Pu'er tea enzyme powder and preparation method thereof

Abstract

The invention relates to the technical field of tea enzyme preparation, in particular to a Pu'er tea enzyme powder preparation method which comprises the steps of tea leaf pretreatment, fermentation liquor preparation, fermentation liquor filtration and drying for powder preparation. According to the Pu'er tea enzyme powder and the preparation method thereof, the Pu'er raw tea leaves, the sugar source, the EM bacterial powder, the citrus peel particles and the lemon peel particles are taken as raw materials, so that the flavor and the enzyme activity can be enhanced, multi-stage synergistic fermentation is realized, flora proliferation is promoted through natural fructose and cellulose, and the enzyme activity and the organic acid yield are improved; by combining the whole fermentation period, matched control of exhaust and pH value monitoring is realized according to flora activity in different stages, and the problem of out-of-control fermentation or infectious microbe pollution can be avoided; through high-pressure sterilization gauze filtration, pasteurization and centrifugal layering plate-frame pressure filtration treatment, the purity of a stock solution can be effectively guaranteed, and the survival rate of active ingredients such as enzymes, probiotics and polyphenols in the enzyme powder is effectively increased by adopting a low-temperature concentration and freeze-drying process.

Description

Technical Field

[0001] This invention relates to the field of tea enzyme preparation technology, specifically to a Pu-erh tea enzyme powder and its preparation method. Background Technology

[0002] Pu-erh tea enzyme powder is a functional powder product made from Pu-erh tea as the main raw material through microbial fermentation technology. It combines the active ingredients of Pu-erh tea itself with the probiotics, enzymes, organic acids and other metabolites produced during the fermentation process, and has compound nutritional value and health benefits.

[0003] A search revealed that Chinese Patent Publication No. CN103766526A discloses a Pu-erh tea enzyme powder and its preparation method. The Pu-erh tea enzyme powder in this invention patent is prepared using Pu-erh tea, probiotic fermentation agent, and xylitol as raw materials. It is rich in functional factors such as tea polyphenols, caffeine, and tea saponins. The enzyme is obtained through natural fermentation using a natural probiotic fermentation agent. The product is rich in various tea enzymes and can enhance metabolism, lower lipids, aid weight loss, and calm and lower blood pressure.

[0004] However, the strains and raw materials used in the preparation method of Pu'er tea enzyme powder are relatively simple, lacking optimization of flavor and fermentation efficiency. Furthermore, the lack of process control during sealed fermentation can easily lead to uneven fermentation or uncontrollable metabolites. Additionally, there are issues that need further improvement in sterilization and impurity filtration control. Therefore, a method for preparing Pu'er tea enzyme powder and its preparation method is proposed. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a Pu-erh tea enzyme powder and its preparation method, which has the advantages of optimizing fermentation efficiency and strictly controlling the fermentation process and sterilization and impurity removal process. It solves the problems in the existing Pu-erh tea enzyme powder preparation methods mentioned above, such as uncontrollable fermentation process, which easily leads to uneven fermentation or uncontrollable metabolites, and the need to further improve the control of sterilization and impurity removal process.

[0007] (II) Technical Solution

[0008] To achieve the above-mentioned goals of optimizing fermentation efficiency and strictly controlling the fermentation process and sterilization and impurity removal process, the present invention provides the following technical solution: a Pu-erh tea enzyme powder, comprising enzyme preparation raw materials composed of 100 parts of raw Pu-erh tea leaves, 100-150 parts of sugar source, 1-2 parts of fermentation strain, 450-550 parts of purified water and 15-25 parts of auxiliary materials in the following mass proportions.

[0009] A method for preparing Pu-erh tea enzyme powder includes the following steps:

[0010] S1. Tea pretreatment: Soak the tea leaves in warm water at 35-45℃ for 4-6 minutes, and wash them one to three times to remove dust and impurities. Sterilize them in a microwave drying and sterilizing machine for a certain period of time, and then grind them in a pulverizer to obtain Pu'er tea powder. Sieve the powder through an 80-mesh sieve for later use.

[0011] S2. Preparation of fermentation liquid: Select a quantitative sugar source, add it to the fermentation tank, add the proportion of purified water and stir to dissolve it completely. Then add the proportion of Pu'er tea powder and auxiliary materials and stir for 2-4 minutes. Add an appropriate amount of fermentation bacteria to the obtained mixture, seal and store it. Place the fermentation tank in a room temperature and light-proof environment for fermentation reaction.

