is ≤0.001%.

[0011] Preferably, the flavor recovery and stabilization in S6 includes: spraying 3%–5% of the coffee bean weight of coffee aroma recovery liquid, vacuum drying at 55–60°C for 20–30 min to a moisture content of 9%–11%, and nitrogen-filled and sealed for temporary storage for 12–24 h.

[0012] Preferably, the baking in S7 is a three-stage temperature-controlled baking: the first stage is to raise the temperature from room temperature to 160°C at a rate of 5–8°C / min and hold for 10 min; the second stage is to raise the temperature from 160°C to 190°C at a rate of 2–3°C / min and hold for 15–20 min; and the third stage is to raise the temperature from 190°C to 205–210°C and hold for 5–8 min.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This low-caffeine coffee bean decaffeination formula and processing method achieves a caffeine removal rate of ≥98.5% and a finished product caffeine content of ≤0.1% through the synergistic effect of natural chelation and gentle pore opening components of the compound decaffeination solution, combined with a gradient negative pressure-pulse extraction process, which is far superior to the industry standard. Moreover, the entire formula uses food-grade components, and the residual amount after solvent removal is ≤0.001%, with no toxic organic solvents added, meeting food safety production requirements and solving the problems of residual risks in traditional solvent methods and low decaffeination efficiency in water treatment methods.

[0014] 2. The decaffeination formula and processing method for this low-caffeine coffee bean utilizes the antioxidant and molecular encapsulation aroma-protecting design of rosmarinic acid and γ-cyclodextrin, combined with an in-situ aroma recovery and closed-loop replenishment process, to achieve an aroma retention rate of ≥94%, avoiding the cardboard and boiled tastes that are easily produced during the decaffeination process. At the same time, the acid-controlling buffer system of potassium citrate and sodium lactate stabilizes the natural weakly acidic range of coffee. Combined with low-temperature enzymatic hydrolysis, segmented temperature-controlled extraction and roasting processes, it maximizes the retention of flavor substances such as chlorogenic acid and oils. The acidity and body of the finished product are ≥90% similar to ordinary decaffeinated coffee, demonstrating excellent stability.

[0015] 3. Compared to supercritical CO2 decaffeination technology, this low-caffeine coffee bean decaffeination formula and processing method significantly reduces equipment investment and operating costs. It eliminates the need for complex high-pressure equipment, and the gradient negative pressure-pulse extraction process shortens the decaffeination time and improves production efficiency. At the same time, the parameters of each process step are clear and the operation is controllable, enabling continuous and large-scale production from green bean pretreatment to finished product packaging. It is suitable for large coffee processing enterprises as well as small and medium-sized production needs, solving the industry pain points of high cost of traditional high-end decaffeination technology and significant flavor loss of conventional processes. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the preparation process of the decaffeinated coffee bean formulation of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1This invention provides a technical solution: a decaffeination formula for low-caffeine coffee beans, the formula being a compound decaffeination solution comprising the following components by weight: 10–18 parts of food-grade ethanol, 0.5–1.2 parts of food-grade acetic acid, 0.3–0.8 parts of citric acid, 0.1–0.3 parts of green tea extract, 0.2–0.5 parts of 1000-mesh activated carbon powder, 80–90 parts of deionized water, 0.05–0.2 parts of guarana polysaccharide, 0.1–0.3 parts of inulin, 0.02–0.08 parts of rosmarinic acid, 0.2–0.6 parts of γ-cyclodextrin, 0.5–1.5 parts of erythritol, 0.05–0.15 parts of phytosterol, 0.1–0.4 parts of potassium citrate, and 0.05–0.2 parts of sodium lactate.