[0012] S3. Fermentation liquid filtration: The fermentation liquid residue is filtered through sterilized gauze cooked in a high-pressure sterilizer to obtain Pu'er tea enzyme stock solution. The enzyme stock solution is then treated with pasteurization to inactivate miscellaneous bacteria and concentrated under reduced pressure to a soluble semi-solid structure.

[0013] S4. Drying and pulverizing: After adding maltodextrin in proportion and stirring evenly, enzyme powder is prepared by freeze drying.

[0014] Preferably, the specific steps of the pretreatment of raw Pu'er tea leaves in step S1 include:

[0015] 1) Select a clean measuring cup and put in an appropriate amount of raw tea leaves. Add water slowly along the cup wall at a tea-to-water ratio of 1:50 to fully soak the tea leaves. Use a glass rod to slowly stir the soaking water for 1-2 minutes to ensure that the tea leaves fully unfurl.

[0016] 2) Let it stand and continue to soak for 3-4 minutes. Tilt the cup wall and slowly pour out the turbid soaking liquid. Depending on the turbidity of the soaking liquid, wash the tea leaves one to three times. Take out the tea leaves and spread them flat on a dry and clean filter cloth. Place them in a ventilated and cool place for 1-1.5 hours to drain the water.

[0017] 3) Spread the damp tea leaves evenly in a ceramic ware and put it into a microwave dryer. First, set the low heat mode to preheat the ceramic ware for 1 to 2 minutes, and then turn on the medium-high heat mode to sterilize and dry for 3 to 4 minutes. On the high heat mode, stir-fry and turn the tea leaves over once every 30 seconds.

[0018] 4) Use a tea needle to crush Pu'er tea leaves into 1-2cm pieces, then put them into a pulverizer for primary crushing and fine crushing. During the primary crushing process, set the crushing temperature to ≤45℃, crush for 10 seconds each time and cool for 1 minute in between, sieve through a 40-mesh sieve, and re-crush any unqualified particles.

[0019] 5) During fine grinding, grind for 2 minutes each time and cool for 1 minute at intervals. Check the fineness of the grinding. After passing through an 80-mesh sieve, discharge the material and seal it with nitrogen for later use.

[0020] Preferably, the sugar source in step S2 is selected from brown sugar, black sugar and honey, the auxiliary material is composed of 45% citrus peel particles and 55% lemon peel particles in each proportion, and the fermentation strain is EM powder.

[0021] 5. The Pu-erh tea enzyme powder and its preparation method according to claim 2, characterized in that the specific steps for preparing the fermentation liquid include;

[0022] 1) Add the measured sugar source and purified water to the fermentation tank at a ratio of 1:(4.5~5.5), and stir at a speed of 200~650rpm for 10min to ensure that the sugar source is fully dissolved to obtain a syrup solution;

[0023] 2) Add Pu-erh tea powder and auxiliary materials to the syrup solution at a ratio of (4-5):1, and continue to stir at a speed of 500-1100 rpm for 2-4 minutes. After mixing thoroughly, add the fermentation starter, place it in a room temperature dark environment and seal it for reaction, and control the fermentation temperature in the tank to 25-30℃.

[0024] 3) Set the total fermentation time to 7-10 days. During the first 1-3 days of the reaction, the yeast is more active and produces CO2, accompanied by the generation of bubbles. At this time, the pH value of the fermentation liquid is ≤4.0. For the first three days, it is necessary to release CO2 by venting once a day.

[0025] 4) During the 4th to 7th day of the reaction, lactic acid bacteria are more active and organic acids and enzymes are produced. At this time, the pH value of the fermentation broth is 3.8 to 4.2.

[0026] 5) During the 8-10 day reaction, the pH value of the fermentation liquid is ≤4.0 and no bubbles are produced. The aroma of wine or fruit acid is released and the fermentation liquid is brownish-brown.

[0027] Preferably, the specific steps of the fermentation broth filtration include:

[0028] 1) Set the cooking temperature of the high-pressure sterilizer to 121.3℃ and the pressure to 103.4kPa. Cook the sterilized gauze for 20-30 minutes to ensure thorough sterilization. After sterilization, filter out the fermentation liquid residue with the sterilized gauze to obtain the enzyme stock solution.

[0029] 2) The liquid and tiny suspended particles in the enzyme stock solution are separated by centrifugation in a centrifuge, and the separated solid-liquid mixture is then separated by a plate and frame filter press.

[0030] 3) Continue to pass the enzyme stock solution into the pasteurization device and heat it at a temperature of 68-75°C for 0.5-1 hour. Then, quickly cool the sterilized enzyme stock solution to 4-5°C and keep it at that temperature for 15-25 minutes.

[0031] 4) Pass the sterilized fermentation broth into the rotary evaporator flask, start the vacuum pump and gradually reduce the internal pressure of the flask until the target vacuum degree is reached, which is about 0.05 to 0.08 MPa, and lower the boiling point of the liquid to 40 to 60°C.

[0032] 5) Control the water bath temperature of the rotary evaporator flask at 50-70℃ and rotate or stir at 400-1100 rpm to accelerate the uniform evaporation of the enzyme stock solution and prevent local overheating and coking. Use a hydrometer to measure the specific gravity to determine the concentration endpoint and concentrate to a viscous semi-solid state with a solid content of 40-50%.

[0033] Preferably, the specific steps of the drying and powdering process include:

[0034] 1) Mix maltodextrin and concentrated enzyme stock solution in a 1:1 mass ratio and stir for 10 minutes, then add mannitol at a concentration of 1-5% as a freeze-drying protectant.

[0035] 2) Dispense the concentrated enzyme stock solution evenly into the freeze-drying tray, controlling the thickness to ≤1cm. Place the sample in ultra-low temperature liquid nitrogen at -40 to -80℃ for pre-freezing treatment for 2 to 4 hours to form fine ice crystals and ensure that the sample is completely frozen into a solid state.

[0036] 3) Start the freeze dryer to reduce the vacuum to 10-50 Pa, and slowly raise the shelf temperature to -20-0℃. Close the valve between the sample chamber and the cold trap, and keep the cold trap temperature ≤-50℃ for 12-48 hours to capture sublimated water vapor until more than 90% of the free water sublimates.

[0037] 4) Gradually increase the shelf temperature to 20-30℃ to remove bound water and maintain a vacuum of ≤10Pa for 4-12 hours. When the sample temperature and shelf temperature are close to the same, turn off the vacuum pump and wait for the pressure to stabilize to complete the drying process.

[0038] 5) Turn off the vacuum pump, fill the freeze-drying chamber with nitrogen and quickly remove the freeze-dried enzyme powder. Gently crush the freeze-dried block with a sterile pulverizer, sieve it through an 80-100 mesh sieve, and then seal it in a light-proof and moisture-proof container for freezing storage at -20°C.

[0039] (III) Beneficial Effects

[0040] Compared with the prior art, the present invention provides a Pu-erh tea enzyme powder and its preparation method, which has the following beneficial effects:

[0041] 1. This Pu-erh tea enzyme powder and its preparation method use raw Pu-erh tea leaves, sugar source, EM bacteria powder, and citrus peel particles and lemon peel particles as raw materials to enhance flavor and enzyme activity to achieve multi-stage synergistic fermentation. The natural fructose and cellulose in the peel promote the proliferation of microorganisms, increase enzyme activity and organic acid production, thereby effectively improving fermentation efficiency.

[0042] 2. This Pu-erh tea enzyme powder and its preparation method, by combining the entire fermentation cycle and according to the activity of the microbial community at different stages, achieve gas degassing and pH monitoring and control, thereby avoiding problems such as fermentation runaway or contamination by miscellaneous bacteria.

[0043] 3. The Pu-erh tea enzyme powder and its preparation method, through multiple purification steps such as high-pressure sterilization gauze filtration, pasteurization and centrifugal layered plate and frame filtration, can effectively ensure the purity of the original liquid. The low-temperature concentration and freeze-drying process effectively improves the survival rate of active ingredients such as enzymes, probiotics and polyphenols in the enzyme powder. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and 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.