[0020] Food-grade ethanol and food-grade acetic acid work synergistically to selectively dissolve caffeine, and the solubility changes with the temperature gradient to achieve segmented extraction. Citric acid adjusts the initial pH of the system, enhancing caffeine solubility; Tea polyphenols and rosmarinic acid form a complex antioxidant system that inhibits the oxidation of coffee oils and the degradation of flavor substances; Activated carbon micro powder adsorbs caffeine dissolved in the decaffeination solution in situ, preventing caffeine from being reabsorbed into the coffee beans; Guarana polysaccharide forms a natural high-molecular chelate structure with inulin, which specifically binds to the caffeine inside coffee beans and guides it to migrate to the decaffeination solution without reacting with chlorogenic acid or ester aroma substances. γ-cyclodextrin forms molecular encapsulation of coffee aroma substances, reducing aroma volatilization and loss during extraction; Erythritol and phytosterols act gently on the cell walls of coffee beans, opening micropores without damaging the cell structure, thereby improving caffeine diffusion efficiency and reducing extraction temperature and time. Potassium citrate and sodium lactate form a buffer pair to stabilize the pH of the system during decaffeination at 4.8–5.5 (the natural weakly acidic range of coffee), avoiding flavor deterioration and browning caused by excessive acidity or fluctuations.

[0021] The decaffeination process for low-caffeine coffee beans includes the following steps: S1: Green bean pretreatment; S2: Low-temperature enzymatic hydrolysis activation; S3: Gradient negative pressure-pulse synergistic degenerative extraction; S4: Desolventizing and desolderizing; S5: Aroma in-situ recovery - closed-loop replenishment; S6: Flavor recovery and stabilization; S7: Baking.

[0022] S1. Green Bean Pretreatment Select uniform, undamaged, and mold-free green coffee beans and rinse them 2-3 times with water at 30-35℃ to remove surface impurities. Place the rinsed green beans in a hot air dryer and pre-dry them at 40-50℃ for 30-40 minutes, controlling the moisture content of the green beans to 10%-12%. Then, put the pre-dried green beans into a steam expansion tank and introduce saturated steam at 75-85℃ for 15-25 minutes to initially loosen the cell walls of the coffee beans, laying the foundation for subsequent caffeine removal. S2. Low-temperature enzymatic activation After steam swelling, the green coffee beans are transferred to an enzymatic hydrolysis tank. A pectinase and cellulase complex solution (pectinase:cellulase = 1:2, enzyme activity ≥10000U / g) is added at 0.3%–0.5% of the weight of the green beans. The system temperature is adjusted to 40–45℃ and pH 4.5–5.5. The beans are soaked in the dark for 30–60 minutes. Enzymatic hydrolysis removes some of the pectin and cellulose on the surface of the coffee beans, further opens the cell wall channels, improves the efficiency of caffeine diffusion, and avoids the loss of flavor substances caused by high-temperature enzymatic hydrolysis. S3. Gradient negative pressure-pulse synergistic degenerative extraction After enzymatic hydrolysis, the raw soybeans are transferred to a sealed extraction tank. The above-mentioned compound degenerate solution is added at a material-to-liquid ratio of 1:8–1:12 (g / mL). The gradient negative pressure-pulse circulation and stirring system is then started. The specific operation is as follows: First stage: Evacuate to -0.04 to -0.06 MPa and maintain for 3 to 5 minutes to remove air from inside the coffee beans and the gaps in the extraction tank; Second stage: Quickly restore normal pressure and maintain it for 10-20 seconds, using the pressure difference to allow the decaffeination liquid to quickly penetrate into the micropores inside the coffee beans; Third stage: Evacuate again to -0.02 to -0.03 MPa and maintain for 5 to 8 minutes; Repeat the first to third stages above 3 to 5 times to form a gradient negative pressure-pulse cycle; Extraction temperature control: 50–55℃ for the first 2 cycles, and 60–65℃ for the next 2–3 cycles, with a stirring speed of 30–50 r / min throughout the process; During the extraction process, the decaffeinated liquid is continuously filtered through a built-in circulating filtration system in the extraction tank, and activated carbon micropowder is used to adsorb caffeine in the decaffeinated liquid online to prevent caffeine reabsorption. S4. Desolventizing and Removing Solvents After extraction, the coffee beans are separated from the decanoate and transferred to a centrifuge for 5–8 minutes at 800–1000 rpm to remove most of the decanoate adhering to the surface of the coffee beans. The centrifuged coffee beans are then sent to a hot air dryer and dried at 70–75°C for 10–15 minutes to remove residual ethanol and acetic acid from the inside of the coffee beans. After this step, the solvent residue in the coffee beans is ≤0.001%, which meets the food-grade safety standards. S5. Aroma In-situ Recovery - Closed-Loop Replenishment During step S3 (decyned extraction) and step S4 (hot air drying), the low-temperature condensation and collection device above the extraction tank and dryer is activated. The condensation temperature of the device is controlled at 0–5°C to continuously collect the volatile coffee aroma components (mainly aldehydes, esters, ketones, and other natural aroma substances) to form a natural coffee aroma base liquid. The desolventized coffee beans are transferred to a vacuum replenishment tank, which is evacuated to -0.07–-0.08 MPa. The temperature inside the tank is controlled at 30–45°C. The collected natural coffee aroma base liquid is evenly sprayed onto the surface of the coffee beans through a micron-level atomizing nozzle (atomizing particle size 5–10 μm), with a spray volume of 1%–2% of the coffee bean weight. The vacuum state is maintained for 15–20 minutes to allow the aroma substances to re-penetrate into the coffee beans, achieving in-situ aroma recovery and closed-loop replenishment, avoiding unnatural flavor problems caused by the addition of exogenous flavorings. S6. Flavor recovery and stabilization After vacuum replenishment, the coffee beans are sprayed with coffee aroma recovery liquid (extracted from green coffee beans by low-temperature distillation, with a solid content of 5%–8%), and the spray volume is 3%–5% of the weight of the coffee beans. The coffee beans are then transferred to a vacuum dryer and vacuum dried at 55–60℃ for 20–30 minutes, controlling the moisture content of the coffee beans to 9%–11%. After drying, the coffee beans are transferred to a nitrogen-filled and sealed temporary storage tank and stored for 12–24 hours to allow the flavor substances to be evenly distributed and improve the flavor stability of the product. S7. Baking and Finished Products The temporarily stored coffee beans are then fed into the roaster and roasted using a three-stage temperature control system. Heating phase: The room temperature is raised to 160℃ at a rate of 5–8℃ / min, and held for 10 minutes; Maillard reaction section: 160℃ to 190℃, heating rate 2–3℃ / min, hold for 15–20min; Caramelization reaction section: Increase from 190℃ to 205–210℃ and hold for 5–8 minutes; After roasting, the coffee beans are quickly cooled to room temperature, and broken or burnt beans are removed using a sorting machine. Finally, they are sealed in nitrogen-filled packaging to obtain the finished decaffeinated coffee beans.

[0023] Example 1

[0024] Compound Detoxification Solution Formula Food-grade ethanol 15 parts, food-grade acetic acid 0.8 parts, citric acid 0.5 parts, green tea extract (tea polyphenols ≥95%) 0.2 parts, activated carbon powder (1000 mesh) 0.3 parts, deionized water 85 parts, guarana polysaccharide 0.1 parts, inulin 0.2 parts, rosmarinic acid 0.05 parts, γ-cyclodextrin 0.4 parts, erythritol 1.0 part, phytosterol 0.1 parts, potassium citrate 0.2 parts, sodium lactate 0.1 parts. Treatment method. Green bean pretreatment: Selected Colombian green coffee beans are rinsed three times with water at 32℃, pre-dried at 45℃ for 35 minutes until the moisture content is 11%, and steam-swelled at 80℃ for 20 minutes. Low-temperature enzymatic activation: Add 0.4% of the weight of raw soybeans in a compound enzyme solution (pectinase: cellulase = 1:2), and soak at 42℃, pH 5.0, in the dark for 45 minutes; Gradient negative pressure-pulse extraction: material-liquid ratio 1:10 (g / mL), add compound degenerative solution, cycle 4 times (-0.05MPa for 4 min → atmospheric pressure for 15 s → -0.025MPa for 6 min), the first 2 cycles are at 52℃, the last 2 cycles are at 62℃, and the stirring speed is 40 r / min; Dehydration and solvent removal: Centrifuge at 900 r / min for 6 min, then dry with hot air at 72℃ for 12 min; Aroma in situ replenishment: The fragrance base liquid is captured by condensation at 0–5℃, and 1.5% fragrance base liquid is sprayed by atomization at 35℃ and -0.075MPa, followed by vacuum adsorption for 18 minutes; Flavor stabilization: Spray with 4% aroma recovery liquid, vacuum dry at 58℃ for 25 min to moisture content of 10%, and temporarily store under nitrogen for 18 h; Baking: 160℃ / 10min→190℃ / 18min→208℃ / 6min, cool, screen, and package. Test results The caffeine removal rate is 98.8%, the finished product has a caffeine content of 0.08% (dry basis), the aroma retention rate is 95.2%, there is no solvent residue, and the acidity and body are 92% similar to ordinary Colombian coffee.