[0046] Example 1

[0047] In this embodiment, 100 parts of raw Pu-erh tea leaves, 100 parts of sugar source, 1 part of fermentation starter, 450 parts of purified water, and 36 parts of citrus peel particles and 44 parts of lemon peel particles were selected as raw materials for enzyme preparation. The preparation steps include:

[0048] L1. Preparation of fermentation liquid: Select 100 parts of sugar source and add 450 parts of purified water to the fermentation tank and stir at 200-650 rpm for 10 minutes to ensure that the sugar source is fully dissolved to obtain a syrup solution. Then add 100 parts of Pu-erh tea powder prepared from raw Pu-erh tea leaves, and mix with 36 parts of citrus peel particles and 44 parts of lemon peel particles at 500-1100 rpm for 2-4 minutes. Add 1 part of fermentation inoculum to the obtained mixture and seal it. Place the fermentation tank in a room temperature and light-proof environment for fermentation reaction, control the fermentation temperature in the tank at 25-30℃, and the total fermentation time is 7-10 days.

[0049] During the first three days of the reaction, the yeast is more active and produces CO2, accompanied by the generation of bubbles. At this time, the pH value of the fermentation liquid is ≤4.0. For the first three days, it is necessary to release CO2 by venting once a day.

[0050] During the 4th to 7th day of the reaction, lactic acid bacteria are more active and produce organic acids and enzymes. At this time, the pH value of the fermentation broth is 3.8 to 4.2.

[0051] During the 8-10 day reaction, the pH value of the fermentation liquid is ≤4.0 and no bubbles are produced. Accompanied by the volatilization of wine aroma or fruit acid aroma, the fermentation liquid is brownish-brown.

[0052] L2. Fermentation liquid filtration: Set the cooking temperature of the high-pressure sterilizer to 121.3℃ and the pressure to 103.4kPa. Sterilize the gauze for 20-30 minutes to ensure thorough sterilization. Filter the fermentation liquid residue through the sterilized gauze to obtain Pu'er tea enzyme stock solution. Centrifuge the liquid and small suspended particles in the enzyme stock solution to separate them. Separate the solid-liquid mixture by using a plate and frame filter press. Continue to pass the enzyme stock solution into the pasteurization device and heat it at 68-75℃ for 0.5-1 hour. Then, quickly cool the sterilized enzyme stock solution to 4-5℃ and keep it at that temperature for 15-25 minutes.

[0053] The sterilized fermentation broth is passed into a rotary evaporator flask, and the vacuum pump is started to gradually reduce the internal pressure of the flask until the target vacuum level is reached, which is about 0.05 to 0.08 MPa, and the boiling point of the liquid is lowered to 40 to 60°C.

[0054] The water bath temperature of the rotary evaporator flask is controlled at 50-70℃, and the flask is rotated or stirred at 400-1100 rpm to accelerate the uniform evaporation of the enzyme stock solution and prevent local overheating and coking. The specific gravity is measured with a hydrometer to determine the concentration endpoint, and the solution is concentrated to a viscous semi-solid state with a solid content of 40-50%.

[0055] L3. Drying and pulverizing: Mix maltodextrin and concentrated enzyme stock solution in a 1:1 mass ratio and stir for 10 min. Add mannitol at a concentration of 1-5% as a freeze-drying protectant. Dispense the concentrated enzyme stock solution evenly into freeze-drying trays, controlling the thickness to ≤1 cm. Place the sample in ultra-low temperature liquid nitrogen at -40 to -80℃ for pre-freezing treatment for 2-4 h to ensure that the sample is completely frozen into a solid state.

[0056] Start the freeze dryer and reduce the vacuum to 10-50 Pa. Slowly raise the shelf temperature to -20-0°C and maintain the cold trap temperature ≤-50°C for 12-48 hours until more than 90% of the free water sublimates. Then gradually raise the shelf temperature to 20-30°C to remove bound water and maintain the vacuum at ≤10 Pa for 4-12 hours. When the sample temperature and shelf temperature are close to the same, turn off the vacuum pump and wait for the pressure to stabilize to complete the drying process.

[0057] Turn off the vacuum pump, fill the freeze-drying chamber with nitrogen, and quickly remove the freeze-dried enzyme powder. Gently crush the freeze-dried blocky material with a sterile pulverizer, sieve it through an 80-100 mesh sieve, and then seal it in a light-proof and moisture-proof container for freezing and storage at -20°C.

[0058] Example 2

[0059] In this embodiment, 100 parts of raw Pu-erh tea leaves, 125 parts of sugar source, 1.5 parts of fermentation starter, 500 parts of purified water, and 100 parts of auxiliary materials were selected as raw materials for enzyme preparation. The preparation steps include:

[0060] L1. Preparation of Fermentation Liquid: Select 125 parts of sugar source and add 500 parts of purified water to the fermentation tank and stir at 200-650 rpm for 10 minutes to ensure that the sugar source is fully dissolved to obtain a syrup solution. Then add 100 parts of Pu-erh tea powder prepared from raw Pu-erh tea leaves, and mix with 45 parts of citrus peel particles and 55 parts of lemon peel particles at 500-1100 rpm for 2-4 minutes. Add 1.5 parts of fermentation inoculum to the resulting mixture and seal it. Place the fermentation tank in a room temperature and light-proof environment for fermentation reaction, control the fermentation temperature in the tank at 25-30℃, and the total fermentation time is 7-10 days.

[0061] During the first three days of the reaction, the yeast is more active and produces CO2, accompanied by the generation of bubbles. At this time, the pH value of the fermentation liquid is ≤4.0. For the first three days, it is necessary to release CO2 by venting once a day.

[0062] During the 4th to 7th day of the reaction, lactic acid bacteria are more active and produce organic acids and enzymes. At this time, the pH value of the fermentation broth is 3.8 to 4.2.

[0063] During the 8-10 day reaction, the pH value of the fermentation liquid is ≤4.0 and no bubbles are produced. Accompanied by the volatilization of wine aroma or fruit acid aroma, the fermentation liquid is brownish-brown.

[0064] L2. Fermentation liquid filtration: Set the cooking temperature of the high-pressure sterilizer to 121.3℃ and the pressure to 103.4kPa. Sterilize the gauze for 20-30 minutes to ensure thorough sterilization. Filter the fermentation liquid residue through the sterilized gauze to obtain Pu'er tea enzyme stock solution. Centrifuge the liquid and small suspended particles in the enzyme stock solution to separate them. Separate the solid-liquid mixture by using a plate and frame filter press. Continue to pass the enzyme stock solution into the pasteurization device and heat it at 68-75℃ for 0.5-1 hour. Then, quickly cool the sterilized enzyme stock solution to 4-5℃ and keep it at that temperature for 15-25 minutes.

[0065] The sterilized fermentation broth is passed into a rotary evaporator flask, and the vacuum pump is started to gradually reduce the internal pressure of the flask until the target vacuum level is reached, which is about 0.05 to 0.08 MPa, and the boiling point of the liquid is lowered to 40 to 60°C.

[0066] The water bath temperature of the rotary evaporator flask is controlled at 50-70℃, and the flask is rotated or stirred at 400-1100 rpm to accelerate the uniform evaporation of the enzyme stock solution and prevent local overheating and coking. The specific gravity is measured with a hydrometer to determine the concentration endpoint, and the solution is concentrated to a viscous semi-solid state with a solid content of 40-50%.

[0067] L3. Drying and pulverizing: Mix maltodextrin and concentrated enzyme stock solution in a 1:1 mass ratio and stir for 10 min. Add mannitol at a concentration of 1-5% as a freeze-drying protectant. Dispense the concentrated enzyme stock solution evenly into freeze-drying trays, controlling the thickness to ≤1 cm. Place the sample in ultra-low temperature liquid nitrogen at -40 to -80℃ for pre-freezing treatment for 2-4 h to ensure that the sample is completely frozen into a solid state.

[0068] Start the freeze dryer and reduce the vacuum to 10-50 Pa. Slowly raise the shelf temperature to -20-0°C and maintain the cold trap temperature ≤-50°C for 12-48 hours until more than 90% of the free water sublimates. Then gradually raise the shelf temperature to 20-30°C to remove bound water and maintain the vacuum at ≤10 Pa for 4-12 hours. When the sample temperature and shelf temperature are close to the same, turn off the vacuum pump and wait for the pressure to stabilize to complete the drying process.

[0069] Turn off the vacuum pump, fill the freeze-drying chamber with nitrogen, and quickly remove the freeze-dried enzyme powder. Gently crush the freeze-dried blocky material with a sterile pulverizer, sieve it through an 80-100 mesh sieve, and then seal it in a light-proof and moisture-proof container for freezing and storage at -20°C.