[0025] Example 2

[0026] Compound Detoxification Solution Formula 12 parts of food-grade ethanol, 0.6 parts of food-grade acetic acid, 0.4 parts of citric acid, 0.15 parts of green tea extract (tea polyphenols ≥95%), 0.3 parts of activated carbon powder (1000 mesh), 88 parts of deionized water, 0.08 parts of guarana polysaccharide, 0.15 parts of inulin, 0.03 parts of rosmarinic acid, 0.3 parts of γ-cyclodextrin, 0.8 parts of erythritol, 0.08 parts of phytosterol, 0.15 parts of potassium citrate, and 0.08 parts of sodium lactate. processing method Green bean pretreatment: Selected Ethiopian green coffee beans are rinsed twice with water at 30℃, pre-dried at 42℃ for 30 minutes until the moisture content is 10.5%, and steam-swelled at 78℃ for 18 minutes. Low-temperature enzymatic activation: Add 0.3% of the weight of the raw soybeans in a compound enzyme solution, and soak at 40℃ and pH 4.8 in the dark for 40 minutes; Gradient negative pressure-pulse extraction: material-liquid ratio 1:9 (g / mL), add compound degenerate solution, cycle 3 times (-0.045MPa for 3 min → atmospheric pressure for 12 s → -0.02MPa for 5 min), the first cycle is at 50℃, the next two cycles are at 60℃, and the stirring speed is 35 r / min; Dehydration and solvent removal: Centrifuge at 850 r / min for 5 min, then dry with hot air at 70℃ for 10 min; Aroma replenishment in situ: The fragrance base liquid is captured by condensation at 0–5℃, and 1.2% fragrance base liquid is sprayed by atomization at 32℃ and -0.07MPa, followed by vacuum adsorption for 15 minutes; Flavor stabilization: Spray with 3.5% aroma recovery liquid, vacuum dry at 55℃ for 22 min to moisture content of 9.5%, and temporarily store under nitrogen for 15 h; Baking: 160℃ / 10min→190℃ / 16min→205℃ / 5min, cool, screen, and package. Test results The caffeine removal rate is 98.6%, the finished product has a caffeine content of 0.09% (dry basis), the aroma retention rate is 94.5%, there is no solvent residue, and the acidity and body are 91% similar to ordinary Ethiopian coffee.

[0027] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A decaffeinated coffee bean formulation, characterized in that: The formula is a compound detoxifying solution, comprising the following components by weight: 10–18 parts of food-grade ethanol, 0.5–1.2 parts of food-grade acetic acid, 0.3–0.8 parts of citric acid, 0.1–0.3 parts of green tea extract, 0.2–0.5 parts of 1000-mesh activated carbon powder, 80–90 parts of deionized water, 0.05–0.2 parts of guarana polysaccharide, 0.1–0.3 parts of inulin, 0.02–0.08 parts of rosmarinic acid, 0.2–0.6 parts of γ-cyclodextrin, 0.5–1.5 parts of erythritol, 0.05–0.15 parts of phytosterol, 0.1–0.4 parts of potassium citrate, and 0.05–0.2 parts of sodium lactate.