[0070] Example 3

[0071] In this embodiment, 100 parts of raw Pu-erh tea leaves, 150 parts of sugar source, 2 parts of fermentation starter, 550 parts of purified water, and 120 parts of auxiliary materials were selected as raw materials for enzyme preparation. The preparation steps include:

[0072] L1. Preparation of fermentation liquid: Select 150 parts of sugar source and add 550 parts of purified water to the fermentation tank and stir at 200-650 rpm for 10 minutes to ensure that the sugar source is fully dissolved to obtain a syrup solution. Then add 100 parts of Pu-erh tea powder prepared from raw Pu-erh tea leaves, and mix with 54 parts of citrus peel particles and 66 parts of lemon peel particles at 500-1100 rpm for 2-4 minutes. Add 2 parts of fermentation inoculum to the obtained mixture and seal it. Place the fermentation tank in a room temperature and light-proof environment for fermentation reaction. Control the fermentation temperature in the tank at 25-30℃. The total fermentation time is 7-10 days.

[0073] During the first three days of the reaction, the yeast is more active and produces CO2, accompanied by the generation of bubbles. At this time, the pH value of the fermentation liquid is ≤4.0. For the first three days, it is necessary to release CO2 by venting once a day.

[0074] During the 4th to 7th day of the reaction, lactic acid bacteria are more active and produce organic acids and enzymes. At this time, the pH value of the fermentation broth is 3.8 to 4.2.

[0075] During the 8-10 day reaction, the pH value of the fermentation liquid is ≤4.0 and no bubbles are produced. Accompanied by the volatilization of wine aroma or fruit acid aroma, the fermentation liquid is brownish-brown.

[0076] L2. Fermentation liquid filtration: Set the cooking temperature of the high-pressure sterilizer to 121.3℃ and the pressure to 103.4kPa. Sterilize the gauze for 20-30 minutes to ensure thorough sterilization. Filter the fermentation liquid residue through the sterilized gauze to obtain Pu'er tea enzyme stock solution. Centrifuge the liquid and small suspended particles in the enzyme stock solution to separate them. Separate the solid-liquid mixture by using a plate and frame filter press. Continue to pass the enzyme stock solution into the pasteurization device and heat it at 68-75℃ for 0.5-1 hour. Then, quickly cool the sterilized enzyme stock solution to 4-5℃ and keep it at that temperature for 15-25 minutes.

[0077] The sterilized fermentation broth is passed into a rotary evaporator flask, and the vacuum pump is started to gradually reduce the internal pressure of the flask until the target vacuum level is reached, which is about 0.05 to 0.08 MPa, and the boiling point of the liquid is lowered to 40 to 60°C.

[0078] The water bath temperature of the rotary evaporator flask is controlled at 50-70℃, and the flask is rotated or stirred at 400-1100 rpm to accelerate the uniform evaporation of the enzyme stock solution and prevent local overheating and coking. The specific gravity is measured with a hydrometer to determine the concentration endpoint, and the solution is concentrated to a viscous semi-solid state with a solid content of 40-50%.

[0079] L3. Drying and pulverizing: Mix maltodextrin and concentrated enzyme stock solution in a 1:1 mass ratio and stir for 10 min. Add mannitol at a concentration of 1-5% as a freeze-drying protectant. Dispense the concentrated enzyme stock solution evenly into freeze-drying trays, controlling the thickness to ≤1 cm. Place the sample in ultra-low temperature liquid nitrogen at -40 to -80℃ for pre-freezing treatment for 2-4 h to ensure that the sample is completely frozen into a solid state.

[0080] Start the freeze dryer and reduce the vacuum to 10-50 Pa. Slowly raise the shelf temperature to -20-0°C and maintain the cold trap temperature ≤-50°C for 12-48 hours until more than 90% of the free water sublimates. Then gradually raise the shelf temperature to 20-30°C to remove bound water and maintain the vacuum at ≤10 Pa for 4-12 hours. When the sample temperature and shelf temperature are close to the same, turn off the vacuum pump and wait for the pressure to stabilize to complete the drying process.

[0081] Turn off the vacuum pump, fill the freeze-drying chamber with nitrogen, and quickly remove the freeze-dried enzyme powder. Gently crush the freeze-dried blocky material with a sterile pulverizer, sieve it through an 80-100 mesh sieve, and then seal it in a light-proof and moisture-proof container for freezing and storage at -20°C.

[0082] The beneficial effects of this invention are: the Pu-erh tea enzyme powder and its preparation method, by using raw Pu-erh tea leaves, sugar source, EM bacteria powder, and citrus peel particles and lemon peel particles as raw materials, can enhance flavor and enzyme activity to achieve multi-stage synergistic fermentation. The natural fructose and cellulose in the peel promote the proliferation of microorganisms, increase enzyme activity and organic acid production, thereby effectively improving fermentation efficiency.