2. The method for decaffeination of low-caffeine coffee beans according to claim 1, characterized in that: The steps are as follows: S1: Green bean pretreatment; S2: Low-temperature enzymatic hydrolysis activation; S3: Gradient negative pressure-pulse synergistic degenerative extraction; S4: Desolventizing and desolderizing; S5: Aroma in-situ recovery - closed-loop replenishment; S6: Flavor recovery and stabilization; S7: Baking; The gradient negative pressure-pulse synergistic degenerative extraction uses the composite degenerative solution described in claim 1.

3. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The pretreatment of raw beans in S1 includes: rinsing with clean water 2–3 times at 30–35℃, pre-drying at 40–50℃ for 30–40 minutes until the moisture content is 10%–12%, and swelling with saturated steam at 75–85℃ for 15–25 minutes.

4. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The conditions for low-temperature enzymatic activation in S2 are as follows: add compound enzyme solution at 0.3%–0.5% of the weight of raw soybeans, wherein the weight ratio of pectinase to cellulase in the compound enzyme solution is 1:2, and the enzyme activity is ≥10000U / g; enzymatic hydrolysis temperature is 40–45℃, pH is 4.5–5.5, and soaking is carried out in the dark for 30–60 minutes.

5. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The specific operation of gradient negative pressure-pulse synergistic degenerative extraction in S3 is as follows: S3.1: Add the compound degenerative solution at a material-to-liquid ratio of 1:8–1:12 (g / mL); S3.2: Evacuate to -0.04 to -0.06 MPa and maintain for 3 to 5 minutes; S3.3: Restore to normal pressure and maintain for 10–20 seconds; S3.4: Evacuate again to -0.02 to -0.03 MPa and maintain for 5 to 8 minutes; S3.5: Repeat steps S3.2-S3.43 to 5 times to form a gradient negative pressure-pulse cycle; S3.6: Extraction temperature control: 50–55℃ for the first 2 cycles, 60–65℃ for the next 2–3 cycles, with a stirring speed of 30–50 r / min throughout the process; S3.7: During the extraction process, the decaffeinated liquid is continuously filtered through a circulating filtration system to achieve online caffeine adsorption.

6. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The specific operation of aroma in-situ recovery and closed-loop replenishment in S5 is as follows: S5.1: During the decenolysis and desolventization process, coffee aroma components are collected by a 0-5℃ low-temperature condensation trapping device to form a natural coffee aroma base liquid; S5.2: Under vacuum conditions of 30–45℃ and -0.07–-0.08MPa, the flavor base liquid is sprayed onto the surface of coffee beans with an atomized particle size of 5–10μm, and the spraying amount is 1%–2% of the weight of coffee beans; S5.3: Maintain a vacuum state for 15–20 minutes to allow aroma substances to penetrate into the coffee beans.

7. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The desolventizing and desolderizing process in S4 includes: centrifugation at 800–1000 r / min for 5–8 min, followed by hot air drying at 70–75℃ for 10–15 min, ensuring that the residual solvent content is ≤0.001%.

8. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The flavor recovery and stabilization in S6 includes: spraying 3%–5% of the coffee bean weight of coffee aroma recovery liquid, vacuum drying at 55–60℃ for 20–30 min to a moisture content of 9%–11%, and nitrogen-filled and sealed for temporary storage for 12–24 h.

9. The method for decaffeination of low-caffeine coffee beans according to claim 2, characterized in that: The baking process in S7 is a three-stage temperature-controlled baking: the first stage is to raise the temperature from room temperature to 160°C at a rate of 5–8°C / min and hold for 10 min; the second stage is to raise the temperature from 160°C to 190°C at a rate of 2–3°C / min and hold for 15–20 min; and the third stage is to raise the temperature from 190°C to 205–210°C and hold for 5–8 min.

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