[0083] By combining the entire fermentation cycle and based on the activity of microorganisms at different stages, exhaust and pH monitoring and control can be implemented to avoid problems such as fermentation runaway or contamination by miscellaneous microorganisms.

[0084] Through multiple purification steps including high-pressure sterilized gauze filtration, pasteurization, and centrifugal layered plate and frame filtration, the purity of the original solution can be effectively guaranteed. Furthermore, the low-temperature concentration and freeze-drying processes effectively improve the survival rate of active ingredients such as enzymes, probiotics, and polyphenols in the enzyme powder.

[0085] 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 Pu-erh tea enzyme powder, characterized in that, The raw materials for enzyme preparation consist of the following components in the indicated weight proportions: 100 parts raw Pu-erh tea leaves, 100-150 parts sugar source, 1-2 parts fermentation starter, 450-550 parts purified water, and 15-25 parts auxiliary materials.

2. A method for preparing Pu-erh tea enzyme powder, characterized in that, Includes the following steps: S1. Tea pretreatment: Soak the tea leaves in warm water at 35~45℃ for 4~6 minutes, and wash them one to three times to remove dust and impurities. Sterilize them in a microwave drying and sterilizing machine for a certain period of time, and then grind them in a pulverizer to obtain Pu'er tea powder. Sieve the powder through an 80-mesh sieve for later use. S2. Preparation of fermentation liquid: Select a quantitative sugar source, add it to the fermentation tank, add the proportion of pure water and stir to dissolve it completely. Then add the proportion of Pu'er tea powder and auxiliary materials and stir for 2-4 minutes. Add an appropriate amount of fermentation bacteria to the obtained mixture, seal and store it. Place the fermentation tank in a room temperature and light-proof environment for fermentation reaction. S3. Fermentation liquid filtration: The fermentation liquid residue is filtered through sterilized gauze cooked in a high-pressure sterilizer to obtain Pu'er tea enzyme stock solution. The enzyme stock solution is then treated with pasteurization to inactivate miscellaneous bacteria and concentrated under reduced pressure to a soluble semi-solid structure. S4. Drying and pulverizing: After adding maltodextrin in proportion and stirring evenly, enzyme powder is prepared by freeze drying.

3. The method for preparing Pu-erh tea enzyme powder according to claim 2, characterized in that, The specific steps of the pretreatment of raw Pu'er tea leaves in step S1 include: 1) Select a clean measuring cup and put in an appropriate amount of raw tea leaves. Add water slowly along the cup wall at a tea-to-water ratio of 1:50 to fully soak the tea leaves. Use a glass rod to slowly stir the soaking water for 1-2 minutes to ensure that the tea leaves fully unfurl. 2) Let it stand and continue to soak for 3-4 minutes. Tilt the cup wall and slowly pour out the turbid soaking liquid. Depending on the turbidity of the soaking liquid, wash the tea leaves one to three times. Take out the tea leaves and spread them flat on a dry and clean filter gauze. Place them in a ventilated and cool place for 1-1.5 hours to drain the water. 3) Spread the damp tea leaves evenly in a ceramic ware and put it into a microwave dryer. First, set the low power mode to preheat the ceramic ware for 1-2 minutes, then turn on the medium-high power mode to sterilize and dry for 3-4 minutes. On the high power mode, stir-fry and turn the tea leaves over once every 30 seconds. 4) Use a tea needle to crush Pu'er tea leaves into 1-2cm pieces, then put them into a pulverizer for primary crushing and fine crushing. During the primary crushing process, set the crushing temperature to ≤45℃, crush for 10 seconds each time and cool for 1 minute in between, sieve through a 40-mesh sieve, and re-crush any unqualified particles. 5) During fine grinding, grind for 2 minutes each time and cool for 1 minute at intervals. Check the fineness of the grinding. After passing through an 80-mesh sieve, discharge the material and seal it with nitrogen for later use.

4. The method for preparing Pu-erh tea enzyme powder according to claim 2, characterized in that, In step S2, the sugar source is selected from brown sugar, black sugar, and honey. The auxiliary material consists of 45% citrus peel particles and 55% lemon peel particles in proportion. The fermentation strain is EM powder.

5. The Pu-erh tea enzyme powder and its preparation method according to claim 2, characterized in that, The specific steps for preparing the fermentation broth include: 1) Add the measured sugar source and purified water to the fermentation tank at a ratio of 1:(4.5~5.5), and stir at a speed of 200~650rpm for 10min to ensure that the sugar source is fully dissolved to obtain a syrup solution; 2) Add Pu-erh tea powder and auxiliary materials to the syrup solution at a ratio of (4~5):1, and continue to stir at a speed of 500~1100rpm for 2~4 minutes. After mixing thoroughly, add the fermentation starter, place it in a room temperature dark environment and seal it for reaction, and control the fermentation temperature in the tank to 25~30℃. 3) Set the total fermentation time to 7-10 days. During the first 1-3 days of the reaction, the yeast is more active and produces CO2, accompanied by the generation of bubbles. At this time, the pH value of the fermentation liquid is ≤4.

0. For the first three days, it is necessary to release CO2 by venting once a day. 4) During the 4th to 7th day of the reaction, the lactic acid bacteria are more active and produce organic acids and enzymes. At this time, the pH value of the fermentation broth is 3.8 to 4.

2. 5) During the 8-10 day reaction, the pH value of the fermentation liquid is ≤4.0 and no bubbles are produced. Accompanied by the volatilization of wine aroma or fruit acid aroma, the fermentation liquid is brownish-brown.

6. The method for preparing Pu-erh tea enzyme powder according to claim 1, characterized in that, The specific steps for filtering the fermentation liquid include: 1) Set the cooking temperature of the high-pressure sterilizer to 121.3℃ and the pressure to 103.4kPa. Cook the sterilized gauze for 20~30 minutes to ensure thorough sterilization. After sterilization, filter out the fermentation liquid residue with the sterilized gauze to obtain the enzyme stock solution. 2) The liquid and tiny suspended particles in the enzyme stock solution are separated by centrifugation in a centrifuge, and the separated solid-liquid mixture is then separated by a plate and frame filter press. 3) Continue to pass the enzyme stock solution into the pasteurization device and heat it at a temperature of 68~75℃ for 0.5~1h. Then, quickly cool the sterilized enzyme stock solution to 4~5℃ and keep it at that temperature for 15~25min. 4) Pass the sterilized fermentation broth into the rotary evaporator flask, start the vacuum pump and gradually reduce the internal pressure of the flask until the target vacuum degree is reached, which is about 0.05~0.08MPa, and lower the boiling point of the liquid to 40~60℃. 5) Control the water bath temperature of the rotary evaporator flask at 50~70℃ and rotate or stir at 400~1100rpm to accelerate the uniform evaporation of the enzyme stock solution and prevent local overheating and coking. Use a hydrometer to measure the specific gravity to determine the concentration endpoint and concentrate to a viscous semi-solid state with a solid content of 40~50%.

7. The method for preparing Pu-erh tea enzyme powder according to claim 1, characterized in that, The specific steps of the drying and powdering process include: 1) Mix maltodextrin and concentrated enzyme stock solution in a 1:1 mass ratio and stir for 10 minutes. Add mannitol at a concentration of 1-5% as a freeze-drying protectant. 2) Dispense the concentrated enzyme stock solution evenly into the freeze-drying tray, controlling the thickness to ≤1cm. Place the sample in ultra-low temperature liquid nitrogen at -40~-80℃ for pre-freezing treatment for 2~4h to form fine ice crystals and ensure that the sample is completely frozen into a solid state. 3) Start the freeze dryer to reduce the vacuum to 10~50Pa, and slowly raise the shelf temperature to -20~0℃. Close the valve between the sample chamber and the cold trap, and keep the cold trap temperature ≤-50℃ for 12~48h to capture sublimated water vapor until more than 90% of the free water sublimates. 4) Gradually increase the shelf temperature to 20~30℃, remove bound water and maintain a vacuum of ≤10Pa for 4~12h. When the sample temperature and shelf temperature are close to the same, turn off the vacuum pump and wait for the pressure to stabilize to complete the drying. 5) Turn off the vacuum pump, fill the freeze-drying chamber with nitrogen and quickly remove the freeze-dried enzyme powder. Gently crush the freeze-dried block with a sterile pulverizer, sieve it through an 80-100 mesh sieve, and then seal it in a light-proof and moisture-proof container for freezing storage at -20°C.

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